Call Rich at Abel Chevrolet!...

Abel Chevrolet knows Corvettes and are Highly Recommended!!!...
http://www.abelgm.com/

 

got to drive in an 85 vette today, that a guy is selling (or trying to).
he's a mechanic, bought this car a year ago, from family of a guy who passed away. said he's been working on it to make it his personal car (well
actually he's turning it into a race car).
he put a pretty heavy duty engine in it-and whew, it is fast!
i asked him what he did w/ the original engine-he said he tossed it, said it
was "junk".
i sort of laughed when hearing it.
but riding in his car vs my experience in the 2 90s vettes i've driven,
his blew them out of the water. car was crazy fast. i was actually scared
a bit at how much it could accelerate!

 

much thanks to you all. I will get with a friend of mine who is a good Ford mechanic and electrical trouble shooter next weekend. We'll start and stop it until it fails and then do our checks. I will let you all know what we find and send out an SOS if we need some help. I'm feeling much better now. I want to keep it stock, if I can, for sure! I love the car! When I get this resolved I will include some photos.........

 

Please continue to post on this thread! We know it's a PIA to go through this but the information may save someone else the misery you're encountering. It's also obvious that there are very knowledgeable people anxious to help you solve this problem.

 

GL don't give up on the fuel injection..You will thank us later.

 

Spartan bro....i admit that i am noob to these cars but so far, there has not been anything that has stumped me ony because of the boys on this forum. you can do this!! If this is your daily driver, then perhaps the best thing is to sell it off and get a reliable dd. If its not our daily driver...like others have said...grab a beer and can you make an organized list of things you have checked, replaced, and the values of certain things such as fuel pressure with key on, bleedoff time, fuel pressure while cranking, fuel pressure while idling, fuel pressure while cruising and when you stomp on it.

Guys can you help us out here, like lets get a basic list going:

IAC_______ (checked/replaced?)
FPR ______ (checked/replaced?)
Fuel pressure values, key on ___, bleed off time ___, cranking ____, etc.
Vac pressure _____
Oil pressure at idle ______
Oil pressure crusing ______
Idle oil temps ____
cruising oil temps _____
coolant temp sensor ______ (checked/replaced?)
coolant temp at idle _______
coolant temp at cruising ______
Checked all grounds on the car? ____
Injector voltage? 1._____2._____3._____4._____5._____6.___ __7._____8._____
Injector leakdown test? ____
Compression check? 1._____2._____3._____4._____5._____6.___ __7._____8._____


(guys I am flying blind here just like Spartan...what else would you want him to check? can you add to this list? Is there already a list like this? a list of things to track when we have a wtf condition nobody can figure out?)


There may already be a list like this. The thing is that the shop manual may miss things (like the shape and removal procedure of the friggin bolt under the ac compressor) and the only place you will find that info is on this thread.

to me this sounds like a ground issue, or a relay that is failing and sometimes allows power to get through and other times not depending on stuff like humidity and temperature.

Spartan if you make the effort to do your own evaluation of what the facts are, and contain them in a coherent "list" like my example above, I have 100% faith in the boys on this thread. They are amazing and they will help you get it sorted out before any mechanic will.

If it is your DD, then I agree with the boys here....take it to a specialized C4 vette mechanic. But if its not your DD, lean on this thread...and they will respond.

 

And therein lies your problem, i.e. incompetant (on your car) mechanics.

These TPI cars are not all that complex.
Firs off jumper the ALDL pins A&B to pull any trouble codes.
If it cranks verify:
- fuel pressure (gauge)
- injector firing (diagnostic light)
- spark firing (timing light)
- ignition timing (verified when it does run)
If if does not crank check:
- ignition switch
- tranny safety switches
- VATS

Hope you can find a competant mechanic for your Vette.

 

spartangreek, for a few dollars you could call Gordon Killebrew. He has a web site and offers schooling for owners to learn about their C4's. His experience was obtained working at the Corvette Plant in Bowling Green. At one time years ago a C4 Corvette owner could call the Corvette Plant and and talk to Gordon about their problems with their C4. He does seminars at Corvette shows about the C4 Covettes and helps the C4 owners. To bad you don't live close enough to take your Corvette to his school for a week-end.

