so i could see 37-47 minutes

(all approximated times)

Heath

Basically, it puts in one post all the things I've learned from all of you here and at the yahoo message boards.

I'll post it next, but, I understand you may yank it due to the length.

ALora

The 4.5 liter 8-cylinder engine cranked wonderfully, but would not catch.
It wasn't the starter motor nor the battery (as it rotated perfectly).
As always, it had to be either gas, air, spark, compression, or timing.

Following is an idealized path others can follow to debug & repair.

Note: My actual debug & repair path took three weeks and much trial &
error; which is exactly why I wrote this howto for others to follow.

Note: Re-assembly, in all cases, is the reverse of the dis-assembly
procedures described below.

Note: This dozen-step diagnostic, removal, & replacement procedure is
accompanied every step of the way with digital photos illustrating
every described action.
----------------------------------------------------------------------------
1. I ran a quick visual/audible gas, air, spark, compression & timing check:

GAS: The gas tank was completely full (filled the night before).
The 15 amp fuel pump fuse was intact (replaced it anyway).
I could NOT hear the fuel pump humming (at any time).
AIR: The air intake & air filter were not clogged (left it open).
SPARK: I did not know how to run a quick test for spark.
COMPRESSION: The engine did sound like cylinder wash (no compression?).
TIMING: The camshaft rotated (looking in the oil-filler hole).
----------------------------------------------------------------------------
2. I soon realized no gasoline was being pumped INTO the fuel filter:

- I removed the 15 amp fuel pump fuse (by the driver-side right kneecap);
- I cranked the engine in order to release any residual fuel pressure;
- I removed the two 10mm bolts holding the fuel filter clamp to the body;
- I removed the two #2 phillips screws holding the fuel filter hoses on;
- I replaced the 15 amp fuel pump fuse and cranked the engine again.
- No gasoline spurted out of the open fuel line hose.

Note: One clue was that, after an overnight sitting, with the fuel filter
and activated carbon fuel cannister still on the car, the engine
started for a split second. This happened for two mornings.
I suspect this momentary ignition was due to the burning of
fuel fumes collecting in the fuel system over long periods of time.

Note: I blew through my fuel filter and there was almost no resistance;
so, despite the fact almost everyone says that a clogged fuel filter
can cause the fuel pump to overwork and therefore heat up and
therefore melt the solder connections on the fuel pump control unit,
I suspect a clogged fuel filter was not my problem.
----------------------------------------------------------------------------
3. I studied the 1990 Q45 fuel system electrical & hydraulic circuits:

ELECTRICAL:
- Battery voltage goes to the fuel pump relay ...
- to the fuel pump (in the gas tank) ...
- to the fuel pump control unit (under the rear sundeck platform) ...
- which provides three resistive paths (fuel pump speeds) to ground ...
- based on input from the engine control unit (passenger side dash).

HYDRAULIC:
- Fuel is pumped out of the fuel tank ...
- to the inlet of the fuel filter ...
- to the fuel line & fuel plenum ...
- to each of the 8 fuel injectors (which open at the same time) ...
- with pressure regulated by the 43 psi fuel pressure regulator ...
- which sends unspent fuel back to the fuel tank for recovery ...
- and which allows fuel vapors to be trapped in the carbon cannister.

INTERNET:
- Factory shop manual & technical service bulletins & recall notices:
http://www.nissan-techinfo.com/infiniti
- Infiniti mechanics and afficianados on line to help you:
http://nissaninfiniticlub.net
http://groups.yahoo.com/group/infinitiownersclub).
- Basic USENET newsgroups (not much help compared to the above):
http://groups.google.com/group...i.q45
http://groups.google.com/group...issan
http://groups.google.com/group....tech
- Parts:
http://www.infinitipartsusa.com
Fuel Pump (includes the fuel pump 0-ring): $234.99 + sh & tax
Fuel Pump Control Unit: $xxx.99 + sh & tax
Fuel Pump Relay: : $xxx.99 + sh & tax
Fuel Filter: : $xxx.99 + sh & tax

