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Old 09-19-2005, 09:13 AM
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1985 Corvette

Hello. I'm Jim, Vickib's husband. I hope that everyone had a great summer. I have a 1985 Corvette with TPI that I purchased. The car hasn't run for 5 years. The engine would not turn over and the previous owner said that the timing chain was out. I pulled the timing chain cover and found that timing chain was fine but the engine would not turn over. I pulled the engine and found that the number 3 cylinder had hydraulic'd, twisted the rod and shoved the piston against the counter balance on the crank. I found the fuel regulator valve was bad and had over fueled that cylinder. I know that it was fuel because there was no rust in the cylinder. When I pulled the fuel rail I got water out of the rail.

I checked the engine and everything was still standard so I replaced the pistons and rings. New timing chain and gears. I did away with the plastic cam gear and replaced with steel. I put the engine back in the car and hooked everything back up the way that it was when I took the engine out. Now the car will not start. It will turn over and back fire through the intake and the exhaust. I have pulled the distributer and static set the timing to 6 degrees before BTC several times and it does not start. I have even disconnected the distributor advance and this has not helped with the timing. It jumps everywhere. We replaced the ignition module. We rechecked all the grounds and replaced the star washers on each of them. We plugged all the vacuum lines...still won't start. There is vacuum because it whistled when we disconnected the vacuum line to the booster. We checked the harmonic balancer and its fine.

I have checked the TPS sensor and it reads okay with the OHM meter. I have checked the MAP sensor and It checks okay with the OHM meter. Is there a possibility that the Knock sensor and the temperature sensor are in the wrong spots? There were two sensors that looked the same and I put them back in the same spots I think. We hooked it up to 3 different computers and got 3 different fault codes.

I can't get it to run long enough to check anything else. When we took the engine apart, the air plenum on the top for the Edlebrock intake manifold had Silicon all under it where the tube attaches to the plenum. I replace all the gaskets on the plenum and I am wandering what to do next.

I am open to suggestions on what to do. I have the old intake from the car and I am thinking about putting that back on.
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Old 09-19-2005, 09:26 AM
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Ok Stupid questions time.
1. Did you drop and drain tank?
2. Is it firing and running but not for long?
3. Are you positive the Dist. is in correct?
4. Have to double and triple checked your plug wires for connection and correct placement?
5. Have you checked to make sure you have spark?
6. Have you checked and made sure you have fuel?
7. Have you put a fuel pressure gauge on to verify pressure?
8. Can you find someone who can either swap or just test the computer?
9. Are you certain the ertia switch is fine?
10. Will other electircal items work?
11. Is the neutral safety connected?
12. Does it have a chip key and if so do you have correct one?
13. Does this computer use the oil pressure as a fuel shutoff? I know some GM's do.


