1994 Corvette C4 Major Issues
Team Owner
Joined: Sep 2003
Posts: 25,389
Likes: 2,741
I believe the OP has just returned and the missing posts might sort OR help!! I don't believe the OP likely ever saw the
"NO CRANK or CRANKS NO START"
Last edited by WVZR-1; Mar 30, 2016 at 02:20 PM.
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
Fuel pressure should be in the low 40's sitting. If I understand what your saying I would change the fuel filter and clean and test the battery and the connections behind it and the cables as well as both ends. Battery needs to be removed to see. What did you use to replace the pulsater?
look on youtube you can get the codes with a paperclip I thought I put this info in before. But was removed with my answer to the fussing.
look on youtube you can get the codes with a paperclip I thought I put this info in before. But was removed with my answer to the fussing.
Last edited by antfarmer2; Mar 30, 2016 at 03:03 PM.
Safety Car
Joined: Sep 2010
Posts: 3,752
Likes: 190
From: Indiana PA
I've actually bought an obdII scanner and went through all the codes there aren't any that concern problems with the engine odly enough. I'm really starting to think it could be the optispark I've heard if those get wet its bad news. I'm really at a loss of what the problem could be for this car... For instance I started the car today and it ran fine in the morning. Then towards the afternoon it died while I was driving again and I just coasted to the side of the street. I also think it could be a bad injector, and it is also worth noting for some reason the cars fuel pressure runs at about 33 Psi when the car is on even after I installed the new regulator and pump. Anyways thought those could be some useful hints.
You NEED to determine when this happens what you are missing.
I suspect you find that cause you will also fix the vehicle dying at random times as well.
33psi is perfect. Watch this carefully.
Do you have fuel pressure during the crank/no start? Yes or No.
Using a spark tester, do you have spark during this crank/no start time? Yes or No.
Watch this for more info. The basics apply everything.
You NEED to do some testing. Not some guessing.
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
Ok lets start simple. Based on what you said, you have a crank, no start at times.
You NEED to determine when this happens what you are missing.
I suspect you find that cause you will also fix the vehicle dying at random times as well.
33psi is perfect. Watch this carefully.
Do you have fuel pressure during the crank/no start? Yes or No.
Using a spark tester, do you have spark during this crank/no start time? Yes or No.
Watch this for more info. The basics apply everything.
You NEED to do some testing. Not some guessing.
You NEED to determine when this happens what you are missing.
I suspect you find that cause you will also fix the vehicle dying at random times as well.
33psi is perfect. Watch this carefully.
Do you have fuel pressure during the crank/no start? Yes or No.
Using a spark tester, do you have spark during this crank/no start time? Yes or No.
Watch this for more info. The basics apply everything.
You NEED to do some testing. Not some guessing.
And runs about the same with some fluctuation.
Last edited by antfarmer2; Mar 30, 2016 at 07:44 PM.
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
Check for codes, spark and fuel pressure and let us know. The way I read your post it would not even crank that meaning the starter was not turning over. But could be taken that it was cranking and not starting what is it doing?
Last edited by antfarmer2; Mar 30, 2016 at 08:04 PM.
Safety Car
Joined: Sep 2010
Posts: 3,752
Likes: 190
From: Indiana PA
The way I read that, he is saying the car is RUNNING. Interpreted that way I fail to see what is wrong with my post.
He said the car was ON, not the Key was ON. Those mean two entirely different things to me.
If you actually watch my video I make it pretty clear what pressures should be at all key positions and engine on and off. 5 pressures should be listed if you do the test right, but what do I know.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
I drove my car for 8 years everyday going to work in rain or sunshine. Never affected the opti nor did my leaking water pump. Having said this, driving in the rain is not the kiss of death.
Although dropping the opti low resolution pulse drive can flat out stop the engine of make for hard starting, you have not really stated any drivability problems or symptoms that are characteristic to a bad opti. Personally I would not have it on the top of my list yet. If and when you actually pull the codes, this might shed light on a possible opti problem from the optical sensors.
NOTE: Every time you disconnect the battery, you clear the codes in the PCM.
It's just that a lot of your symptoms first makes me think of a bad ICM which is easy to change and not too costly. If it actually fails when you can work on it (like at home), I would check for spark as already indicated.