LOCATIONS:
- The fuel tank is located in the center of the trunk room (between
the rear seat and the trunk).
- The fuel pump & fuel pump resistive gage & filter sock is located in
the top of the fuel tank.
- The fuel pump control unit is located on the underside of the rear
metal sundeck (near the rear passenger side speaker housing).
- The fuel pump relay (lime green) is located next to the antenna and
fuel tank gasoline inlet in the area between the rear passenger side
fender and the rear passenger side trunk fiberboard lining.
- The fuel filter is located on the passenger side of the engine
compartment bolted to the inside of the passenger side fender wall.

ACCESS:
- Access the fuel pump, fuel pump relay, fuel pump control unit, & the
related fuel system harnesses for test from the rear trunk area.
- Access the fuel pump for removal & replacement either by removing the
rear seat & sundeck & storage binnacle or by dropping the fuel tank
(rear seat removal access is preferred over tank removal by most).

TERMINOLOGY:
- The harness connector (white, female) to the fuel pump control unit
is called the fuel pump control unit harness connector.
- The harness connector (green) to the fuel pump relay is called the
fuel pump relay harness connector.
- The harness connector (blue, female) to the fuel pump is called the
fuel pump harness connector.
Likewise:
- The connector (white, male) on the fuel pump control unit
is called the fuel pump control unit connector.
- The connector (green) on the fuel pump relay is called the
fuel pump relay.
- The connector (blue, male) to the fuel pump is called the fuel pump
connector.

TOOLS:
- Two #2 phillips screwdrivers (one six inch, & one two inch stubby).
- Two box wrenches (one 8 mm box & one 10mm) for bracket bolts.
- One 19 mm open-end wrench (for the gas tank fuel line lock nuts).
- One 16 AWG wire, about a foot long, with an alligator clip on each end.
- One volt-ohm-amp-meter (Fluke 77 or equivalent) with alligator clips.
- One needle-nose pliar or standard pliars (for spring-closed hose clamps).
- One paring knife (or similar) for removal of sound-proofing material.
----------------------------------------------------------------------------
4. The fuel pump relay checked out OK for proper operation under load:

FROM THE TRUNK:
- I removed the trunk room fiberboard bulkhead (between the rear seat
back & the trunk) by removing the 7 black #2 phillips screw-type
butterfly anchor clips holding the fiberboard bulkhead to the steel
supports.
- I removed the trunk passenger-side bulkhead (between the trunk and
the rear fender by the radio antenna & fuel filler opening) by removing
the 5 black #2 phillips screw-type butterfly anchor clips from their
supports.
- I removed the single 10mm bolt holding the two-pronged relay bracket
which held a blue relay (courtesy lamp relay) on one prong and a
lime-green (fuel pump relay) relay on the other.
- I pulled the lime-green fuel pump relay off the bracket tang.
- I jumped 12 volts DC across pins #1 and #2 (hearing a sharp click).
- The resistance fell (from infinity) as the actuator closed (to zero).

Note: I also checked power to the fuel pump relay, continuity from the
fuel pump relay to the fuel pump relay harness, continuity from
the fuel pump relay harness to the fuel pump harness, & continuity
from the fuel pump harness to the fuel pump control unit harness
(all asp per the factory shop manual EF & EC-169); but, not
surprisingly, I'm told the fuel pump relay and these fuel electrical
system wires almost never go bad; so consider this entire step an
ancillary case of over diagnosis.
----------------------------------------------------------------------------
5. The old fuel pump passed the basic factory shop manual test:

FROM THE TRUNK:
- I disconnected the fuel pump harness connector (blue, in the trunk room).
- As per the factory shop manual (EF & EC-185), I checked the resistance
between the top-left and the top-right (tab on top, facing terminal side)
of the six male terminals on this fuel pump connector.
- My resistance was 0.9 to 1.1 ohms which was inconclusive since the
factory shop manual merely states the resistance to be 0.5 ohms but
the factory shop manual does not supply a range value.

