The Why Won't My Fuel Pump Prime (work) thread - non NATS edition
 

Ok I've been having hell getting my fuel pump to prime under initial key turn.

So far things I have replaced/check are:

Engine Harness Grounds (two screws going into the LIM near the injectors on the VQ30DE)
Main Harness Grounds (Behind the radio)
Fuel Pump Relay (Driver side lh kick panel, behind your ABS actuator if the vehicle is ABS equipped)
Fuses # 17 and #32 (Interior fuse panel, 17 - Eng Cont, 32 - Fuel Pump)
Under Hood Fuses for the ECCS 1 & 2
Swapped ECU's

I have yet to whip out the voltmeter and start testing the signals to determine if I have a bad fuel pump or not, which is what things are pointing towards.

But can anyone else think of any reason why the ECU would not fire up the fuel pump on initial key turn to "ON"??

When things were working initial prime would be like 25-30 psi and while cranking it would rise 40+, I've since removed my FPR and just went on based the pulsing in the lines (thanks FSM!) but during my no start or turn over for a second or two then die syndrome I have not been feeling or hearing the fuel pump.

BTW my fuel pump is from a z33 w/ >30k miles on it.

FYI, these problems occured immediately after my DEK swap.

If you are getting voltage to the pump (wires probed at the pump) then you know it's probably the pump even it is considered new. No signal then I would check the wires at the relay and work forward.

So you swapped the whole motor in or just did an 00vi

But but but but but I don't wanna :sadpace:

REALLY?? :rolleyes:

You don't even know if this is an issue? :confused: Yet you made a thread?

PS, this problem is intermittent.

The one second prime might be difficult to see with a DVM. Consider an analog meter.
Have you put a fuel pressure gauge on the fuel rail to verify pressures?

Doesn't the ECU have this failsafe mode that prevents the fuel pump from running forever when the engine is not turning over? Like the ECU sees the crank sensor is not seeing movement and therfore ECU kills feul pump?

Could you ECU be overzealous somehow?

Yes/No

I wouldn't call it a fail safe, but from my half @55 2am reading of the fsm it seems that the ECU just fires the pump for a second or two every time it's powered, then it turns off until it receives signal from the CPS then it bumps up pressure again.

I'm going to change the CPS sensor AGAINNNN even though the car runs fine from time to time.

https://i50.tinypic.com/qq7q6e.jpg

Interesting, maybe I should swap out sensors again for the :lol:'z

I'm also going to do the fuel pump control module.

But I still think this is something quite simple that I'm overlooking...

Before you start swapping things, put meters on the issue.
Fuel pressure
Voltage

I just realized you removed your FPR. Why? Maybe you should put back a new one. Could have thrown the system out of whack.

It's pointless to do fuel pressure, I know what's going on and how things should be going based on a few interior cabin sounds, or just by pinching the lines on the fuel tank (long arms :D ).

Voltage was next until read below....

My adjustable FPR I was using to diagnose these things.

I already replaced the white car's original rails, FPR and Injectors w/ new injectors rails and a newer (to the white car) FPR same results because they aren't even getting any fuel :/

I've narrowed it down to a problem between the ECM and Fuel Pump or Fuel Pump Relay and Fuel Pump (I used a 95 ECU during the testing process w/o having the Fuel Pump Drop Resitor and Control Module plugged in, slightly better but same results, it'd crank over and try to run for about 3 seconds then die out).

https://i48.tinypic.com/2thq8.jpg

Also food for thought, 95's and 99's do NOT use a fuel pump control module or fuel pump drop resistors.

But cool story tonight....

I jumped the fuel pump and car runs, so then I just put everything back to normal and the car runs now too :confused:

So somehow jumping the fuel pump fixed the problem.... :gotme:

I have about the same problem. My car does not start and I have replaced....

crank sensor
fuel pump
fuel relay or so I think it was

I have verified no pressure by removing the line above the fuel filter.

Did you come to another resolution to this issue?

