84 electrical problems
Thread Starter
Instructor
Joined: Jan 2006
Posts: 173
Likes: 0
From: Cleveland Ohio
84 electrical problems
I am working on my fathers 84 Corvette. We replaced the engine and engine wiring harness. The car sat for a few years prior to replacing the engine. We went to start the car this weekend and it would just crank over. I checked the fuse going to the fuel pump and it only has power for about 2-3 seconds then nothing. No fuel getting to the throttle bodies. Is this normal? or should there be power all the time?
Also, we changed the relay for the cooling fan and now it stays on all the time. Even with the ignition off. More than likely it is wired directly to the battery, Or could it be something else.
Thanks
Gary
Also, we changed the relay for the cooling fan and now it stays on all the time. Even with the ignition off. More than likely it is wired directly to the battery, Or could it be something else.
Thanks
Gary
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Your fuel pump is operating normally. The ECM turns on the fuel pump for 2 seconds when you turn the ignition on. If the engine starts, a switch on the oil pressure line turns on the fuel pump at 4 psi oil pressure.
Your cooling fan is turned on by the relay and the ECM grounds one wire on the relay coil when it is told by the coolant temp sender that the coolant is at or above 228 F. You need to find out why the relay is on all the time. The other wire on the relay coil goes to the ignition switch and has 12v on it only when the ignition switch is on.
Your cooling fan is turned on by the relay and the ECM grounds one wire on the relay coil when it is told by the coolant temp sender that the coolant is at or above 228 F. You need to find out why the relay is on all the time. The other wire on the relay coil goes to the ignition switch and has 12v on it only when the ignition switch is on.
Burning Brakes
Joined: Sep 2006
Posts: 1,202
Likes: 3
From: MD
You need to prime the fuel system. Turn the ignition on for a few seconds at a time to pump fuel up to the TBs without trying to crank the motor. When the pump stops running, turn the ignition off and back on until there is fuel at the TBs. Should start then.
Racer
Joined: May 2006
Posts: 293
Likes: 0
Originally Posted by jfb
Your fuel pump is operating normally. The ECM turns on the fuel pump for 2 seconds when you turn the ignition on. If the engine starts, a switch on the oil pressure line turns on the fuel pump at 4 psi oil pressure.
