I just recently bought an 84 firebird and after working on nothing but classics imports i am at a loss. Things i can say.... I do not hear the electric fuel pump at all. I have tried replacing the fuel pump relay. the coil has been changed. I have been told it could be the ignition module but i am not exactly sure where that is placed in this car. the car runs for about ten minutes before killing itself and i have to wait for it to cool down before it will start again. any help would be appreciated.

 

The 84 Firebird will have a mechanical pump down on the front passenger side of the block unless it's been swapped for an electric pump.

Some of the 84's, 85's with carbs have been fitted with in tank "helper" pumps, to assist with vapor lock issues but they only run 2psi or so to assist the mechanical pump on the block. Mine was like this. My intank pump was totally dead, even with power supplied. So ify ou have a mechanical pump on the block (runs off the cam so only runs when the engine is turning over), you won't hear the electric pump if it's dead.

Can you tell us a bit more about your car?

Engine, carb/efi swap, anything that the previous owner may have done to it?

Sounds like it coold be vapor lock from fuel boiling in the lines, but I ran mine for years without having any issues on just the mechanical pump on the block.

 

It has the 305 v8 and it is carbed. I didn't see a mechanical pump on it but i didnt look long and it is a little more cluttered than I am used to. I will check tonight. Any suggestions on how to test if it is vapor lock and how to remedy it?

 

Just throw a flashlight down on the front passenger side and you should see a pump with hoses going to it attached to the block. Alternately, follow the fuel line down from the carb, it'll have one line headed strait to the pump. The pump will have three lines on it. ONe in, one to the carb and one return line.

Vapor lock is cured by two things. Keeping the fuel cool or an electric in-tank pump/inline pump. Sometimes both. With an electric pump vapor lock is much less likely because you are constantly pushing "new" fuel from the tank through the lines and even if an airbubble gets caught in the carb, the new fuel will replace it fast enough to keep the bowls full.

With a mechanical pump that "pulls" on the rotation of the motor (rod runs to the cam which pushes it against a lever in the pump creating the pumping action), can get stuck when the airbubble reaches the pump. There is nothing but "air" in the pump which can then not pull any more fuel because it lost it's suction. Only way to cure this is to shut the motor of and let it cool down so the air bubble will work its way out.

 

Alright I did find it after snaking my my passed the emissions crap. Also bought an aftermarket fuel pump thatruns 4 to 7 psi. Going to install tomorrow. Happy Easter BTW.

 

Well I haven't gotten around to installing the electric pump. After putting my ignition module back it and plugging my spark plug wires back on the cap I noticed a wire was unplugged from the distributor. I for the life of me can't remember if this was unplugged before hand ( I am assuming it was unplugged the whole time) After plugging this in it started right up and sat running for a good 15-20 minutes, which is a fair amount longer than it was. the idle was fine and didnt climb up before dying like it was. I did however run out of gas. haha could it be possible for the car to even run without all the wires hooked up?

 

It would need most of them to have enough spark to fire the cylinders. But the answer is yes, it will run without all hooked up, it'll just run like crap because one or more cylinders won't be firing.

 

well all the spark plug wires were hooked up (they are still the original) it was one of the actual wires that hae a clip the get plugged in the bottom of the distrib.

 

I've never heard of an any carbed third gen with a fuel pump in the tank.That wasnt a factory installed option was it? Someone would have to be nuts to go through the work of dropping the axle,exhaust,and tank if they didnt have too.
Thats one of the biggest annoyances of TBI and TPI cars.GM didnt bother to make an access panel in the hatch area to get to the pump easily.

I've had a couple early Trans ams with carburetors and never had vapor lock issues even during the summer.I didnt realize that was such a problem.

 

Hmm. It would have to be the four wire connector at the base that was disconnected. The car wouldn't run with any of the other wires disconnected. That connector basically carries the circuits between the ECM and the ICM. The electronic spark timing functions over these circuits. The ECM also receives the crank reference signal over one of the circuits. The car would run without these circuits connected but would not achieve closed loop fuel control and would not have EST(timing would be default timing curve in the ICM). If the connector was off, it may be due to an issue with the computer command control system that someone was trying to get around. Guess you'll know soon enough.

 

Some of them have little helper pumps. Also for further information this is trans am model.