Hope some of this may help. I always prefer to start cheap/easy and work from there. I was a little confused by post not sure if car was firing or not. Also when I saw you list water coming out of fuel rail. I hope you dropped and cleaned the tank, I would also change the fuel pump, filters and flush the lines.
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Old 09-19-2005, 10:19 AM
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sounds to me as if the timing is still off. Remove the power wire and cap, turn the engine over until the rotor is pointing at number 1 plug wire, pull the distributor and reset the spark timing, make sure it`s on the compression stroke at TDC, then drop the distributor back in, this way the oil pump shaft is already in alignment and the timing is dead on, when you drop it back in it`ll seat and be in time, when did the other way of letting the engine turn over until it drops back on the oil pump shaft it knocks the timing off since there`s about 1/4 turn from unseated to seated position. Are you certain you have the firing order correct? it`s easy to get it wrong on 5 and 7, double check them all and make sure there right. The knock sensor mounts to the very bottom of the block, in the center, right next to the oil pan rail. I would also check and make sure the balancer hasn`t spun, factory balancers are famous for this and could be giving you a false reading, you can use a skinny screw driver through the spark plug hole to make sure it`s at top dead center when the timing tab and balancer says it is.
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Old 09-19-2005, 10:48 AM
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Ok Stupid questions time.
1. Did you drop and drain tank? Yes. Tank was drained and new fuel put in. Fuel pump was pressurized and lines flushed. Added heat just to be sure. Replaced fuel filter.
2. Is it firing and running but not for long? Yes. It is firing but will not run for long. Backfires through the intake and the exhaust. Valves have been readjusted.
3. Are you positive the Dist. is in correct? Yes. have checked and rechecked several times. Remove dist and put screw drive in number 1 and watched to go to TDC. Yes it was on the compression stroke.
4. Have to double and triple checked your plug wires for connection and correct placement? Yes. Have checked plug wire several times. Have done OHM test on all plug wires and they are all reading about the same.
5. Have you checked to make sure you have spark? Yes. I am getting spark on all cylinders.
6. Have you checked and made sure you have fuel? Yes. I put 10 gals of fresh fuel in tank.
7. Have you put a fuel pressure gauge on to verify pressure? Have verified fuel pressure that is how we found out the old fuel regulator was bad.
8. Can you find someone who can either swap or just test the computer? Not sure about this one. I may have to find a salvage yard to get a new computer. I don't know if the dealership will test it or not.
9. Are you certain the ertia switch is fine? Ertia switch??????? Don't know what that is or where it is at.
10. Will other electircal items work? yes... Except for the radio.
11. Is the neutral safety connected? Yes it is.
12. Does it have a chip key and if so do you have correct one? No.. It does not have a chip key.
13. Does this computer use the oil pressure as a fuel shutoff? I know some GM's do. That I don't know. How do I find out?

This is my first post reply so if I screwed it up, please let me know.


Hope some of this may help. I always prefer to start cheap/easy and work from there. I was a little confused by post not sure if car was firing or not. Also when I saw you list water coming out of fuel rail. I hope you dropped and cleaned the tank, I would also change the fuel pump, filters and flush the lines.
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Old 09-19-2005, 10:53 AM
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Firing order has been checked several times. 18436572. When I pulled the engine the wires on the distributor were 13572468. There are two sensors that look alike. One is suppose to be a knock sensor and I am not sure what the other is. I think it is a temp sensor for the electric fan.
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Old 09-19-2005, 11:06 AM
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First, make sure the power/burnoff relay is connected correctly. Its a large rectangular box and it should be near where the computer is. 85 is the only year that used this as in 86 they switched to two regular style 5 prong relays. This gives/regulates power to the MAF sensor. 85 did not have a map sensor. No TPI had one until 90 when they switched to a speed density setup.

These computers do have provisions for an oil pressure shutoff. It should be wired (along with the guage) to the OP sensor in the back of the block (near the back of the manifold). The knock sensor should be on the passenger side of the block down near the starter.

Also verify that your fuel pump relay is continuing to power the fuel pump when cranking. Many times they will go bad and only allow the prime function to happen. Which will allow the engine to run for a second or two.

You need to also set your IAC at wide open. Jumper the A and B connector on the Diagnostic plug and you should hear a little winding. After about 30 seconds, unplug the IAC (its below the TPS). Take the jumper out of the Diagnostic plug. This will allow the IAC to open all the way and let more idle air in.

Also make sure you have the injector clips on the right side. Its a batch fire system, meaning there are injector connectors that are supposed to be either on the passenger, or driver side accordingly.

