Q45t fuel problem

[isaac1]

before i begin i want to say i have spent 2days looking through threads about my problem! ok here we go, my 94 q45t was low in gas one day an as im pumping gas into the car its starts skipping an missing, then 30 mins later driving home it loss power an cut off. after a couple of hours it starts but still sputtering an missing an as i drive down the road its now backfiring in small bursts. took the car to my nissan dealership an had a diagnostics test done an they said my no.1 an no. 7 injectors are stopped up, ok called infiniti of scottsdale an the new injectors are on the way but, it loses power when i make right turns an it struggles to catch up i had to pat the acclerator just to build speed an while doing this is when the small backfire bursts are present. (please help)!

[goody90q45]

Is the check engine light (CEL) on?

[Infinitiguy19]

Check the MAF sensor: http://www.q45.org/maf.html, AAC/IACV Valve (Back of the plenum and you will need a spare gasket), Fuel pressure (With an inline gauge) and if the fuel pump sounds like a hive of bee's (Buzzing) then replace or re-solder the Fuel Pump Control Unit. I almost typed Fuel Pimp Control Unit .

And find a good dealer with a Senior Tech who knows what he is doing (Was factory trained on the Q and works on them from time to time).

[isaac1]

the cel is not on just when i take off from a stand still it picks up speed very slowly with a few bucks an jerks an then boom a burst of speed comes out of nowhere or it will continue to creep slowly with small backfire bursts

[goody90q45]

the cel is not on just when i take off from a stand still it picks up speed very slowly......

Does your 94Q have 120k-140k miles?

If the CEL is not on chances are pretty good it's a fuel delivery problem- a dying fuel pump or fuel pump control unit (FPCU). With the trunk open can you hear the fuel pump (a swarm of bees) or is it quiet? Has it been noisy for a while?

A couple of easy tests will help. Tee in past the fuel filter with a pressure gauge to check fuel pressure. It should be 34-40 psi give or take. An simple test of FPCU function is to bypass it by running the fuel pump to ground. Reach in through the trunk, unplug the FPCU connector (passenger side behind the rear deck tray), and run a jumper from the pin shown in the pic to ground (the frame behind the fuel tank). If it cures the problem the FPCU has gone bad. Let us know what you find.

From trolling the other NICO forums I'm seeing that a lot of cars are having fuel pump issues now that the weather is warming up. Not just the Q45 but many other Nissan and Infiniti models.

[bigtime]

I have some of the same issues. This is some good info. I will check my pump and FPCU today.

[NYCQDude]

f the CEL is not on chances are pretty good it's a fuel delivery problem- a dying fuel pump or fuel pump control unit (FPCU). With the trunk open can you hear the fuel pump (a swarm of bees) or is it quiet? Has it been noisy for a while?

I agree it sounds like a fuel delivery problem but more than just two injectors, like the fuel pump. There is also a fuel filter inline from the gas tank under the passenger side of the chassis which is easily overlooked and they go bad sometimes and cut fuel delivery and can leak pretty severely too I might add...

Good luck!

[Infinitiguy19]

There is also a fuel filter inline from the gas tank under the passenger side of the chassis which is easily overlooked and they go bad sometimes and cut fuel delivery and can leak pretty severely too I might add...

Good luck!

Are you assuming that he has a FGY33 (1997-2001 Q45)?

You are somewhat correct in that the fuel filter is on the passenger side (Right) mounted on the shock tower. Here is my half a** video on how to replace it: http://www.youtube.com/watch?v=6RLyvARijg0

[NYCQDude]

Are you assuming that he has a FGY33 (1997-2001 Q45)?

No, actually I saw that he had a 94, but I thought the fuel filter placement may have been a standard application for more than just the 97-01. Yet even if it is applicable to only 97-01 there is a fuel filter for sure on a 94 and sometimes they get clogged or just plain shot. Not a bad first check to see if the problem is a simple cheap one before going on to the next step, just trying to help trouble shoot a bit. A fuel filter is the first thing I check (on bikes and cars) if there is a delivery problem.

Thanks for posting the vid, no doubt many will find it helpful..

[isaac1]

ok replaced the two bad injectors 1& 7 replaced the fuel filter, new plugs (ngk platinum), started the car to see what i have now before i put the fuel pump in an the misfire an idle tremor has gone car purrs like a kitten at idle to the car out for a test run still building speed slowly so im going to install the fuel pump tomorrow an monday have someone check my cataylic conveters because i think thats the culprit will let u guys know tuesday about the results. another thing ive searched and search for posts on pressure washing this engine, is it safe to do or not?

[Infinitiguy19]

Why didn't you use OEM plugs?

When you say purrs like a kitten do you mean you can't hear the car running with the hood closed and feel the car running with no radio, HVAC (AC/Heat) on? is it still smooth with your hand on the plenum?

1994-1996 Q45's do have slightly inferior catalytic converters as compared to 1990-1993 Q45's (To put it nicely). But but you better off holding off on the catalytic converter check.

If you cover all the engine electrical components and use distilled water it may be safe. But just spend the extra time and do it by hand, and then wax the underside of the hood.

[isaac1]

ok guys the fuel pump was the problem an now the car runs better than ever before, an yes the car runs very smooth u cant even hear it running, no tremble at idle nice acceleration good fuel consumption, etc. thanks guys for all your help. one more question im getting ready to change the oil tomorrow with mobil 1 is it safe to add a little lucas oil stabilizer also because my friend has a hummer an he said he uses it at every oil change? i just want to be safe.

[Infinitiguy19]

I can say I used the Lucas Power steering leak fix product way back when I had a 1991 Q45 and it didn't fix it. Now to be fair I am not sure how big the leak was.

The Lucas transmission stuff is used when the transmission is on its last leg to get you home. It swells up the seals then they explode after a while hence its use.

I would use BG MOA (Motor Oil Additive ) or the Lubro-Moly brand version of it.