tim-92bird

Ok I am finally stumped! it’s a 92 firebird 305 tbi. The pervious owner replaced the fuel pump shortly before I bought the car so the pump is about 6 months old and has been working fine until now although I am unsure of his mechanical skills.


I adjusted the timing friday then jacked up the car when replacing the spark plugs. i took it for a short test drive parked it, had dinner and when I came back it would not start, the fuel pump was not coming on. A few hours later it still was not working. saturday morning I came out and figured I would give it one more try and it started right up. I started it 5 or 6 times saturday. Then saturday night my son and I changed the oil and the valve cover gaskets and I did jack it up again for the oil change although I can’t think of what jacking it up could do to the fuel pump but both times it has died right after being jacked up? When we were done I started it to check for leaks then turned it off, went and closed the hood and decided I would take my son for a ride I started it up again my son got in and slammed the door, the car immediately sputtered died. I went to restart it and the fuel pump again would not come on. So like an idiot I went over and slammed the door again to see if maybe it would fix it no such luck. I have power at the fuse and the fuse is good. I have power at the orange wire at the relay, and I have power at the grey wire at the relay when key is turned. I have not checked the wires under the car yet because it is now dark and raining. My first thought is a lose connection some where but where? Is there something else I should be looking for? the battery is crap but the car was running last time it died so i don't think thats it. it is reading .829 to .800 on the meter set to 10 mega ohm DCV at the fuse with the key on, that seems a bit low to me but i can't find what it should read. I did have an engine code a week or two ago when I checked for codes and it was low voltage at the fuel pump but since it was working fine at the time and I don’t know how old the code was I ignored it. maybe a weak ground wire somewhere? sorry for the long post thanks for any help/ideas.

rgarcia63

Start with replacing, or testing/charging the battery.

Supervisor42

Well, the good news is that the guy probably sold you the car because he couldn't find what was causing the fuel pump not to run, sometimes.
So you have a car with a new fuel pump (everyone else that has the original pump in their 3rd gen wonders when it will die).
You should find the fuel pump relay and swap it with another relay under the hood that is just like it and eliminate it as the problem.
Atleast you're lucky that it doesn't run now. If it works most of the time it can be a bear to troubleshoot.
It sounds like a bad connection and here is where the ground to the F/P relay should be. It's bolted to the back of the driver's side head (pain to access).
Make sure there isn't a broken wire and the bolt to the head is tight.
The F/P should only run for 1.5 seconds at key-on. Key has to be off for over a minute before it will run at key-on again.
Here's a pic of the ground wires:

tim-92bird

Thanks everyone, I checked on it this am and the fuel pump still isn’t kicking on And now it has a dead battery. So I throw it on the charger. When it is done I will check that ground wire if it is intact then I will try stealing a battery out of one of my other cars. I could have knocked that ground looses, in the last month off the top of my head I have replaced the full exhaust, water pump, thermostat, radiator hoses, intake manifold gasket, valve cover gaskets, plugs, wires, breaks, rebuilt the tbi, changed all the fluids/filters, fixed the timing (it was WAY off), most of the vac lines, window motors…….. Good news is I had it running pretty good until this.

tim-92bird

Ok here’s an update, I checked all the wires. The last one I checked was the connection above the rear diff it had power on the purple wire only. I plugged the connection back in and the tried the key again and the pump worked again. The car started but ran like **** back fired then died. I tried the key again and once again the pump would not come on so I plugged and unplugged and replugged the connection 5 or ten times until the pump worked again this time the car stayed running so I am guessing it is in the connection but the harness to the pump is also new replaced by the last owner when he did the pump and the connection looks good, fits snug…. The idle has also dropped to about 500 rpm and it’s running rich with a weak spark I guessing there is something in the electrical system that’s not happy right now. I am going to take that suggestion of a new battery before I do anything else since I know that it’s weak, and have the coil tested. Thank god this is an extra car so I can still get to work tomorrow. Thanks again for the help.