Hello,

My car suddenly died shortly after driving and will no longer start. It cranks and wants to start, but it just wont go.

I should note that my car has been sitting in my garage with barely any gas for several months prior to driving it.

I determined that there is no fuel getting to the engine. I replaced my battery (it was old) thinking maybe there wasn't enough juice to start the fuel pump. No start. I changed the fuel pump fuse; no start. I then removed the fuel pump, connected it straight to my battery and confirmed that its working great.

I then tested the wire harness and discovered that the positive lead for the fuel pump is not reading any current. Every other wire reads a steady 11v.

I'm not sure where to go from here. I thought about a relay, but i cant seem to find anything about there being a fuel pump relay or where its at. (ref: http://www.nicoclub.com/FSM/G37/Coupe/2008/FL.pdf)

Does anyone have a IPDM diagram for a 2008 G37S Coupe? I'm thinking the relay is in there.

update: for reference, found it here: http://www.nicoclub.com/FSM/G37/Coupe/2008/PCS.pdf according to this diagram, the relay may be integrated and unremovable. will have to check it tomorrow.

Any suggestions?

Thanks.
-B

 

Look here

http://www.nicoclub.com/FSM/G37/Coupe/2008/PG.pdf

See page PG-51

Did you check the 15A fuse for the fuel pump relay with a meter?

May be a defective IPDM module?

Good luck

Telcoman

 

Thanks for the advice. I replaced the fuse, didn't check the relay though.

I spoke with a nissan engineer today, advised me that is by design. Power for the fuel pump is fully grounded at all times. Current is pulsed when you step on the accelerator (normal driving) and is controlled by the ecu. FOT sends full current to the pump. This would explain why I was not reading any current in that wire.

He recommended that I test the relay, which he confirmed is in the IPDM box. He said the relays are all the same in that box so I can probably just swap one for testing purposes.

He also advised that the fuel pump, after having run dry (no gas in tank), will take a good 30-45 seconds to prime and numerous cranks before it will actually start.

I haven't had a chance to work on my car, so i'm going to be doing this tomorrow to see where I get. He invited me to give him a call back should the relay test good.

I'll keep this thread updated as I go.

 

I think your Nissan engineer described the throttle body operation. The fuel pump is either on or off. There is no pulsing of current.

Here is a snippet from EC-519 in the factory shop manual:Infiniti G35 / G37 Factory Service Manuals - NICOclub



Here is a quick test for fuel pressure:

 

Hey Sonic, thanks for the info!

I removed and tested the fuel pump relay, its good; still no start though.

I spoke to him again last night and he had me test for fuel pressure exactly as you posted. Sort of anyways. I just hung the hose in a small container and tried to start my car. Fuel gushed out, looked clean, seems good.

He suggested that my crankshaft position sensors may be the issue. He said Nissan often has issues with failing sensors. He told me to swap them for ****s and giggles just to see if it would do anything (it didn't).

He recommend I first test my spark plugs and coils. They use iridium plugs which he said normally last a long time but you never know. He said a bad spark plug shouldnt cause my car to suddenly die without any warning. If that doesn't get it going, told me to change the crankshaft position sensors.

Im thinking it might be worth while just to take it down to an Infiniti shop and have them run a computer diagnostic on it to pinpoint whats wrong.

But, before I do that i'll check the plugs and coils on my day off. Will update.

Any info or suggestions are definitely welcome!

 

Generally, replacing parts without verifying they have failed is expensive and not usually successful. If I were you, I wouldn't buy cam or crank sensors hoping it will fix it.

If you have access to an oscilloscope, you could scope the crank and cam sensors to verify their waveform and crank/cam timing.

If you don't have a scope, I would take it to the dealer and let them figure it out.

I am not 100% certain, but if the cam/crank sensors are not as the
ECM expects (waveform & timing), it may not fire the coils. I suspect your chills are firing, since you said it tries to start.