Note: It seems this factory shop manual test is almost useless.
When I tested the new fuel pump, it too tested about the same at
0.6 to 0.8 ohms. The online Infiniti mechanics noted the resistance
test merely checks one (of many) commutators. Online mechanics say
the clearest sign of a bad pump is HUMMING.

I must admit, the new pump barely made a sound, even when jumped
directly to ground providing it full battery voltage. I didn't
realize it at the time, but, the old pump actually hummed loudly.
(There is so much soundproofing that I never heard the old fuel
pump motor hum until the rear trunk room lay bare & exposed.)
Basic recommendation: If the fuel pump has 100K miles on it; or
if the fuel pump is humming at all audibly; then replace it
(before it burns out the ground wire on the fuel pump control unit).

Note: The two most basic tests should have been (in hindsight):
- Did the 1990 Infiniti Q45 have more than 100K miles?
- Did the 1990 Infiniti Q45 fuel pump have an audible hum?
If either answer were yes, then replace the '90 Q45 fuel pump.
----------------------------------------------------------------------------
6. The old fuel pump control unit failed the basic bypass test:

FROM THE ENGINE COMPARTMENT:
- I reconnected the fuel filter (passenger side of the engine compartment).

FROM THE TRUNK:
- I reconnected the fuel pump harness connector (blue, in the trunk room).
- I removed the fuel pump control unit harness connector (white, female)
from the fuel pump control unit connector (white, male) mounted directly
on the fuel pump control unit.
- Note: Nothing else was removed at this time; the fuel system was
otherwise completely intact.
- I filed an alligator clip's teeth so that it fit into the small female
tab on the bottom left (terminal side, with the clip up) of the white
fuel pump control unit harness connector.
- I connected the other side of the alligator-clip one foot long 16 AWG
wire to a convenient ground (expecting from 7.5 amps to 15 amps based
on fusing).
- I turned the ignition to "ON" and listened for the fuel-pump humming.
- It hummed for about 10 seconds after turning the ignition to ON.
- I started the 1990 Infiniti Q45; it ran like a charm.
- The current draw was about 5.8 amps on the old humming fuel pump.
- The engine shut down approximately 2 seconds after disconnecting this
fuel pump control unit bypass jumper.

Note: I drove the car for more than a week (about 200 miles) with this
alligator clip shorting the fuel pump to ground bypassing the
three-position (slow@5.5 to 5.7 volts, medium@7.5 to 8.1 volts, &
fast@11 to 14 volts battery voltage) fuel pump control unit settings.

Note: Online mechanics estimate the old fuel pump might last a few weeks
(running full speed as it is when jumpered to ground); while a new
fuel pump may last a few months in this temporary full-power state.

Note: It is recommended the fuel tank be kept full whenever operating the
Infiniti Q45 in this state as the fuel pump is cooled by the
gasoline in the fuel tank.

Note: This is NOT the procedure in the factory shop manual (EF & EC-185).
This procedure is much simpler than that in the factory shop manual.
The procedure in the factory shop manual requires three test jigs,
of four, five, and then six wires between the white female fuel
pump control unit harness connector and the white male fuel pump
control unit connector. In most cases, this test is overkill.
----------------------------------------------------------------------------
7. Reconcile yourself to the fact you have a few hours of work to perform:

Q: Why?
A: Because of these three basic facts.

FACT 1: The first fact is that the proper removal of the fuel pump
control unit is from the rear-seat direction & not from the
(otherwise more convenient) trunk-forward direction.

FACT 2: The second fact is that experienced Infiniti Q45 mechanics
have concluded most fuel pump control unit failures are due
to the fuel pump itself beginning to fail (and thereby to
draw excessive current, which melts the weak solder joints on
the ground wire printed circuit board connection on the fuel
pump control unit).

FACT 3: Therefore, if you merely replace or re-solder the broken fuel
pump control unit, you'll eventually burn out the new or newly
repaired (and much more expensive) fuel pump control unit.

