I have a problem with my fuel system, in my 1984 fiero with the 2.5l , the pump doesn't prime when I turn on the key. I bypassed the relay to see if the pump was the problem but when I do I hear the pump running but even then there seems to be no gas coming out of the injector. So I changed the fuel pump relay thinking it was bad and it didn't solve the problem. I don't know where to look anymore, what is the problem?
Could be the piece of fuel line between the hard line and the pump split open. Happened to me. Pump was fine but the line connecting it to the hard line split. Either way you will be dropping the tank to replace. I installed a new pump anyway while I had the tank out. You have to use a special type of in-tank fuel line. Search function should locate it.
after further testing and having changed the pump, the car wont start but I have found out the by jumping the injector to send gas into the tb the car starts and runs fine afterwards, it seems as if the signal for the injector to send the first pulse of gas is not happening could it be a temporary relay ?
The ECM is supposed to turn on the fuel pump relay by sending +12v on the Dk. Green/White wire. Use a 12v test probe and see if you are getting +12v for two seconds when you turn the key to on. You should also get the +12v if you bump the starter till two seconds till after the engine stops.
You are saying the engine is running fine if you start it on some gas otherwise right?
My guess is the fuel pump relay isn't turning on, most likely caused by a bad ECM. The oil pressure switch can ALSO turn on the fuel pump. But if your Fiero has lots of miles it might not build up enough oil pressure to turn on that switch unless the engine is running.
Test with the test light. If your ECM is poop, you can buy one from someone here on the Forum. Only 84 ECMs will work in your 84. Also if the donor ECM is from an auto and you have a stick or vice versa you will have to swap the PROM chips in them.
But test with your test light first before replacing the ECM.
[This message has been edited by phonedawgz (edited 08-04-2013).]
I have heard about water running down the fuel pump wireing harness and rusting out one of the pins (located on the rear firewall). If you can get it running,thats probubley not your problem. Do you hear the fuel pump relay click when you turn the key.
Allso when you installed the new fuel pump,I hope you used small metal hose clamps on that little hose that poped off.
when I was jumping the injector yesterday to start the car I had removed the relay before hand and had forgotten to plug it back, the car would start anyways and when I did notice and plugged it back there was no change, and no I do not hear the relay click when I turn the key and I did put metal clamps on the little rubber hose in the tank.
what else does the ecm control ? because I would think that other thing wouldn't work no ?
also beneath my fuel pump relay there are two other relays what are they for are they part of the fuel system as well? I do not have a/c
There is a circuit on the ECM that runs the fuel pump relay control output. If you are not getting the +12v out of the ECM on the fuel pump relay activation lead then your ECM isn't sending the voltage on that lead. That would indicate a bad ECM.
The ECM also controls the injector, the ignition timing and the check engine light.
It is not unusual for an ECM to loose the fuel pump relay control circuit. The driver transistor that controls that output can fail and cause just the fuel pump relay to fail. But CHECK FIRST to see if the ECM is putting the voltage out on the Green/White wire that runs to the relay. You could have bad wiring. You could have a bad relay socket. You could have a bad relay. Or perhaps the ECM isn't putting the +12v out to the relay.
It all comes down to is if you are not getting the output on the correct pin.
84 Fiero uses the 1226156 ECM.
[This message has been edited by phonedawgz (edited 08-06-2013).]