84 Vette needs help
Thread Starter
7th Gear
Joined: Jun 2014
Posts: 7
Likes: 0
84 Vette needs help
My 84 Vette will not idle and the engine will not run at any steady rpm unless the accelerator is continuously pumped. It is not drivable. When I drove it a week earlier everything was fine. This started all of a sudden as I was pulling out the drive. I replaced the fuel filter, rotor, distributor cap, and coil, and there are no problem codes stored in the ECM. The same amount of fuel appears to be coming from both injectors.
I had my friend make this video while I was able to keep it running.
Any and all suggestions will be appreciated.
I had my friend make this video while I was able to keep it running.
Any and all suggestions will be appreciated.
Thread Starter
7th Gear
Joined: Jun 2014
Posts: 7
Likes: 0
Gauge shows 1/4 tank, but I will add a few gallons too be sure. I'll get a fuel pressure gauge and check that. Manual says it should be 9 to 13 psi. Before this problem I've only observed the injectors at idle speed, but with my friend pumping the accelerator quite a lot of fuel was coming from both injectors.
Thanks, this will be a good check to perform. I'll post what I find.
Thanks, this will be a good check to perform. I'll post what I find.
Thread Starter
7th Gear
Joined: Jun 2014
Posts: 7
Likes: 0
Thanks,
I just got a loaner fuel pressure gauge from Autozone. They charge for loaner tools and give 100% refund if it is returned within 90 days. Depending on what find with the fuel pressure, I'll be checking the TPS. Not only will it not idle, but it won't run at any engine speed unless the accelerator is pumped. If I stop pumping and hold the accelerator 1/2 way, or even floored all the way, it will die within 2 seconds.
Thanks for the suggestion.
Gordon
I just got a loaner fuel pressure gauge from Autozone. They charge for loaner tools and give 100% refund if it is returned within 90 days. Depending on what find with the fuel pressure, I'll be checking the TPS. Not only will it not idle, but it won't run at any engine speed unless the accelerator is pumped. If I stop pumping and hold the accelerator 1/2 way, or even floored all the way, it will die within 2 seconds.
Thanks for the suggestion.
Gordon
Racer
Joined: Dec 2003
Posts: 277
Likes: 3
My 84 Vette will not idle and the engine will not run at any steady rpm unless the accelerator is continuously pumped. It is not drivable. When I drove it a week earlier everything was fine. This started all of a sudden as I was pulling out the drive. I replaced the fuel filter, rotor, distributor cap, and coil, and there are no problem codes stored in the ECM. The same amount of fuel appears to be coming from both injectors.
I had my friend make this video while I was able to keep it running.
84 Vette sympton - YouTube
Any and all suggestions will be appreciated.
I had my friend make this video while I was able to keep it running.
84 Vette sympton - YouTube
Any and all suggestions will be appreciated.
Thread Starter
7th Gear
Joined: Jun 2014
Posts: 7
Likes: 0
Thanks,
I will check it out. I do have the loaner fuel pressure gauge, and will test that before pulling the fuel pump for inspection. Depending on what I find with the pressure I "may" get a new pump before pulling the old one. I think it is a $40 part.
I will check it out. I do have the loaner fuel pressure gauge, and will test that before pulling the fuel pump for inspection. Depending on what I find with the pressure I "may" get a new pump before pulling the old one. I think it is a $40 part.
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Melting Slicks
Joined: Dec 2009
Posts: 2,232
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When you test the fuel pressure, do a dead head test too. This is when you pinch off the section that continues up after the gauge, see if it spikes to 18(?) psi & holds.
Make sure the egr valve isn't getting vacuum at idle too.
Make sure the egr valve isn't getting vacuum at idle too.
Thread Starter
7th Gear
Joined: Jun 2014
Posts: 7
Likes: 0
Yes,
My shop manual says if pressure less than 9 psi to:
Ignition off
Disconnect both injectors
Pinch return line flexible hose
Apply 12 volts to ALCL terminal G
Then if above 13 psi, replace rear injector Fuel Meter Cover.
The manual does refer to this as the Dead Head Test.
If the psi is less than 9, I think I'll first do as you suggest and just pinch the return line and see if the psi spikes above 13. I'm a little reluctant to apply 12 volts to the terminal G, but I guess all that does is turn on the fuel pump with everything else turned off.
My shop manual says if pressure less than 9 psi to:
Ignition off
Disconnect both injectors
Pinch return line flexible hose
Apply 12 volts to ALCL terminal G
Then if above 13 psi, replace rear injector Fuel Meter Cover.
The manual does refer to this as the Dead Head Test.
If the psi is less than 9, I think I'll first do as you suggest and just pinch the return line and see if the psi spikes above 13. I'm a little reluctant to apply 12 volts to the terminal G, but I guess all that does is turn on the fuel pump with everything else turned off.
Thread Starter
7th Gear
Joined: Jun 2014
Posts: 7
Likes: 0
It was the fuel pump.
Yes,
My shop manual says if pressure less than 9 psi to:
Ignition off
Disconnect both injectors
Pinch return line flexible hose
Apply 12 volts to ALCL terminal G
Then if above 13 psi, replace rear injector Fuel Meter Cover.
The manual does refer to this as the Dead Head Test.
If the psi is less than 9, I think I'll first do as you suggest and just pinch the return line and see if the psi spikes above 13. I'm a little reluctant to apply 12 volts to the terminal G, but I guess all that does is turn on the fuel pump with everything else turned off.
My shop manual says if pressure less than 9 psi to:
Ignition off
Disconnect both injectors
Pinch return line flexible hose
Apply 12 volts to ALCL terminal G
Then if above 13 psi, replace rear injector Fuel Meter Cover.
The manual does refer to this as the Dead Head Test.
If the psi is less than 9, I think I'll first do as you suggest and just pinch the return line and see if the psi spikes above 13. I'm a little reluctant to apply 12 volts to the terminal G, but I guess all that does is turn on the fuel pump with everything else turned off.
Problem resolved.
I installed a new Delco fuel pump EP386. Actually, the original strainer was in pieces and the 2 inch rubber hose that connects the pump to the metal gas pipe was severely deteriorated. The old pump may have been usable, but I was afraid some of the strainer material may have gotten into the pump and no sense risking doing this twice for the cost of the pump. After all, the old pump was 30 years old. The idle is much higher than before this problem started, but it runs great. I only drove it down block and back and did not let it warm up to normal temperature.
Thanks to all for the suggestions and help.