The good news is the Infiniti mechanics online have reported very few
(if any) failures of the repaired or replaced fuel pump control unit
once the fuel pump is replaced (for another 100K miles or so anyway).
----------------------------------------------------------------------------
8. Remove the rear seats, rear sundeck shelf, and rear package binnacle:

REMOVE REAR BENCH:
- Move the front seats forward as far as they will go and tilt the
front seat backs forward as far as they will go to obtain working room.
- Locate the two black clip extensions on the rear seat floor area and
pull out those two black clip extensions simultaneously pulling up on
the leading edge of the rear seat bench to lift it upward and out.
The rear seat bench removal requires no bolts to be removed.
There are only four clips in the leading edge; and two clips in the
trailing edge of the rear seat bench to take into account for removal.
- Scavenge the $1.35 (on average) in loose change under the rear bench
that the federal government suggests wreckers earn per car on wrecked
cars.

REMOVE REAR SEAT BACK:
- Pop out or pry out (with a thin flathead screwdriver) the four blue
solid butterfly anchor clips from the leading edge of the rear topside
sundeck where the sundeck overlaps with the rear seatback.
- Remove the two rear headrests by pressing the driver-side knob under
each & simultaneously lifting upward until the posts clear the seatback.
- Push down the rear seat armrest and pull back on the vertical backing
which is velcroed to the steel bulkhead behind rear seat back.
- Remove the two #2 phillips screws behind this velcroed rear armrest
compartment.
- Remove the four #2 phillips screws holding the U-brackets at the
bottom of the rear seat back.
- Pull up the rear seat back vertically, to clear three reverse-u-shaped
wire brackets from their u-shaped metal brackets in the rear bulkhead
metal wall. This should remove the seat (except for the seat belts).
- Pull out the two side rear seat shoulder belts as far as they will go
and jam a pen or other object to eliminate the return tension.
The seat belts will be less of a nuisance if you perform this task.
- Flip the rear seat back (still attached by the seat belts) upside down
so that the foam side is facing the front & the leather side is facing
the rear and the headrest portion is on the floor of the automobile.

REMOVE REAR UPPER TAIL-LIGHT & REAR SUNDECK:
- After removing the three blue solid butterfly clips on the leading
edge of the rear sundeck ...
- Pull toward the front and upward on the rear upper tail-lamp housing;
and disconnect the rear upper tail-lamp harness connector from the rear
upper tail-lamp connector. Remove the rear tail lamp housing.
- Pull up on the rear sundeck everywhere you can to unclip the 11 solid
white anchor clips (4 equally spaced in the rear, two in the middle
on each side of the package binnacle, and 5 near the front of the
sundeck shelf, three of which are closely spaced near the middle front
of the sundeck shelf and the other two nearer the outside edges).
- Collect all anchor clips in a zip-lock bag marked "rear shelf".

REMOVE REAR SUNDECK PACKAGE BINNACLE:
- With the rear upper tail-lamp & rear sundeck removed, unscrew the
seven #2 phillips screws holding down the black plastic rear sundeck
package binnacle (aka storage compartment basin).

Note: This rear sundeck storage binnacle is the key to removing the
fuel pump since the fuel pump (with the attached fuel pump float,
fuel pump housing, fuel pump level gage, etc.), can only come out
undamaged through the rectangle left by the removal of this rear
sundeck storage binnacle (aka package binnacle).

Note: Almost none of this removal procedure is explained in the factory
shop manual.
----------------------------------------------------------------------------
9. Remove fuel pump assembly from the top of the fuel tank from the trunk:

FROM THE TRUNK:
- Disconnect the blue male fuel pump connector from the blue female
fuel pump harness connector.
- If you haven't done so already, bleed pressure out of the fuel system
by cranking the engine with the fuel pump fuse (driver side dash, by
your kneecap) removed. Also remove the fuel tank inlet gas cap.
Have a large hotel towel handy because it's inevitable that fuel
will leak as you remove the fuel pump assembly from the fuel tank.
- With a 19mm open-end wrench, remove the two 19 mm tubing nuts holding
the metal fuel pump outlet and vapor lines to the top of the fuel pump
assembly. Be careful not to break the three-line plastic separator
(as I did) when bending the rigid metal fuel lines out of the way.
- With an 8mm box-wrench or a three-inch stubby #2 phillips screwdriver,
remove the six 8mm bolts holding down the fuel tank assembly cover
plate to the fuel tank.
- Gently pull up on the fuel pump assembly taking care to prevent the
six-inch black rubber O-ring from falling into the fuel tank.
- From the trunk, twisting gently as needed through the rear sundeck
shelf package binnacle opening, remove the fuel pump assembly.
- From the rear seat area, look down into the opening left by the
removal of the rear sundeck package binnacle and inspect the fuel
tank for debris (mine was as clean as a galvanized chambered whistle).
----------------------------------------------------------------------------
10. Remove the fuel pump from the fuel pump assembly:

OUT OF THE CAR:
- Pull out the two one-inch brown plastic alignment clothes-pins
in the fuel pump wing bracket.
- Remove the two #2 phillips bolts bracing the fuel pump body to the
fuel pump assembly.
- Remove the one #2 phillips bolt holding the fuel filter sock to the
metal fuel assembly (and push out the alignment tab).
- Remove the #2 phillips bolt attaching the power wire and the #2
phillips bolt attaching the ground wire to the fuel pump itself.
- Gently force the fuel pump motor black rubber wings out of their
braces in the fuel pump assembly leaving just the fuel hose attached.
- Once the fuel pump wings are outside their slots, use pliars to
open the spring hose clamp on the plastic fuel pump outlet nipple.
- Remove the (now unattached) fuel pump from the fuel pump assembly.
- Compare the old fuel pump (in size & shape) to the new pump (the
two fuel pumps should match exactly).
- The replacement follows the reverse procedure.

Note: I purchased a new fuel pump from a parts store for $312.oo while
the Infiniti dealership listed the fuel pump for $320. The
Infiniti dealership sold me the six-inch fuel pump O-ring for
$13.oo (all numbers include tax). I noticed, afterward, that
online, I could get the same pump (including the six-inch O-ring)
for $235 plus shipping & tax. Go Internet, if you have the time.
----------------------------------------------------------------------------
11. Remove the fuel pump control unit for replacement or repair:

FROM THE TRUNK:
- From the trunk, on your left side with your head facing the driver
side rear fender, with your right arm through the opening left by the
removal of the rear sundeck package binnacle, place your index finger
on the topside location of the bolt head for the two bolts holding the
fuel pump control unit bracket to the underside of the rear sundeck.
- Have a partner mark the location of the two bolt heads (the actual bolt
heads are buried under 1/8th inch thick rubberized soundproofing material)
using whiteout or other suitable marking on the black gunky material.

FROM THE REAR SEAT AREA:
- With a small paring knife, cut out the rubberized gunky black sound-
proofing material on top of the two 10mm bolt heads.
- Use a 10mm box wrench to remove the two bolts holding the clamp on
the underside of the package shelf. Note that the clamp itself forms
a U, with one portion of the bracket above and one portion below the
metal horizontal sundeck shelf.

BACK IN THE TRUNK:
- Check that the fuel pump control unit (white, female) harness connector
is disconnected from the fuel pump control unit (white, male) connector.
- Remove the fuel pump control unit (with the bracket assembly attached)
by pulling it toward the rear of the car, and downward.
----------------------------------------------------------------------------
12. Inspect, repair, or replace the fuel pump control unit:

OUT OF THE CAR:
- Remove the four #2 phillips head screws holding the top plate
(with bracket assembly) of the fuel pump control unit.
- Remove the four #2 phillips head screws holding the bottom plate
of the fuel pump control unit.
- Inspect the wiring everywhere; notice any charred or burned areas
(my ground wire on the bottom right (terminal side, tab on top) of the
white male fuel pump control unit connector was charred a bit.
- Also, there was infinite resistance between that bottom-right male
terminal and the corresponding printed circuit board connection
(marked #4 on the PCB) on the underside of the printed circuit board.
- I used a 25-watt soldering iron & a blue solder sucker to vacuum up
the solder around that #4 pin and I re-soldered that ground pin.
- I also added a two-inch patch of 16AWG copper wire, soldered to that
#4 pin and to all the connections on the printed circuit board I could
identify as being that same ground connection.
- Test with a ohm meter that the resistance for that one ground lead
is near zero; and that accidental shorts to other traces did not occur.
- Replace the now-repaired fuel pump control unit in the reverse order
of removal.

