hard starting problem
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Joined: Sep 2003
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From: charlotte nc
hard starting problem
My 86 C4 spins over an excessive number of times before starting most of the time . I have noticed that it is worse after it sits for about an hour after shut down. However if it sits for several days , it fires up normally .
I checked the fuel pressure and it reads 37.5 psig at idle. After shut down , the pressure drops to around 20 psig after 15 minutes. I suspect that I have a leaking injector or two. Problem is which one. Does anyone have any ideas around the best way to check this out?
I checked the fuel pressure and it reads 37.5 psig at idle. After shut down , the pressure drops to around 20 psig after 15 minutes. I suspect that I have a leaking injector or two. Problem is which one. Does anyone have any ideas around the best way to check this out?
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Joined: Feb 2002
Posts: 11,268
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From: Honolulu, HI
Re: hard starting problem (dwestsr)
Take a multitester and pull off your harnesses. Put the leads on and see if any of them are below 12-14 Ohms.
If one is, it's probably leaky.
Also, you can tell if the car is running rich.
Is it harder to start when the car is warm?
If one is, it's probably leaky.
Also, you can tell if the car is running rich.
Is it harder to start when the car is warm?
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Joined: Sep 2003
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From: charlotte nc
Re: hard starting problem (vvv90)
The car seems to run well with normal fuel mileage (16.6 avg combined driving : ~28 mpg at 70) . It starts well when hot if it hasn't sat for too long. Most of the hard start is after a shut down of from 4 to 24 hours. Thanks for the tip on the multi tester, I'll check it out. thanks
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Joined: Feb 2002
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From: Honolulu, HI
Re: hard starting problem (dwestsr)
Here's another cool tip I just heard (thanks Scorp)
Take your fuel rails and injectors out. Put a piece of paper under each bank and turn the key to on to let fuel pressure build up.
Turn the key to off and wait to see which injector leaks onto the paper.
I know that's kind of extreme, but it's easier for an LT-1 :D
[Modified by vvv90, 4:53 PM 9/23/2003]
Take your fuel rails and injectors out. Put a piece of paper under each bank and turn the key to on to let fuel pressure build up.
Turn the key to off and wait to see which injector leaks onto the paper.
I know that's kind of extreme, but it's easier for an LT-1 :D
[Modified by vvv90, 4:53 PM 9/23/2003]
Thread Starter
Pro
Joined: Sep 2003
Posts: 670
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From: charlotte nc
Re: hard starting problem (vvv90)
vvv90, ichecked the resistance of my injector and all were 16.5 to 16.7 ohms.
after that i rechecked my fuel pressure and got these results:
idle pressure 39psig
Immediately after shut down the pressure jumps briefly to about 43psig and falls to 40 in about one second. I thinks this is the fuel regulator reacting to the loss in vaccuum.
in 4 seconds the pressure drops to 30psig
in 4 minutes the pressure drops to 20psig
in 12 minutes the pressure drops to 10psig
the next thing i'm going to try is to warm up the engine, release the fuel pressure, and try a restart. also i plan to do the same thing but wait overnight to see how it starts.
one other clue is that the car seems to start better if i immediately turn it over vs allowing the pump to build pressure first.
any ideas? :cheers:
Started the car after it sat overnight (with fp bled off). Started immendiately. I think my injectors are leaking , even though the resistance is correct.
[Modified by dwestsr, 4:05 AM 9/26/2003]
after that i rechecked my fuel pressure and got these results:
idle pressure 39psig
Immediately after shut down the pressure jumps briefly to about 43psig and falls to 40 in about one second. I thinks this is the fuel regulator reacting to the loss in vaccuum.
in 4 seconds the pressure drops to 30psig
in 4 minutes the pressure drops to 20psig
in 12 minutes the pressure drops to 10psig
the next thing i'm going to try is to warm up the engine, release the fuel pressure, and try a restart. also i plan to do the same thing but wait overnight to see how it starts.
one other clue is that the car seems to start better if i immediately turn it over vs allowing the pump to build pressure first.
any ideas? :cheers:
Started the car after it sat overnight (with fp bled off). Started immendiately. I think my injectors are leaking , even though the resistance is correct.
[Modified by dwestsr, 4:05 AM 9/26/2003]
Race Director
Joined: Feb 2002
Posts: 11,268
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From: Honolulu, HI
Re: hard starting problem (dwestsr)
Everything sounds good to me. I'd check spark now. How long since a tune up? Cap, wires, plugs?
Pull your 7 or 8 cylinder plugs and check 'em.
Just to be sure :thumbs:
[Modified by vvv90, 10:07 AM 9/24/2003]
Pull your 7 or 8 cylinder plugs and check 'em.
Just to be sure :thumbs:
[Modified by vvv90, 10:07 AM 9/24/2003]