Hope this gives you some ideas. Feel free to follow up/ask any more questions.
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Old 09-19-2005, 11:11 AM
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Check your distributor rotation vs. the firing order. you may have the right firing order, but opposite rotation of the distributor. check by cranking engine and watching distributor travel.
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Old 09-19-2005, 02:16 PM
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Still sounds like a timing/igintion problem to me. I did have a new cap go bad on me was crossfiring, but that was the only one I've ever heard of or seen.
Good to know you did the tank already. Inertia switch (sorry) is what shuts off the fuel pump in an accident. I've seen several go bad on Fox body mustangs. I've even seen them allow the car to run for brief periods and then trip and seen stereo's trip them before. But from your description I doubt that is your problem.
Another poster did mention your car has an oil pressure safety. I beleive they are towards the back of the motor (at least on the IROC they were) if it is getting a faulty reading or not hooked up it would shut it down.
Even purchasing a new computer may not be helpful there really is no way to be sure it was working in the other car. That's one reason why I like to find someone with a running one and just borrow/swap to see if it helps. heck put yours in their car.
Hope you get it sorted soon.
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Old 09-19-2005, 06:42 PM
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Without a scanner, its very hard to tell what is going on. I have had problems with similar symptoms and each time it was something different. You just need to keep narrowing it down. Check what I said earlier and let us know. My best friend has an 85 Corvette that we deal with all the time. My 66 has an 86 Corvette FI setup (computer and all) and I know these systems pretty much in and out.
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Old 09-19-2005, 08:08 PM
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timing

Doc here,

Verify your static timing. Crank until the marks line up, top dead center, pull the cap and check that the rotor is pointing to #1 plug tower. Now verify both valves are closed.

I'm thinking since you were working on the cam, you may have a timing problem, either cam or dizzy..most likely, 180 out on the dizzy. However, if you cant get #1 TDC, marks up, AND both valves closed you may be off on the cam..

Check that first.

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Old 09-23-2005, 07:31 AM
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85 Corvette

Hi everyone! Vicki here... Just wanted to THANK all of you for some very good advice and lots of things for us to check. unfortunately, Jim was admitted to the hospital on Wednesday and it doesn't look like they are going to let him go anytime soon. It's either his lumbar spine or his hip...still don't know which...at any rate, he can't walk . (Too much time bending over a car that sits 6 inches off the ground?) So please don't think that we're ingoring you or have turned our backs on some really great people. All of you rock! (Big hug to all of you!)

Hope you all have a wonderful weekend!
Vicki
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Old 11-25-2005, 05:48 PM
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Thanks for everyones help

Hello.. This is Jim, Vicki B husband. I am finally back on my feet and have had time to work on the 85 vette. I found that the timing was off one tooth on the cam and crank gear. I also found that the Dist Cap was what they call a show cap. Which I didn't know was on the car. Now I am having trouble starting the car when it is cold. I have not been able to locate the chock or any cold starting stuff on the car. The car has and Eldabrock intake and air horn. What should I do to correct this. Also the fuel regulator is set at 47 lbs. The car requires a 37 lbs regulator but I have not been able to find on. Is there any way that I can adjust the one I have to get it down to 37lbs??? Any assistance would be more than helpful.
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Old 11-26-2005, 02:00 PM
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Check to see if your pressure regulator is adjustable. It is in the fuel rail under the back of the upper plenum. If its adjustable there will be a screw in the top of it that you can turn to the left and right to adjust pressure (turning to the left relieves pressure, and to the right adds pressure). If its not adjustable, you might look into getting an adjustable one.

The cold start switch is in the front of the lower manifold to the left of the coolant temp sensor. The cold start injector is on the drivers bank between the first set of runners and the second set. Make sure these things are plugged in.

Is the car running correctly otherwise?

Is your base timing set at 6 degrees?

Glad to hear your doing better.
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Old 12-28-2005, 08:10 PM
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1985 Corvette

Thanks to everyone for all your help... What I found. The timing was off one tooth between the crank and the cam. Not sure how I did that. Also the fuel regulator was putting out 47 psi and factor is 37 so I got an adjustable regulator. The Dist cap was what they call a show cap. All one side in order 1357 then 2468. The knock sensor wire and the water temp fan switch wires were switched. Two vacuum lines were ran wrong. Other than that the car purrs like a kitten. I hope to take it on its maiden voyage on Thursday.
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