Note: Do not power-up the fuel pump control unit out of the car as the
holding bracket supplies the main ground for the fuel pump control
unit itself.

Note: The #4 terminal is the ONLY terminal on the male white fuel pump
control unit connector which is surrounded by EMPTY pins in the
white female fuel pump control unit harness connector.
----------------------------------------------------------------------------
POST MORTEM:

THINGS I LEARNED THE HARD WAY:
- Basically, I should've replace the fuel pump at 100K miles!
Apparently they all eventually go bad. I should have also listened
for the now tell-tale hum (I never even noticed it before).
- Also, once before, about six months ago, my car would not start for
about an hour; and then, all of a sudden, started. At the time, I
chalked it up to cylinder wash (loss of compression due to gasoline
washing the oil off the piston walls causing rings to temporarily not
seal); but now I realize it was probably the fuel pump control unit
#4 pin solder heated up and, when it cooled, it re-connected itself.
- It was recommended we should fill up when just about on one quarter
of a tank (or so). The (unsubstantiated) argument states that the fuel
pump heats up, causing more current draw (how?) which causes the solder
connection on the fuel pump control module ground circuit to heat up
which, if it melts, can cause the open circuit that I found in mine.
- The new six-inch fuel pump O-ring looked EXACTLY the same as the old
one (condition was imperceptably different). So much, I ended up mixing
the two accidentally, and I couldn't tell them apart. Be advised.
- The new pump made almost NO SOUND. I didn't even realize that until
I had replaced it. Even with the full-power jumper bypassing the
fuel pump control, the new fuel pump hummed vastly less than the old
fuel pump hummed.
- The current draw and resistance measurements of the old fuel pump
and the new fuel pump were almost the same; so do not rely on these
figures as a diagnosis test (listen for hum or check your odometer):
OLD FUEL PUMP: NEW FUEL PUMP:
0.9 to 1.1 ohms 0.6 to 0.8 ohms (from the blue male FP connector)
5.6 to 5.8 amps 5.8 to 6.7 amps (with the FPCU bypass to ground)
- The factory shop manual makes NO MENTION of the quick and easy test
jumpering the fuel pump control unit harness connector to ground.
Instead, the factory shop manual walks you through an apparently
unnecessary lengthy step-by-step debugging process requiring the use
of a three, four, and then a five wire jig to debug the fuel pump
control unit. Don't overdiagnose. Just use the jumper and if the
fuel pump operates, then replace BOTH the fuel pump and the fuel
pump control unit (or repair the fuel pump control unit).
- For the longest time I was confused about the various debugging
procedures in the factory shop manual. What cleared it up was the
realization of all the proper connector names! I've made a sincere
attemp in this note to use the proper names at all times.
- Many folks say you can test the deliver of fuel past the fuel filter
(in the engine compartment) by squeezing the hole while the engine
is cranking to feel for fuel pressure. I can't tell. I recommend
removal of the fuel filter. It provides proof positive.
- The factory shop manual goes into the engine control unit debugging.
It was not needed in my case so I'm glad I skipped that part.
- The hardest thing in the world was to find the locations of the
various units; and to find out how to remove some of them. In this
note, I take special care to describe both the name of the unit and
the precise location, for others to benefit.
- Most folks recommend disconnecting the battery & removing it from the
car when working on the fuel tank. I didn't do this, but you should.
----------------------------------------------------------------------------
****************************************************************************

Way to go. :)

- Rebuilt (by yours truly) KA24E, stock specs.
- Centerforce DF clutch
- Ghetto eBay air filter
- Removed AIV
- Synthetic tranny / diffy fluid
- And a whole lotta love

But, alas, I do not know how to post photos.

