Suddenly; no fire

Hey guys, suddenly, my SC L32 that came out of a 2006 Grand Prix wont' start.  Can you give me some idea where to look first?   I've had this car 2nd hand for 2 months and it has started up and ran like a clock.  I drove it today for 2 short trips and it acting normally.  Then a short time later I came out to go again and it started weakly, only got to 5 or 600 RPMs then died quickly.  Playing around with pumping the throttle, holding it wide open, not touching it at all (as it has always started right up).......all of those things made no difference;  Well,  pumping and holding it wide open kept it from even coughing a little.  Of air, fuel and spark, it seems like it's not getting proper fuel.  Am I getting warm?  what's the first thing to check?  

BTW, lately the idle has begun "hunting" at stop lights;  cycling between 300 and 1500 RPMs and occasionally dying.  Is that part of it?

Tank is nearly full; the 2 big filters coming out of the tank are clean. Is there another screen or filter to check?

Any help or ideas would be appreciated.

Ted, can you lay hour hands on an OBD 2 reader that can read out trouble codes? That's where I'd probably start. With so many sensors and electronics involved these days it's hard to say what might be causing it.

-Dave

Yeah, good idea. I should get one and learn how to use it.

Well, it's clear the pump is not pumping. No sound and no fuel to the regulator. Not sure I'm getting power to the pump though. All the fuses look OK so I guess I need to look for a loose connection.

Another reason I don't think it's the pump is that the pump and tank gauge are on the same circuit and there's no gauge reading.

In addition to the fuse, depending upon how your car is wired Ted there may also be a fuel pump relay and/or a fuel pump switch on the dash. Those items would have been at the discretion of the builder so they may or may not be there.

-Dave

thanks No switch but will look at the fuel pump relay; gotta have one for any fuel injection system, right?

Ted FM 13 wrote:thanks  No switch but will look at the fuel pump relay;  gotta have one for any fuel injection system, right?

Yip, look for a relay b/c no ECU will be able to directly source 10-20A of current required for the pump.

For your fuel level gauge, it's unlikely that the gauge is also on the switched side of the fuel pump relay, but you never know. Typically, gauges would simply get 12V ignition power. If your other gauges are working, then if there is an easy way to verify that you're getting 12V all the way to the gauge, then you might have a faulty gauge or your sender wire may have an issue somewhere.

You might also check your ground connections for the pump & sender, especially if they share a ground connection. This would account for both ceasing to function even if they are on different 12V circuits.

First get an ECM reader they're around $70 at an auto parts store. With that you will know weather or not the ECM is getting power and if it is are there any codes. It sounds like a simple no power problem. If the ECM is not powering up then start at the key switch and work out from there. You'll need a volt meter also. Remember your fuel pump only runs for a few seconds then shuts off if the engine is not running.


Brian

Well I finally got around to looking for a short or lost ground or............??.  Looked and tested the relay that was marked "fuel pump, lights ...".  It was one of 3 relays behind the steering wheel and gauge panel.  It was good.  Then, I just happened to notice another relay in the engine side of the "firewall" which had a loose connector.  Zipped tied it back in, labeled it and varoom,  car back to life.