84 no fuel issue
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Heel & Toe
Joined: Jan 2005
Posts: 21
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84 no fuel issue
My 84 vette has a no fuel issue. It all started as I was driving it and I felt a few hesitations before it just died on the road. After about five minutes I was able to restart it and drive a few more miles before it would hesitate and stall again. Finally had it towed home after sitting for a couple hours but it would not start this time.
No matter what I have tried, I do not see any fuel coming out of either injector. The car will crank and will briefly run with starter fluid. When I turn the key to accessories, I do not hear the fuel pump kick in for two seconds and see no change in the fuel pressure.
If I jump the "G" terminal in the ALCL Connector I can hear the pump active and I do see the fuel pressure go up to 13.
Fuel pump and Fuel Pump relay are new. Plug in to Fuel pump relay was gunked up with old dielectric grease so I cleaned it out best I could and plugged into the new relay.
Would appreciate any suggestions as to which direction to keep looking. I plan to test more as specified in the FSM but can only go as fast as my wife is available as many of the tests are much easier with two.
Thanks,
Scott
No matter what I have tried, I do not see any fuel coming out of either injector. The car will crank and will briefly run with starter fluid. When I turn the key to accessories, I do not hear the fuel pump kick in for two seconds and see no change in the fuel pressure.
If I jump the "G" terminal in the ALCL Connector I can hear the pump active and I do see the fuel pressure go up to 13.
Fuel pump and Fuel Pump relay are new. Plug in to Fuel pump relay was gunked up with old dielectric grease so I cleaned it out best I could and plugged into the new relay.
Would appreciate any suggestions as to which direction to keep looking. I plan to test more as specified in the FSM but can only go as fast as my wife is available as many of the tests are much easier with two.
Thanks,
Scott
Safety Car
Joined: Sep 2004
Posts: 3,953
Likes: 550
From: Mission Viejo CA
Do you have the FSM? See pg. 8A-21 (Electrical section).
Since you can force the fuel pump to run by jumpering ALDL pin G, does the engine start?
How are you measuring the 13 psi fuel pressure? Do you have no fuel at the injectors even when you are measuring 13 psi when cranking the engine? Does your technique allow fuel to flow to the injectors during the pressure test?
If the oil pressure switch is good, the engine should eventually start, even if the fuel pump relay or its wiring is bad.
You should have 12 v. at the fuel pump fuse when:
1. Two seconds after turning on the ignition.
2. Jumpering 12 v. to ALDL pin G.
3. Cranking the engine after oil pressure builds.
It's nice to have a sharp wife!
Since you can force the fuel pump to run by jumpering ALDL pin G, does the engine start?
How are you measuring the 13 psi fuel pressure? Do you have no fuel at the injectors even when you are measuring 13 psi when cranking the engine? Does your technique allow fuel to flow to the injectors during the pressure test?
If the oil pressure switch is good, the engine should eventually start, even if the fuel pump relay or its wiring is bad.
You should have 12 v. at the fuel pump fuse when:
1. Two seconds after turning on the ignition.
2. Jumpering 12 v. to ALDL pin G.
3. Cranking the engine after oil pressure builds.
It's nice to have a sharp wife!
Last edited by Hot Rod Roy; Aug 29, 2015 at 02:31 AM.
Thread Starter
Heel & Toe
Joined: Jan 2005
Posts: 21
Likes: 0
Do you have the FSM? See pg. 8A-21 (Electrical section).
Since you can force the fuel pump to run by jumpering ALDL pin G, does the engine start?
How are you measuring the 13 psi fuel pressure? Do you have no fuel at the injectors even when you are measuring 13 psi when cranking the engine? Does your technique allow fuel to flow to the injectors during the pressure test?
If the oil pressure switch is good, the engine should eventually start, even if the fuel pump relay or its wiring is bad.
You should have 12 v. at the fuel pump fuse when:
1. Two seconds after turning on the ignition.
2. Jumpering 12 v. to ALDL pin G.
3. Cranking the engine after oil pressure builds.
It's nice to have a sharp wife!
Since you can force the fuel pump to run by jumpering ALDL pin G, does the engine start?
How are you measuring the 13 psi fuel pressure? Do you have no fuel at the injectors even when you are measuring 13 psi when cranking the engine? Does your technique allow fuel to flow to the injectors during the pressure test?
If the oil pressure switch is good, the engine should eventually start, even if the fuel pump relay or its wiring is bad.
You should have 12 v. at the fuel pump fuse when:
1. Two seconds after turning on the ignition.
2. Jumpering 12 v. to ALDL pin G.
3. Cranking the engine after oil pressure builds.
It's nice to have a sharp wife!
I was watching the oil pressure guage and it said the oil pressure was above the 4 psi that the oil pressure switch should kick on. I know that the gauge gets its oil pressure measurement from somewhere different than the switch but shouldn't the fuel pump turn on for two seconds when the key is turned to accessories even if the oil pressure switch was bad?
I'm going to redo the measurements again tomorrow at the fuse as I didn't measure them correctly the first time but am expecting to see no voltage except when I jump the "G" pin on the ALDL,
I guess at this point I'm expecting the voltage to be there for #2 but not for #1 or #3 but I'll verify that tomorrow.
I have the 84 shop manual but it goes from page 7C-9 to 8B-1. Not sure what happened to section 8A???
Thanks for your reply, sometimes it takes another set of eyes on the situation to help solve the issue.
P.S. Agree on the sharp wife!
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
Here's 8A-21 and I included the power diagram for the fusible link that powers the OPS and also the fuel pump relay
Last edited by WVZR-1; Aug 29, 2015 at 04:02 AM.
Thread Starter
Heel & Toe
Joined: Jan 2005
Posts: 21
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Thanks for the diagrams WVZR-1. Your comments made me look into the fusable link a little more so I tested the "E" terminal in the feul pump relay harness connector and it showed voltage. I then tested between the "B" and E" terminals and they also showed voltage. I then performed terminal "C" of the harness and ground when turning the ignition to on but didn't get any voltage this time. I'm moving on to testing the ECM next.
I couldn't test the voltage on the fuel pump relay as the weather turned we here in the Northwest and I couldn't push the car out of the garage to have enough room to open the passenger door to access the fuse panel.
Thanks for the help,
Scott
I couldn't test the voltage on the fuel pump relay as the weather turned we here in the Northwest and I couldn't push the car out of the garage to have enough room to open the passenger door to access the fuse panel.
Thanks for the help,
Scott
