88 Intermittant Starting
Thread Starter
Safety Car
Joined: Jul 2004
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88 Intermittant Starting
Me again,
Have an 88 vette automatic....new plugs, wires, etc, fuel pressure fine, all guts under distributor cap have been replaced, no computer issues, coil, etc....
...The problem is that i have had for years intermittent starting and, for no apparent reason....I can attempt to start the car today and have a no start situation and let the car sit---then, come back a day or so later and it starts right up.....It is not the vats.
....i am aware of the safeguards (re;oil pressure, etc) to prevent damage to engine in event of little or no oil pressure....I also know that the car, apparently governed by the oil pressure sending unit "reading" will allow start at 4lbs(?) of oil pressure.
....So, what i am thinking is that there may be some issue with the sending unit that will cause this to happen...While it appears to be a PITA to replace the sender (remove the distributor) would i be able to short out or jumper the sending unit to eliminate this as a cause?
Have an 88 vette automatic....new plugs, wires, etc, fuel pressure fine, all guts under distributor cap have been replaced, no computer issues, coil, etc....
...The problem is that i have had for years intermittent starting and, for no apparent reason....I can attempt to start the car today and have a no start situation and let the car sit---then, come back a day or so later and it starts right up.....It is not the vats.
....i am aware of the safeguards (re;oil pressure, etc) to prevent damage to engine in event of little or no oil pressure....I also know that the car, apparently governed by the oil pressure sending unit "reading" will allow start at 4lbs(?) of oil pressure.
....So, what i am thinking is that there may be some issue with the sending unit that will cause this to happen...While it appears to be a PITA to replace the sender (remove the distributor) would i be able to short out or jumper the sending unit to eliminate this as a cause?
Racer
Joined: Oct 2006
Posts: 438
Likes: 14
From: Tucson/Santa Paula AZ/CA
2017 C4 of Year Finalist
This is a myth, the connection to the oil pressure switch is only there to provide a redundant source of 12V to the fuel pump in case the fuel pump relay fails. You do NOT need this signal unless you have a failed relay.
Have you used a noid light on your injectors when it won't start? Do you have good fuel pressure at the rail when it fails to start? I assume it cranks but will not run, right?
Mick
Thread Starter
Safety Car
Joined: Jul 2004
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Da,
This is a myth, the connection to the oil pressure switch is only there to provide a redundant source of 12V to the fuel pump in case the fuel pump relay fails.
crap!..i forgot this!
You do NOT need this signal unless you have a failed relay.
no problem.
Have you used a noid light on your injectors when it won't start?
have voltage to the injectors which i believe this car year are batch fired - none-the-less, have voltage, no problem...when cranking, i should have spark to each plug and do not.
I have also checked that i had voltage on the 12vdc wire to the cap while in a no start situation and, have replaced coil with several known good ones.
Do you have good fuel pressure at the rail when it fails to start?
yes, i believe i had stated this...it is not a fuel pressure problem.
I assume it cranks but will not run, right?
as i stated - no spark.....module, and all electronics have been replaced under cap (coil included)..usually as i have done in the past, have removed module under cap and replaced and car would start...then, immediately i would put the old module right back and car starts!...i see no broken, frayed or loose wires...this is the part that is screwing with me!....now remember, i have replace ALL/EVERYTHING below and above the cap!
This is a myth, the connection to the oil pressure switch is only there to provide a redundant source of 12V to the fuel pump in case the fuel pump relay fails.
crap!..i forgot this!
You do NOT need this signal unless you have a failed relay.
no problem.
Have you used a noid light on your injectors when it won't start?
have voltage to the injectors which i believe this car year are batch fired - none-the-less, have voltage, no problem...when cranking, i should have spark to each plug and do not.
I have also checked that i had voltage on the 12vdc wire to the cap while in a no start situation and, have replaced coil with several known good ones.
Do you have good fuel pressure at the rail when it fails to start?
yes, i believe i had stated this...it is not a fuel pressure problem.
