The swap has been going well and the 4.9 has been firing up every single time until yesterday. I had been remounting the overflow tank due to a broken tab. I started it up, backed it out of the garage and was going to let it get hot and make sure the cooling system was working properly. And after about 5 minutes, it just died. No warning, it just died, and it will not start again. Thoughts? FYI, its an '86 GT with a '92 4.9, new fuel pump, fuel lines, and fuel filter. Thanks in advance!
Start by narrowing it down. Check if your fuel pump is running when you turn the key, then check you are getting fuel pressure (you'll need an inline fuel pressure gauge...they are cheap). If you are then you can move over to the electrical side and start there. (I'll wait until you know if it is fuel or electrical before next diagnostic steps)
EDIT: Don't assume something works just because it was changed. And...don't start throwing money at it by changing every part. You'll just introduce more problems.
[This message has been edited by Neils88 (edited 06-26-2015).]
Have the ignition control module tested. Most auto parts stores will do it for free. These controls modules aren't as likely to fail as a fiero one but it still does happen. Its one of the more likely problems for a 4.9 that suddenly stops running and it doesn't cost anything to find out for sure.
Hi everyone! I apologize for taking so long to reply. Had another incredibly busy weekend. But THANK YOU for the ideas. I'll start checking things either tonight or tomorrow and will report back . Thanks again! This forum rocks!
I finally had a chance to take a look at the car. Everything looks right, nothing out of place, everything connected, fuses are all good. When I place a few drops of gas into the throttle body it will start, but die after a few seconds. Can I assume it's the pump? When I listen to hear the pump prime as I turn the key, I don't think I hear it, but I'm not 100% sure.
Good chance the pump isn't running. However, could be the pump, blocked fuel filter, failure of the hose in the tank (common if it has sat for any length of time), fuel pump relay failure, or an ECM problem. There is also a chance that it is still electrical, and the injectors aren't firing. I don't have the wiring diagram handy, so hopefully someone else can jump in, but I'd start by hooking directly to the pump through the connector located near the passenger side lid hinge. I can't remember which wire is which, but one is ground, one is the +12V to the pump, and the last one is the fuel level sensor. If the car runs after that, then it is likely a relay problem (though less likely, it could be a faulty ECM). If it won't start, you should hook up a fuel pressure gauge and confirm your pump is working properly.
I'd make sure the pump was getting power before doing the pita job of dropping the tank.
All kinds of things can cause the fuel not to be delivered to the engine.
Does your check engine light come on key on engine off? Does the fuel pump sound like it is running? Remove the fuel pump relay and jumper the Orange or Orange/Black wire to the Tan/White or Tan wire. Does the fuel pump now run? If so it's not the fuel pump that is the problem.
