hard starting/dies while in motion

[crankgrinder]

2oo2 pontiac sunfire s.e. hard to start sometimes and car cuts itself off while moving down the road. Ill stop, put it in park ,then it may or may not be hard to start after that but so far so good it has restarted every time its done this. Turns over strong, doenst turn slow or weak as if with low voltage. Both fuel filter and fuel pump relay have been replaced thus far. Car also has new plugs and wires and a new tensioner, belt,idler pulley and battery. I am suspecting a fuel pump getting weak but am trying to rule out other causes before throwing a 250+ dollar pump assembly at it plus dropping the tank and all. What do you think about this? please help.

[Jason/RKBA]

It could be a few things. I would change the fuel filter then have the fuel pressure checked. The hard start could be the FPR or coils. If its running kind of sluggish the cam sensor could be failing but I doubt it. Have it scanned to see if its throwing any codes.

[crankgrinder]

Thank you. The fuel filters replaced, along with the relay and i am working on checking the pressure(this car requires a T-settup). Meanwhile i may speculate on an IAC ordeal or a pressure regulator. or maybe a fuel pump module situation? I notice that this car only does this at low idle. Hasnt done it yet at a full head of speed. times like when youre rolling up the driveway or putting down residential streets. I think ill also clean the TBI and linkage with intake spray. What do you think about this? any input is much appreciated.

[Jason/RKBA]

IAC is possible, they can be cleaned here is a link from a Subaru forum but it should still apply. Its hard to say about the fuel pump without knowing what kind of pressure you are getting. Good luck and keep us posted.

http://forums.nasioc.com/forums/showthread.php?t=781242

[crankgrinder]

Thanks again. The IAC seems to be doing its job, the throttle body and the IAC both have been removed and cleaned well. The car has not died while in motion since but now has become very difficult to sart.As of 10:30 this morning the Fuel pump primes @ 46 psi and drops to 28lbs after 20 minutes sitting there and the car runs almost right at 50 lbs and holds steady while running. But at 12:00 pm i go out and turn the key to the on position but do not start the engine and hear little buzz coming from the pump relay in the box under the hood (the one that looks like a big fuse).Only that relay has been replaced as well. The system only primes to about 25 psi which will not start the car. I tried this repeatedly and four or five times in a row it has done this. Starting to look more like a fuel pump problem again, but it could also be an electrical issue. dont think ill know for sure until i get paul to hook up the diagnostic computer and/or change the pump unit out. Thank you very much for your help and suggestions. You people are so helpful. If you have any more comments/suggestions please post.

[crankgrinder]

I fully appreciate your help and suggestions.l took it down to pauls and they hooked up the computer and found out that a bad connection in the steering column next to the starter switch was causing the fuel pump relay to recieve insufficient voltage to power the pump. As i went down the road the wires would jiggle a little bit and cause the voltage to the relay go up and down causing low and rough idle through the fuel pump itself. An ignition switch is what we thought the problem was but found the connection as we got down into it. Sure am glad it wasnt that fuel pump or PCM. thanks for the help.

[Jason/RKBA]

Wow I don't know if I would have ever thought of that one. I'm glad you got-r fixed and it didn't cost you an arm and a leg.