I assume it cranks but will not run, right?
as i stated - no spark.....module, and all electronics have been replaced under cap (coil included)..usually as i have done in the past, have removed module under cap and replaced and car would start...then, immediately i would put the old module right back and car starts!...i see no broken, frayed or loose wires...this is the part that is screwing with me!....now remember, i have replace ALL/EVERYTHING below and above the cap!
Last edited by Da Mail Man; May 15, 2013 at 03:55 PM.
Racer
Joined: Oct 2006
Posts: 438
Likes: 14
From: Tucson/Santa Paula AZ/CA
2017 C4 of Year Finalist
Have you used a noid light on your injectors when it won't start?
have voltage to the injectors which i believe this car year are batch fired - none-the-less, have voltage, no problem...when cranking, i should have spark to each plug and do not....now remember, i have replace ALL/EVERYTHING below and above the cap![/B]
...now remember, we can't fix it if you don't answer the questions we ask. No distributor pulses and no spark indicates you have a problem
with the ICM wiring OR the ECM
Mick
Last edited by QZRBLU; May 15, 2013 at 08:15 PM.
Thread Starter
Safety Car
Joined: Jul 2004
Posts: 3,835
Likes: 30
With a noid light or a 12V LED you can determine if the injectors are receiving the ground pulse that activates them.
***what part of this is not the issue did you not understand?..i have no spark coming from the cap to the spark plugs and it is NOT the wires either!
12V should be there on both connector pins(with the ignition ON) until one side is pulsed to ground for that bank.
...now remember, we can't fix it if you don't answer the questions we ask.
**now, i consider this, your response, rather condescending! i have supplied all the information and more...THIS IS NOT AN ISSUE OF VOLTAGE (AS THERE is VOLTAGE) AT THE INJECTORS....It is an issue of no spark at the plugs. now remember, you cannot help here if you cannot understand what i wrote (see, it goes both ways!).
***what part of this is not the issue did you not understand?..i have no spark coming from the cap to the spark plugs and it is NOT the wires either!
12V should be there on both connector pins(with the ignition ON) until one side is pulsed to ground for that bank.
...now remember, we can't fix it if you don't answer the questions we ask.
**now, i consider this, your response, rather condescending! i have supplied all the information and more...THIS IS NOT AN ISSUE OF VOLTAGE (AS THERE is VOLTAGE) AT THE INJECTORS....It is an issue of no spark at the plugs. now remember, you cannot help here if you cannot understand what i wrote (see, it goes both ways!).
Racer
Joined: Oct 2006
Posts: 438
Likes: 14
From: Tucson/Santa Paula AZ/CA
2017 C4 of Year Finalist
without answers I can't help. 12V does NOT fire the injectors, the ground pulse does.
Have fun....IF you have a FSM, start probing the distributor pulses. You need the reference pulses to create a spark AND to fire the injectors.
Last edited by QZRBLU; May 15, 2013 at 08:18 PM.
Thread Starter
Safety Car
Joined: Jul 2004
Posts: 3,835
Likes: 30
Nevermind,
not a bit of a problem here with that since you don't understand the problem with the given facts anyway.
without answers I can't help.
gave you the answers - not my fault you cannot understand them and started going off on tangents.
12V does NOT fire the injectors, the ground pulse does.
i never said that - please refer to my above statement....either way, i have voltage at the injectors and they are firing. for some reason, you cannot acknowledge the fact that there is no spark hitting the plugs WHICH IS THE ISSUE.
Have fun....IF you have a FSM, start probing the distributor pulses.
"not"
not a bit of a problem here with that since you don't understand the problem with the given facts anyway.
without answers I can't help.
gave you the answers - not my fault you cannot understand them and started going off on tangents.
12V does NOT fire the injectors, the ground pulse does.
i never said that - please refer to my above statement....either way, i have voltage at the injectors and they are firing. for some reason, you cannot acknowledge the fact that there is no spark hitting the plugs WHICH IS THE ISSUE.
Have fun....IF you have a FSM, start probing the distributor pulses.
"not"
