will not run
Advanced
Joined: Aug 2007
Posts: 62
Likes: 0
I don't know the fuel pump control well, but I believe that when you turn on the key to the on position, the ECM sends power to Terminal C of the relay. Terminal C is power supply to the relay coil. This closes the connection from Terminal E to Terminal A. Terminal A is the power supply to the fuel pump. This happens for 2 seconds and Terminal C stops getting power from the ECM. The "shot" of gasoline is enough to start the engine, then there is enough oil pressure to close the contacts on the oil pressure switch and continue sending power to the fuel pump via the oil pressure switch.
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
You will only have power on the pump fuse if the pump is running or you have jumpered the relay connector.
You say the car starts on the OP switch so you obviously have pump power through the fusible link to the OP switch and at the relay (E )
What you should be concentrating on is why you have no power on C ( that operates the relay ) when the key 1st turned on or when the engine is running
Have you checked the voltage at C with the engine running?
edit.
The pump is running off the OP switch so you can leave the relay disconnected and probe terminal C in the relay connector to ground with the engine running.
You say the car starts on the OP switch so you obviously have pump power through the fusible link to the OP switch and at the relay (E )
What you should be concentrating on is why you have no power on C ( that operates the relay ) when the key 1st turned on or when the engine is running
Have you checked the voltage at C with the engine running?
edit.
The pump is running off the OP switch so you can leave the relay disconnected and probe terminal C in the relay connector to ground with the engine running.
Last edited by vetteoz; Oct 13, 2013 at 11:00 PM.
Safety Car
Joined: Sep 2004
Posts: 3,953
Likes: 550
From: Mission Viejo CA
It looks to me like you're getting bogged down in chasing electrical questions, without a good understanding of electrical stuff. A really nice feature of the '84 Corvette is that you can watch the fuel injectors work!
I'd suggest a really simple test:
1. Remove the top cover of the air cleaner.
2. Run a jumper wire from +12 v. directly to your fuel pump fuse. You should hear the fuel pump should run.
3. Try starting the car while you are watching the fuel injectors. You should see a continuous spray from both injectors.
4. If you don't see a continuous spray, you probably have low fuel pressure, possible because of a clogged fuel filter or a bad fuel pump, even though the pump is new.
I'd suggest a really simple test:
1. Remove the top cover of the air cleaner.
2. Run a jumper wire from +12 v. directly to your fuel pump fuse. You should hear the fuel pump should run.
3. Try starting the car while you are watching the fuel injectors. You should see a continuous spray from both injectors.
4. If you don't see a continuous spray, you probably have low fuel pressure, possible because of a clogged fuel filter or a bad fuel pump, even though the pump is new.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
I don't know the fuel pump control well, but I believe that when you turn on the key to the on position, the ECM sends power to Terminal C of the relay. Terminal C is power supply to the relay coil. This closes the connection from Terminal E to Terminal A. Terminal A is the power supply to the fuel pump. This happens for 2 seconds and Terminal C stops getting power from the ECM. The "shot" of gasoline is enough to start the engine, then there is enough oil pressure to close the contacts on the oil pressure switch and continue sending power to the fuel pump via the oil pressure switch.
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,464
Likes: 48
It looks to me like you're getting bogged down in chasing electrical questions, without a good understanding of electrical stuff. A really nice feature of the '84 Corvette is that you can watch the fuel injectors work!
I'd suggest a really simple test:
1. Remove the top cover of the air cleaner.
2. Run a jumper wire from +12 v. directly to your fuel pump fuse. You should hear the fuel pump should run.
3. Try starting the car while you are watching the fuel injectors. You should see a continuous spray from both injectors.
4. If you don't see a continuous spray, you probably have low fuel pressure, possible because of a clogged fuel filter or a bad fuel pump, even though the pump is new.
I'd suggest a really simple test:
1. Remove the top cover of the air cleaner.
2. Run a jumper wire from +12 v. directly to your fuel pump fuse. You should hear the fuel pump should run.
3. Try starting the car while you are watching the fuel injectors. You should see a continuous spray from both injectors.
4. If you don't see a continuous spray, you probably have low fuel pressure, possible because of a clogged fuel filter or a bad fuel pump, even though the pump is new.
what I do not understand is why I cannot get the pump to run off terminal G on the ALDL.
I will use your suggestion and thank you
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,464
Likes: 48
UPDATe
I took a look at diagram 8A and realized that the relays and connector for the fan and the fuel pump were switched.
I then used the Ohm meter and everything is working correctly. I started the car and checked the Fuel pump fuse. It has power. The crank fuse still does not have power.
I could not run the pump through terminal G or by running voltage to the fuel pump fuse.
But the car is starting better, I guess next week I will look at the crank fuse.
Thank yuo all for you patience and assistance.
I took a look at diagram 8A and realized that the relays and connector for the fan and the fuel pump were switched.
I then used the Ohm meter and everything is working correctly. I started the car and checked the Fuel pump fuse. It has power. The crank fuse still does not have power.
I could not run the pump through terminal G or by running voltage to the fuel pump fuse.
But the car is starting better, I guess next week I will look at the crank fuse.
Thank yuo all for you patience and assistance.
