1986 Corvette Ignition problem

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Jul 11, 2011 | 04:53 AM

#21

Cliff Harris

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From: Anaheim CA

You definitely have a fuel system problem. It could be a bad fuel pressure regulator or leaking injectors. Your pressure is dropping way too fast. I haven't watched my fuel pressure gauge but you should still have SOME pressure after 30 minutes. I've seen people claim they still had 30 PSI after several hours, but I have difficulty believing that...

You said you replaced the pickup coil. That's the one that you have to remove the distributor shaft to replace. I have heard that they crumble, though mine was fine when I checked it. I have also heard that non-GM pickup coils are junk, but I don't know how true that is.

Jul 11, 2011 | 09:08 AM

#22

AGENT 86

Team Owner

Joined: Jan 2003

Posts: 20,316

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From: Summerland B.C. Canada

Quote:

Originally Posted by Jim Hannon

Was wondering about injectors? Had a fuel pressure guage on and when I turn key on I get an immediate 42psi and then it drops 10psi after pump goes off to 30psi in less than a second. It zeros out within 5 to 10 seconds. Is this normal or do I have some leaking injectors? If so could this be the cause of the erratic spark showing up on the timing light because of a weak spark from flooding and the motor to miss?

Could be a leaky pulsator above fuel pump. My fuel pressure had similar readings at one time and that was where my loss was. I replaced it with a piece of injection hose and 2 clamps.

Do some pinch tests to narrow down the area of loss.

http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf

Jul 12, 2011 | 12:53 AM

#23

Jim Hannon

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From: Newton Ks

Quote:

Originally Posted by AGENT 86

Tried the pinch test like you suggested. I did the first step it said to

IGNITION "OFF" FOR 10 SECONDS.
IGNITION "ON"
BLOCK FUEL PRESSURE
LINE BY PINCHING FLEX
HOSE, PRESSURE
SHOULD HOLD.

And it did hold. It said to CHECK:
• LEAKING PUMP COUPLING
HOSE OR PULSATOR.
• FAULTY IN-TANK PUMP.

We are going to try the Pulsator fix like you did. My other question is during the pinch test the fuel pressure held a 38psi is that somthing that I should be concerned about? The reason I ask is the FSM states that fuel pressure should be, "WITH PUMP RUNNING SHOULD BE 280-325 kPa(40.5-47 psi)" I also have a Haynes manual that says 34psi to
39psi. Which one would you say is correct? Im was not for sure because of revisions. Thanks alot for all your help. By the way what exactly does the pulsator do?

Last edited by Jim Hannon; Jul 12, 2011 at 01:50 AM. Reason: add info(I cant spell)

Jul 12, 2011 | 01:44 AM

#24

Jim Hannon

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From: Newton Ks

New info on erratic spark problem. Decided to check spark with spark tester and noticed that at .035 the spark didnt seem to be very powerful. I decided to adjust the gap more on the tester to check the spark color and it made the plug wires short out all over the place. When I checked them before in the dark I saw nothing. When wires are hooked to the plug as normal no arcing is noticed. Anyone have this problem before? The wires were purchased from a friend and was supposed to be NEW. Getting new wires tomorrow. Have any ideas why this would only happen when the spark tester is on the wires and set at a bigger gap?

Jul 12, 2011 | 03:10 AM

#25

Cliff Harris

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Joined: Apr 2002

Posts: 10,036

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From: Anaheim CA

If you replace the pulsator with a length of hose make sure it's SUBMERSIBLE. Most fuel hose expects the fuel to be on the inside, not the outside. You don't want your hose dissolving in the fuel tank. This is especially true if your fuel has ethanol in it.

This is the Right Stuff:

http://www.amazon.com/Gates-Rubber-C...0454289&sr=8-2

Prepare for sticker shock: it's about $25 for ONE FOOT.

Last edited by Cliff Harris; Jul 12, 2011 at 03:12 AM. Reason: Added price.

Jul 12, 2011 | 08:58 AM

#26

AGENT 86

Team Owner

Joined: Jan 2003

Posts: 20,316

Likes: 246

From: Summerland B.C. Canada

Quote:

Originally Posted by Jim Hannon

I also have a Haynes manual that says 34psi to
39psi. Which one would you say is correct? Im was not for sure because of revisions. Thanks alot for all your help. By the way what exactly does the pulsator do?

I wouldn't trust anything from a Haynes manual.

The pulsator's purpose is similar to a water hammer arrestor. The opening and closing of injectors, causes a shock wave in the line. I haven't noticed any difference without it.

Jul 19, 2011 | 09:53 PM

#27

Jim Hannon

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From: Newton Ks

New update got rid of miss and rich exhaust smell. Threw away timing light put in new injectors from injector connection timed by ear, now runs great. Noticed that the O/2 sensor are gone. How is the car running without pulling any codes?