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Fuel problem

Tiny
HARVEYHUMES
  • MEMBER
  • 1982 CHEVROLET CORVETTE
  • V8
  • AUTOMATIC
  • 175,000 MILES
Fuel pump is good. Weak power to pump. Does the ECM control fuel pump power or is there a relay somewhere other than the distributor. Swapped out ECM and same problem. Distributor and fuel pump are new. Does the resistor on the fuel delivery system inside the tank serve a purpose that would effect the delivery of fuel? It was running fine until I let it set for a couple of months over the winter. Thanks for any input you have. I am stumped.
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Wednesday, March 14th, 2018 AT 8:32 AM

22 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning.

What voltage is at the pump?

Did you check the pressure?
Is this the cross fire system?

Roy
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Wednesday, March 14th, 2018 AT 9:04 AM
Tiny
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Thanks for your response. Voltage is less than twelve. Yes, it is a cross-fire system. I do not have an inline tool to check the pressure.
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Wednesday, March 14th, 2018 AT 8:10 PM
Tiny
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Okay, you need to get a fuel pressure gauge. You can rent one at a parts store.

Yes, the ECM does power the pump but you need full battery voltage for the pump to work. Is the battery fully charged, it should be 12.6 volts.

Roy
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Thursday, March 15th, 2018 AT 3:52 AM
Tiny
MARTHA HUMES
  • MEMBER
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Have checked fuel pressure. 20# psi.
Have run wire from battery to fuel pump & fuel pump is working fine.
Injectors not opening.
Have checked relay & it’s good.
Fuel to injectors fine.
Used another ECM & same results.
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Thursday, April 5th, 2018 AT 1:00 PM
Tiny
HARVEYHUMES
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  • 11 POSTS
The above message is from Harvey to ASEMASTER6371
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Thursday, April 5th, 2018 AT 1:08 PM
Tiny
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OK,

the ecm quad drivers control the injector turning on and off.

Do you have spark?

Can you get a noid light and check and see if the ecm is commanding the injectors on?

Roy
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Thursday, April 5th, 2018 AT 1:12 PM
Tiny
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Yes! I've done that & node light is pulsing so commanding injectors.
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Thursday, April 5th, 2018 AT 1:15 PM
Tiny
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Ok, the ecm is good.

20 lbs for pressure is double the spec.
Do you know if there is fuel in the engine? Remove a plug and smell for fuel.
Do you have spark?

Roy
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Thursday, April 5th, 2018 AT 1:18 PM
Tiny
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Does one bad injector effect the other? I'm told it makes no difference because I'm getting fuel to both banks.
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Thursday, April 5th, 2018 AT 1:18 PM
Tiny
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Engine runs fine when fuel is present, i.E. When I prime the engine.
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Thursday, April 5th, 2018 AT 1:20 PM
Tiny
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You may be getting too much fuel. Like I said, 20 lbs is way to much and may be flooding the engine with fuel.

Did you check the ohms on the injectors?

Roy
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Thursday, April 5th, 2018 AT 1:22 PM
Tiny
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New WIX fuel pump for 1982 Corvette crossfire. 20# may not be true reading was done with a rented tester.
Injectors will drip fuel only.
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Thursday, April 5th, 2018 AT 1:23 PM
Tiny
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Ok, then something is not right.

If you have noid and you can make it run with priming, we need to recheck fuel delivery. The 20 makes no sense. You can have pressure and no volume.

Roy
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Thursday, April 5th, 2018 AT 1:24 PM
Tiny
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If they only drip, you have a pump issue. They should spray

Roy
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Thursday, April 5th, 2018 AT 1:25 PM
Tiny
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It could also be clogged injectors as well.

Roy
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Thursday, April 5th, 2018 AT 1:25 PM
Tiny
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Can't check ohms on injectors because there's no fuel stream. Nothing comes out of the injectors other than a drip. Is it possible the injectors can stick? And does one override the other?
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Thursday, April 5th, 2018 AT 1:26 PM
Tiny
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I have pressure and volume. Took fuel line off and its coming through fine.
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Thursday, April 5th, 2018 AT 1:29 PM
Tiny
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Ohm check is simple. Just check the resistance across the 2 terminals of the injector with the wire disconnected.

Yes, they can be clogged from either debris from sitting or carbon not allowing the pindles to move. It seems your next step is to replace the injectors.

Roy
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Thursday, April 5th, 2018 AT 1:34 PM
Tiny
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I rented the noid light tester from AutoZone and put the testers on the 2 terminals of carburetor; they flashed and pulsed as they should. That should satisfy the ohm check yes?

I've had this Vette since 1984 and I don't drive it in winter. It now has over 150K miles on it and maybe sitting for about 4-6 weeks during some very frigid weather pushed it over the limit. Man, they are a headache to troubleshoot when you have a problem.

The injectors are original equipment.
Do they have to be adjusted if I replace them?
Is #1 unit different from #2, and must I specify which unit I need?
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Thursday, April 5th, 2018 AT 1:41 PM
Tiny
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The noid just test the wiring. That is not an ohm test for the injector.

There is no adjustment when you install them. I would get the GM OEM as a pair.

The throttle bodies should be synchronized when done. That is done with a mamometer. Not many guys have that. I doubt even the dealer would unless they have a old timer like me working for them.

Roy
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Thursday, April 5th, 2018 AT 1:48 PM

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