At this time I just don’t think there is a fuel problem even the filter which usually affects higher speed driving first and not necessary starting or lower speed driving. You've replaced most of the fuel related parts already. IMO.
Last edited by pcolt94; Mar 31, 2016 at 10:10 AM.
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Thread Starter
Intermediate
Joined: Mar 2016
Posts: 47
Likes: 0
From: Rancho Santa Margarita California
Thank you all
I'm really sorry if my post was confusing. Forget all that I have said before.
Problems:
- Car shuts of "dies" while driving or idleing spontaneously
- Fuel pressure is low
- Car only sometimes starts
- Car Backfires and Lurches
As it currently sits:
- The Car cranks but only starts about half of the time
- Fuel pressure runs at about 33 psi
- Lurching and Backfiring occurred at higher speeds today
- The car will die while driving spontaneously
What I Have Done:
- New fuel pump
- New fuel regulator
- Cleaned battery and ground straps
- Sprayed starter fluid into intake (Which did not help to get the car to start)
What I have ordered/am going to order:
- New opti
- New ICM
- New Water Pump
Hope this clears up confusion and can help with ideas. I'm really sorry for making everyone mad/confused.
Problems:
- Car shuts of "dies" while driving or idleing spontaneously
- Fuel pressure is low
- Car only sometimes starts
- Car Backfires and Lurches
As it currently sits:
- The Car cranks but only starts about half of the time
- Fuel pressure runs at about 33 psi
- Lurching and Backfiring occurred at higher speeds today
- The car will die while driving spontaneously
What I Have Done:
- New fuel pump
- New fuel regulator
- Cleaned battery and ground straps
- Sprayed starter fluid into intake (Which did not help to get the car to start)
What I have ordered/am going to order:
- New opti
- New ICM
- New Water Pump
Hope this clears up confusion and can help with ideas. I'm really sorry for making everyone mad/confused.
Last edited by PsarosJake; Mar 31, 2016 at 02:25 AM.
Team Owner
Joined: Sep 2003
Posts: 25,389
Likes: 2,741
A local shop might have a known/thought to be good acquired this way. Is it worth an ask? Maybe.
Last edited by WVZR-1; Mar 31, 2016 at 09:16 AM.
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
I ain't going to get further than this into this BUT if you haven't bought the ICM yet you might consider a test of it at the local AP store. It's not a positive test for sure (lot's of false positives) but it's inexpensive (FREE). Most mention that regardless of the "green light" if it doesn't "get hot" consider it a false positive. In a shop driveabilty situation most frequently it's replaced. (it generally has to be purchased so it's non-returnable to the vendor by the shop) if it didn't fix. If it didn't fix it the shop has a now known/thought to be good ICM for tests later. The customer paid for it.
A local shop might have a known/thought to be good acquired this way. Is it worth an ask? Maybe.
A local shop might have a known/thought to be good acquired this way. Is it worth an ask? Maybe.
Team Owner
Joined: Sep 2003
Posts: 25,389
Likes: 2,741
***Actually there was a VIN specific recall for engine wire harness failure/problem for '94 (94C21) That would have been for very early cars.I have that document.
TSB 41-65-25 is DIS Specific all cars (Diagnostics for driveability)
TSB 87-65-27 Opti-Spark specific and addressed ID etc. (This one is later in '98)
Last edited by WVZR-1; Mar 31, 2016 at 10:38 AM.
Thread Starter
Intermediate
Joined: Mar 2016
Posts: 47
Likes: 0
From: Rancho Santa Margarita California
Burning Brakes
Joined: Nov 2009
Posts: 828
Likes: 103
From: Olney MD
The Optispark...in the garage...with the lead pipe
Glad you got it fixed. I have 2 LT1 C4s, and had to replace the Opti in both of them. So that's the conclusion I jumped to right away. I didnt see this thread in time to weigh in, but like others, i've tried to diagnose and replace other parts (the easier to remove ones) before deciding that the Opti needs to come out.
The second time I did it I got an electric water pump. I'm hopeful that helps to keep the other one safe for a few years. I know that my approach is frowned on by those logical types who advocate testing before acting, but trust me, it's always the OptiSpark!!
Good luck!
The second time I did it I got an electric water pump. I'm hopeful that helps to keep the other one safe for a few years. I know that my approach is frowned on by those logical types who advocate testing before acting, but trust me, it's always the OptiSpark!!
Good luck!