Tuned, and now fuel problems

[geddytrams]

So i got the car tuned with an S-AFC and pulled 321 AWHP and 256 lb-ft TQ. A few days later, i went to get gas and after filling the tank i went to start it again and the engine cranked and cranked but wouldn't start. I managed to push the car out onto a road with a slight downhill and roll started it, and got it to start. I drove the car a while down the highway, stopped somewhere, went back out, and it started right up. Later that same day, a few good start ups later, i tried to start it and got nothing. Now all it does is crank. i have an aeromotive FPR with a fuel pressure guage, and the guage isn't reading any fuel pressure. Anyone have any idea what could be wrong with it? thanks for any help.

 

[daves06r1]

Ive got the same fpr and it doesnt show any fuel pressure with the engne off. Also if the car sits for about an hour or more it has to crank for a good 3-5 seconds before starting cause all the fuel bleeds off. But it does start. I saw some guys on here saying it was pretty much just something you have to deal with. I also get a vibration or burping noise through my return line sometimes and it doesnt do it with oem fpr on, have you ever noticed that?

 

[geddytrams]

Well no, what i meant was i don't get any fuel pressure while it is cranking. and normally if the engine is turning over, and the fuel pump is running, you will see fuel pressure. Also, i have a 255 walbro fuel pump, which is loud enough to be heard when you first turn over the key and it pressurizes the lines, but i can't hear anything, so i'm not sure the fuel pump is running at all.

 

[nates6969]

Ok so here are some things to check or possible causes:

Try unplugging the fuel pump harness under the back seat and manually wiring 12v to the pump wire..see if this starts the pump...if it does, leave it wired and try to start the car...if it starts you must now determine why the pump is not getting power...this could be because your MPI relay is going or I know on my 1g, the ECU caps leaked and corroded the fuel pump circuit but I would say thats worst case scenario. I can't remember the exact procedure for testing that relay but definitely look into it.

Also you obviously have a logger, I'm not sure if the 2g logger can do this but on the 1g you can go into diagnostics in most logging software, mmcd for example, and manually test the fuel pump curcuit with the key in the on position...check that out too

 

[geddytrams]

I'll test the relays, and pray the pump itself hasn't gone up. Could the ECU alone cause the fuel pump to not run even if the circuit hasn't corroded? thanks for your help

 

[nates6969]

Well I doubt the ECU is toast if the PCB is clean but it could of shorted if there was an overload for some reason...I doubt this though...If the board is clean, check the the MPI relay and test the pump...Trust me, you want one of those to be blown rather than your ECU!!

 

[nates6969]

hey I just came across this thread...its on testing the mpi, check it out

http://dsmtuners.com/forums/showthread.php?t=263224

 

[geddytrams]

What about the fuel pump? If the fuel pump was the problem, would there be any way to test it?