Thanks, Kyle

Talk a handy dandy multimeter and check a few things out.

Check to see if the pump is getting 12v.

If not you may have a wiring problem.

If the pump is getting 12v for that short burst of a few seconds then your pump took a dump, or you may still even have a short somewhere inside of the tank.

The whole point is to figure out where your problems are, it's very easy to figure out once you get something to test voltage.

If you don't have a multimeter, take two long pieces of wire to a spare car battery and jump the fuel pump directly. Use the FSM to figure out which pins you need to touch.

You should get a nice whirr goin as soon as you touch the right terminals. If that's the case then you most likely have an electical issue... Fuel Pump Regulator (On some years of Maximas), Fuel Pump Relay, etc. etc.

So last night I did bust out the DVOM and we know for sure the pump isnt getting any power at all. The relays are getting power and so it seems the ignition switch is as well. Since the car couldnt start I couldnt test the Fuel Pump Control Module correctly, or that resistor with it in the trunk. Based off of that I had come to the conclusion it is a wiring or ECU issue.....

THoughts?!

Im about to call the auto electrician. UGH!

Kyle

From what you diagnosed it looks like its the relay. Did you test both sides of the relay? It may be getting power but not turning on power for the fuel pump.

Well I thought that and so I test them and replaced them with a good relay. No go- STILL. They both got power, but still no power to the pump. The fuel level sensor has power though. What about crank pos sensor or temp sensor?

Thanks for the help!
Kyle

Answer
 

Finally broke down and took it to my auto electrician. HE said he thought the car might have been sitting for awhile. The security fuse looked to be nasty from his description so he cleaned it up and WHALA it runs again!!!! Moral of the story is to check any and all fuses even if you think they are unrelated. This explains the no fuel and no spark!!!!

He is one good mechanic who has a good understanding of modern day electronics and cars. Stick with him:thumbsup:

soooooo, :D

I am having the same exact problem as before, I guess since I didn't fix anything the car is liable to do it again, amirite??

Rechecked all of the obvious stuff, and it all works still (Fuses, modules, etc)

I am going to go further back and investigate, maybe the ECU isn't getting power afterall.

BTW I have two ecu's I keep swapping same results each time, and I know both of em can't be bad.

Are you using a 4th gen computer with a 5th gen motor, and doesnt the 5th gen motor have a different fuel system design, as in the 4th gen returns unusued fuel to the tank but the 5th gen doesn't? And, if that's the case, could it be that the 4th gen computer doesn't understand the different fuel pressure readings its getting because of the different design? :gotme:

Thanks for the try, but it doesn't matter at all.

I could have a 9th gen motor, doesn't matter, the fuel pump should ALWAYS kick on when the power switch is turned to on (fooorrr the most part)

I am going to figure out why the fuel pump relay isn't clicking at all, seems that is the source of my problem (yes the relay has been checked and it's good).











For future reference though, the car is now hybrid 3.5 swap (3.5L engine w/ 3.0 timing), using the typical fuel setup as used by most of the org's 3.5 swaps. I've had the same exact problem when the car was DEK swapped using the VQ30DE fuel rails and the problem randomly decided to disappear

Suddenly forget to ground just one wire and everybody just loses their minds :mrgone:

I have the same problem with my dek swapped 96, worked fine one day an went to crap the next. If I push start it, it'll run for days. Ima use this thread an diagnose my problem too. Hopefully its an easy fix.

What ground wire did you forget? I wanna check the same on mine, maybe it is my problem as well

Literally, ONE of the ground wires from the engine harness to timing case/lower intake manifold had a crappy heatshrink on it and it decided that running open intake manifold was too much and it came apart.

Yes, I test my motors by running them open intake manifold, problem :D ?

They run so much better with ALOT of air haha. Ima double check all my connections an grounds an see if maybe that's my problem. Was starting fine everyday while I was trying to diagnose trans issues after swap. Then one day she started starting slow an eventually not at all. Frustrating lol. Just need it fixed