Fuel Pump Replacement

Post by **SurfinGator** » Fri Sep 24, 2004 6:22 am

Installed a new pump from Scottsdale a couple of weeks back. Ran sweet, no problems. The old pump didn't appear to draw any excessive current, the Fuel Pump Controller looked clean. I replaced the fuel filter as well.

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.

Post by **SurfinGator** » Fri Sep 24, 2004 8:11 am

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 ...

Post by **911/Q45** » Fri Sep 24, 2004 8:14 am

Dismount the ECU from the passenger footwell and reconnect it. A little red light is visible that will blink short and long flashes to indicate your code. The codes are in the FSM.

Post by **maxnix** » Fri Sep 24, 2004 4:16 pm

Might want to try some ISO-Heet to see if you have any water contamination.

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

Post by **SurfinGator** » Wed Sep 29, 2004 6:52 pm

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.

Post by **SurfinGator** » Mon Oct 04, 2004 5:13 am

new/used FPM worked great for 200 miles or so ... then same problem.

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.

Post by **Q45tech** » Mon Oct 04, 2004 8:08 am

Without the ability to go too high mode, acceleration will over run the pumps ability to keep up.

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].

Post by **SurfinGator** » Mon Oct 04, 2004 8:38 am

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.

Post by **SurfinGator** » Wed Oct 06, 2004 7:28 am

grounding the pump stopped working last night. I posted this on Infinity General, though I might post it here as well.

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 ....

Post by **peety** » Sat Oct 23, 2004 9:16 pm

i recently changed out my fuel pump for a used one. which later on someone told never ever do that again. now here is my scenario. i was burger king drive through when all of a sudden the car falls dead. so i try to crank it and nothing but up and down idling until it falls dead once again. so i push my Q out of line and i try to crank it once more. i didnt hear that hum of the fuel pump. so i figured it was the fuel pump. so the next day after having it pulled to the house i go to a salvage yard to see if they had a fuel pump. they did and it looked brand spanking new. so i went ahead on and changed it. i actually pulled it from the trunk and not the rear deck (it is not recommended to do it this way again). this is also my first time working on this car. now when i changed it i was all ready to hear that humming of the fuel pump. i turned the key and nothing happened. my head hanging low. so now i have to go to the owners manual (novel) for a list of what could be wrong with it. well i checked the relay (in the trunk)' the fuel control unit and the fuse under the steerin wheel. everything was in tact. as a matter of fact i went an auto parts store to get another relay switch for the pump. i took the car into the shop. because i couldnt figure why it wasnt starting. i went back in couple of days to pick it up and he showed me what was wrong with my car. somehow it lost a ground somewhere or has a short in the wires. i still have my old pump, should ikeep it and put it back in. oh yeah i also now smell strong fuel vapors. is somethin loose in my tank

Post by **DAEDALUS** » Sat Oct 23, 2004 9:36 pm

Depends on how long you plan to keep the car. If more than a year or two I'd go ahead and spring for a new factory pump. Give the fuel smell a few weeks, the shop may have opened up the system without properly de-pressurizing it first.

Post by **Q45tech** » Sun Oct 24, 2004 3:25 am

Don't assume that just resoldering the weak link in FPCU is a universal fix, as members have seen , then the next current abused part just fails.

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.

Post by **maxnix** » Sun Oct 24, 2004 6:27 am

DAEDALUS wrote:Give the fuel smell a few weeks, the shop may have opened up the system without properly de-pressurizing it first.

As a newbie note, the return line will flow gas when it is disconnected from the pump, so have a gallon bucket into which it can drain and some old terry cloth towels you don't want to use except for automotive purposes.

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.

Post by **maxnix** » Sun Oct 24, 2004 6:30 am

Uhhh....how do I delete?

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

Post by **azsvb** » Sat Jan 29, 2005 7:56 pm

Hello.. thanks to all of you folks who has written about changing fuel pumps. I did mine today (1995 Q45.. bought it used and the fuel pump was humming bad).. now i dont hear the hum and it run ok thus far!...will be driving to vegas from phx.. sunday nite.. fuel pump 338.23 from scottsdale infiniti..O ring at 8 bucks!

Post by **oxs1** » Wed Feb 02, 2005 3:54 pm

Hey tang can you send me the pics of the fuel pump installation at [email protected]

Post by **pprovo1** » Mon Mar 07, 2005 8:59 am

Hello tangalora- can I get some of those pictures of your fuel pump replacement too? [email protected]

Post by **Q45tech** » Tue Mar 08, 2005 3:32 am

I will again post my thoughts on a wonderful device:

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 openPosition 3 the pump negative wire goes to a good ground.

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

Post by **maxnix** » Tue Mar 08, 2005 9:23 pm

Thanks for the reminder. A write-up by the first installer would be helpful for us of the electrically illiterate. Seems like the switch would need a guard in the trunk so as not to be accidently triggered at a bad moment by loose items.
Modified by maxnix at 8:01 AM 3/9/2005

YouTube · Post by **Jesda** » Wed Mar 09, 2005 5:53 am

Thats a pretty darn good idea!

<- Seriously considers a drive to Radio Shack today.

Post by **kjselv** » Sat Jul 30, 2005 4:12 am

Just Curious if anyone has a book on the 94 q45 they can send me copy's of by e-mail also if anyone has fuel pump replacement pictures and perhaps pic's of a bad control unit and relay switch?

Thanks

Post by **teamkad** » Sat May 05, 2007 7:38 pm

Your instruction could have not come at a better time. My fuel pump went out on my 94q45, your pictures would really help me. can you please send them to [email protected]

Thank you:

Post by **maxnix** » Sat May 05, 2007 8:14 pm

kjselv wrote:Just Curious if anyone has a book on the 94 q45 they can send me copy's of by e-mail also if anyone has fuel pump replacement pictures and perhaps pic's of a bad control unit and relay switch?

Thanks

Too large to email.

http://www.phatg20.net

Post by **maxnix** » Fri Apr 25, 2008 2:45 pm

Or even better

http://www.nicoclub.com/FSM/Q45/

Fuel Pump Replacement

hesitating after new pump install ....

Re: hesitating after new pump install .... (SurfinGator)

Re: hesitating after new pump install .... (SurfinGator)

Re: (911/Q45)

Re: (SurfinGator)

Re: (SurfinGator)

Re: (Q45tech)

Re: (SurfinGator)

Re: (Touchdown038)

Re: (DAEDALUS)

Newbie cautions (DAEDALUS)

Re: Newbie cautions (maxnix)

Re: (tangalora)

Re: (pprovo1)

Re: (Q45tech)

Re: hesitating after new pump install .... (SurfinGator)

Re: (tangalora)

Re: hesitating after new pump install .... (kjselv)

Re: hesitating after new pump install .... (maxnix)

Nissan Forums

Infiniti Forums

Datsun Forums

Technical Forums

Classifieds / Marketplace

Nissan Motorsports

General Forums