Is there an easy way to both post a set of (over 30) photos which will help the next person immensly & to associate those photos with steps in the howto I wrote above?

Please let me know.

Learning from you, I left the rear fiberboard bulkhead panel between the rear seats and the trunk off so I could check the heat eminating from my now resoldered & reinforced 1990 Q45 fuel pump control unit (aka fuel pump modulator).

I haven't done any raceway driving yet, but, even after 20 miles on the highway on the way to the hospital, when I put my hand on the FPCU cooling fins, I can merely tell it's slightly warm.

For sure, it's not hot by any means. I've been checking this for two weeks now, with nary a rise in temperature.

It would be nice if others posted their results after their R&R jobs so we can benefit from statistics of more than just two.

I was also wholly unfamiliar with the number and location and type of butterfly clips holding down the rear package sundeck which needed to be removed once the brake light was pulled off.

Attached is a photograph with each of the 11 butterfly clips identified (5 in front, 4 to the rear, two in the mid section).

By publishing this photograph, I'm hoping the next person who has to remove this sundeck has a heads up that we never had.

Alora Duncan

Attachment: nico_rear_sundeck_package_shelf.jpg (45376 bytes, downloaded 5995 times)

The nice thing about modern digital gauges is that the sensors are similar in voltage/resistance.......a oil pressure sender can be a fuel pressure sender [if the sensor survives the gasoline].

2 gauges in car one for pressure one for temperature and rotary switches to monitor multiple sensors.......nice clean looking diagnosis panel.

A 3rd which might read voltage for TPS, battery, other things......voltage reading can translate to current reading with shunts.

a) NICO Forums > Online Mechanic > Infiniti Online Mechanic > 1992 Q45 fuel pump modulator
http://www.nissaninfiniticlub....=3984
b) NICO Forums > Online Mechanic > Infiniti Online Mechanic > Installing Fuel Pump Control Module??
http://www.nissaninfiniticlub....36948
c) NICO Forums > Online Mechanic > Infiniti Online Mechanic > problem after changing fuel pump
[/http://www.nissaninfiniticlub.com/f...&threadid=14348
d) NICO Forums > Online Mechanic > Infiniti Online Mechanic > q45 fuel pump/control module
http://www.nissaninfiniticlub....34503
e) NICO Forums > Online Mechanic > Infiniti Online Mechanic > Fuel pump problem
http://www.nissaninfiniticlub....11900
f) NICO Forums > Online Mechanic > Infiniti Online Mechanic > feul pump control unit (sic)
http://www.nissaninfiniticlub....18148
g) NICO Forums > Online Mechanic > Infiniti Online Mechanic > Fuel Pump Replacement
http://www.nissaninfiniticlub....=6268
h) NICO Forums > Online Mechanic > Infiniti Online Mechanic > Fuel pump
http://www.nissaninfiniticlub....47728
i) NICO Forums > Online Mechanic > Infiniti Online Mechanic > q45 fuel pump controller
http://www.nissaninfiniticlub....73822
j) NICO Forums > NICO General > Infiniti General > Fuel Pump Pictures
http://www.nissaninfiniticlub....d=454
k) NICO Forums > NICO General > Infiniti General > Q45 fuel pump modulator
http://www.nissaninfiniticlub....13588

Attachment: nico_q45_fuelpump_and_fpcu.jpg (17619 bytes, downloaded 5642 times)

Thanks, Again

Adam

This week the car starting hesitating when running and stalling when stopped. Not when it first runs, but after a few minutes. Then it will go away, work great. I cleaned the MAF, a full can of Electro-clean, and verifed the wiring was in good condition ... it was like new.

I just went out and re-connected all the FPC connectors, used a small screwdriver and made sure all pins got a firm grip.

heading to AutoZone now for a can of bad gas remover and a fuel gauge ....

can someone explain where to read the error codes when my Q stalls again?

