need help diagnosing
Thread Starter
Burning Brakes
Joined: Jan 2007
Posts: 853
Likes: 0
From: Slinger WI
need help diagnosing
greetings i have a t the moment a fairly stock 1986 corvette, i am experiencing a problem with. on cold start ups for the day, this car is a beast to start! i could crank steady, and the car wont even pop. i just crank for 1 second and stop, wait a couple of seconds and repeat. usually around the 8th time, it starts popping over, than a couple more times like this, and than it starts, and runs flawlessly rest of day. fuel pressure fine, complete tune-up, was no help. is this a suspect for leaking injectors? how do i test for this? it does seem, when car sits overnight, this problem occurs only. also seems that the warmer it gets outside, the tougher it is to start. please some input. i do have a fsm, among other testers. please help me start correcting. THanks for your time.
Last edited by lltrevino; Jun 6, 2007 at 05:01 PM.
Safety Car
Joined: Sep 2003
Posts: 3,598
Likes: 23
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
greetings i have a t the moment a fairly stock 1986 corvette, i am experiencing a problem with. on cold start ups for the day, this car is a beast to start! i could crank steady, and the car wont even pop. i just crank for 1 second and stop, wait a couple of seconds and repeat. usually around the 8th time, it starts popping over, than a couple more times like this, and than it starts, and runs flawlessly rest of day. fuel pressure fine, complete tune-up, was no help. is this a suspect for leaking injectors? how do i test for this? it does seem, when car sits overnight, this problem occurs only. also seems that the warmer it gets outside, the tougher it is to start. please some input. i do have a fsm, among other testers. please help me start correcting. THanks for your time.
Thread Starter
Burning Brakes
Joined: Jan 2007
Posts: 853
Likes: 0
From: Slinger WI
What do you mean by "fuel pressure fine"? Did you put a pressure gauge on it? What did it read while the engine was running? What did it read when you shut the engine off? If it dropped down to 0 quickly, you might have leaky injectors. There is a test procedure in the FSM for that.
Last edited by lltrevino; Jun 7, 2007 at 10:54 AM.
Safety Car
Joined: Sep 2003
Posts: 3,598
Likes: 23
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
A minute is relatively quick. Did it go down to 0? You'll get varying responses, but most would be in the 5 minute to 30 minute range of holding pressure. Keep the gauge on for at least 30 minutes or until pressure is 0.
Team Owner
Joined: Jan 2003
Posts: 20,254
Likes: 221
From: Summerland B.C. Canada
Try planting the gas pedal to the floor during cranking. This will put the ECM into "Flood Mode" and it will cut back the amount of fuel delivered. If it starts quicker, it may be a sign that you have leaking injector(s).
The FSM has some good info on tracking down fuel delivery problems.
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
The FSM has some good info on tracking down fuel delivery problems.
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
Thread Starter
Burning Brakes
Joined: Jan 2007
Posts: 853
Likes: 0
From: Slinger WI
i did a thorough fuel pressure today on a cold start. i cycled key on, went to 35#. started car up, went to 39#. shut car off, went immediately to 15# after shutting car, and turning key off. after 1 minute, down to 10#. around 15 minutes, read 0 #. i dont think these numbers are oem, so are my injectors leaking down? is this why cold morning starts are tough?
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Safety Car
Joined: Jul 2004
Posts: 3,834
Likes: 30
i did a thorough fuel pressure today on a cold start. i cycled key on, went to 35#. started car up, went to 39#. shut car off, went immediately to 15# after shutting car, and turning key off. after 1 minute, down to 10#. around 15 minutes, read 0 #. i dont think these numbers are oem, so are my injectors leaking down? is this why cold morning starts are tough?
thinks so or may be one of the check valves...
Burning Brakes
Joined: Aug 2005
Posts: 1,050
Likes: 0
From: Portsmouth VA
greetings i have a t the moment a fairly stock 1986 corvette, i am experiencing a problem with. on cold start ups for the day, this car is a beast to start! i could crank steady, and the car wont even pop. i just crank for 1 second and stop, wait a couple of seconds and repeat. usually around the 8th time, it starts popping over, than a couple more times like this, and than it starts, and runs flawlessly rest of day. fuel pressure fine, complete tune-up, was no help. is this a suspect for leaking injectors? how do i test for this? it does seem, when car sits overnight, this problem occurs only. also seems that the warmer it gets outside, the tougher it is to start. please some input. i do have a fsm, among other testers. please help me start correcting. THanks for your time.
Thread Starter
Burning Brakes
Joined: Jan 2007
Posts: 853
Likes: 0
From: Slinger WI
1 second cranks work the best. if i sit and crank steadily, the engine wont do a thing except spin. no popping or kicking. if i will crank for 1 second at a time, it will at least start kicking over around the 8th try.