92 Q45 117K miles .... Jackson MS.

AutoZone guy said he didn't have a fuel gauge that would work with my car? ... I just looked at him ... ok ...

passed anway, jumped the FPC pin to ground and drove all over ... works great. Opening it up and soldering the connections ...

But you steam cleaned your tank, right? Else contaminants will shorten the new pumps life.

Discover the power of the button!

thanks 911! ... I will check it tomorrow. The soldering seemed to work ... I drove it round trip about 150 miles with no problem ... then this afternoon it just went into convulsions! DAMN!

I tried a bottle of water remover in the tank already ... and I had replaced the old fuel filter when I did the install ... so now I am salvage yard looking in the morning. I was going anyway for dink things .... ash try and a front badge ... but will look for a modulator there now as well.

Does anyone know what resistive values the FPM gives to the Fuel Pump? Is there a problem with using a set value of resistance to run the pump?

I don't want to drive this with the pump shorted and driving my Q with this problem is not an option.

Same problem with a cold start and priming the system.

They designed the system the way they did because they had too. No car manufacturer is going to waste an extra $150-$175 [their cost].

Any idea what the resistive values are for the different modes?

I would lock it in High mode for the brief time I drove the car, I have two cars. Don't like the idea of dead short to ground, if I could limit the current any that would be better than maxed I assume.

here is an indepth description of what has occured:

The history:

My car had no problems except the fuel pump was buzzing. I replaced it with a OEM new one, fuel filter at the same time. Three weeks later, the car would randomly sputter and want to die. At mid pump output, the pump is three stages, a one second pause would occur in the car. When I stopped, low pump output time, it would stall. Putting the car in neutral and revving the engine would stop it from stalling. Then it would go away. I could drive it for miles and no problem.

Grounding the fuel pump resolved it. After ISO-Heet in the tank, cleaning the MAF, and re-soldering the connections, it appeared to work. Next day, at it again. I replaced the FPC with a salvaged unit, worked for a few days and then at it again.

I can run the car 70-80 mph on cruise control and it works fine on the highway for 400 miles. When I slow to go through a town, you might make it without it sputtering, but even if it did it usually sputters when you first re-engage the cruise to 70-80 again. Zoom Zoom, then sput sput for two seconds ... then clean ... for another hundred miles before you have to slow down.

I am heading to the dealer this afternoon, there goes my paint job ....

There is a reason we and dealers always change the pump, FPCU, and relay out as a single operation, unless the pump is just changed for noise without intermitent symptoms.

If you have a standard model G50, while sitting in the passenger's back seat, grab the CHMBL with your right hand on the driver's side of it and rotate it back towards you. Once it is free, the power plug's safety release is easily available to your left hand.

The first three package tray retainers are available under the top of the back seat, but the rest are best released from inside the trunk with needle nose pliers.

The shoulder belt anchors anchor bolts penetrate through to the underchassis and will be dirty on the ends, so don't let them dangle against your seats.

Lastly, be sure you remember to reinstall the center package tray bin before reassembling the intierior, or you will get more practice.

For some reason, first the passenger side CHMBL bulb burned out, then when I replaced it (OEM only!), the other one did also.

If you want to clean your tank and fuel lines, you will need a lift to remove the fuel lines to get the tank out. Or be extremely trusting of jack stands. I personally don't want to die for a fuel pump, nor for a cleaned tank.

Finally, it will take hours of idling to consume all the gasoline even after the low fuel level light illuminates.

Wow a spell check button! Never another misspelled post again! Kudos to the NICO team.

A 3 position 15 amp toggle switch mounted in the rear package tray.

Position 1 the pump negative wire goes to the FPCU as normal from factory.
Postion 2 center the circuit is open
Position 3 the pump negative wire goes to a good ground.

Emergency FPCU failure bypass to get you home/shop
Secret engine immobilizer with switch off [not that many try to steal old Q]
Diagnostic aid.

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<- Seriously considers a drive to Radio Shack today.