 

[QUOTE=65Z01;1588190930]And therein lies your problem, i.e. incompetant (on your car) mechanics.

These TPI cars are not all that complex.
Firs off jumper the ALDL pins A&B to pull any trouble codes.
If it cranks verify:
- fuel pressure (gauge)
- injector firing (diagnostic light)
- spark firing (timing light)
- ignition timing (verified when it does run)
If if does not crank check:
- ignition switch
- tranny safety switches
- VATS
Hope you can find athanks to all! I am going to attempt to get it fixed this weekend with a friend of mine who is a good mechanic. I have a 1988 corvette GM service manual and it has several good pages on troubleshooting "cranks but won't start" including wiring diagrams. We'll give her a good shot and I will get back to you!
competant mechanic for your Vette.

 

Look fwd to hearing success!



[QUOTE=spartangreek;1588198387]

 

Right on. These are the checks and in the right order.

 

Sounds like to me all your and the PO's "mechanics" have been throwing parts at it in the hopes of curing your issue and failing miserably. You have gotten sound advice here, start with the basics. I definitely would eliminate the VATS to mark that off the list. I would find all the ground points and clean them up. They can cause a lot of weird problems. I would test your ignition coil and pick up coil in the distributor. Very simple with a ohmmeter. I would check the oil pressure sensor IIRC it will tell the fuel pump to run once it sees proper pressure or shut the pump down if no pressure. Get a fuel pressure gauge and when it wont crank, check at the fuel rail. It should still have pressure even if the car is not running.

There are a few more suggestions. Get out your FSM and read the diagnostic trees and follow them down. They have solved my issues morte than once.

Good luck and keep reporting back as to what you find. I am sure the solution will be a lot less than $2K.

 

Did some diagnostics today adn here is what we found, without the use of a scan tool which we do not have:
1. fuel pressure was very good, held steady after cranking. We taped the guage to windshield and drove around and it was at 47 psi.
2. Checked spark and there was no fire.
3. disconnected 4 terminal EST connector and checked for spark. There was spark! Service manual says to replace coil but the coil was just replaced 2 weeks ago with an Accel.
4. used noid light to check injectors. They were not pulsing.
5. Checked wiring and grond connections in distributor/coil and all "ok"
noticed a code 12 refference in manual that indicates a possible faulty ECM or a short in voltage circuits 467 & 468. Had no scanner so will have to get a scan tool to perform further tests.
the mechanic seems to think since we eliminated Fuel and spark that it is the ignition and thinks it is down to the ECM or the injector wiring harness being at fault. I had the dealer replace the ECM 3-4 weeks ago so I will take it back to them since it is under warranty and have them check it out again.
also found the water pump leakinf and serpentine belt cracked. will replace that along with hoses shortly
spartangreek

 

i agree with all DinoBob advices. stay calm,drink the beer,start at the basics.

fuel pressure good and steady at 40psi (you need a fuel pressure gauge 30 $)
spark, an heavy blue spark.
injectors ohmed /pulses (you need a noid light to test for pulse)

1 check fuel pump priming the rail,it runs for 2 seconds with key on.pump ok
2 again pump runs but you NEED good pressure ,pump may run but not build up pressure.
3 pressure test.connect a fuel gauge to the rail valve,wrap a towel around the valve to prevent gas spilling.turn the key and check fuel pressure with vacuum disconnected at fuel pressure regulator.you nedd STEADY 40 psi.ok you have steady pressure
4 you have good pressure but are the injectors pulsing?no pulses... not gas into combustion chambers....
5) noid test ,using a noid light connected to injectors connectors, test for pulses.if the light is blinking then you have reference pulses from ECM.the ECM is good.

Now on the spark side...
12 volts to distributor...ok 12 volt
have spark plugs good blue spark? no spark ... go into the distributor an check the ignition module.
spark is ok good and blue (try it in a dark garage)

TPS sticking or binding WOT...if TPS sensor in your TB is sticking in high position the ECM enter in the Clear flood mode and fuel is turned off which cause a no start condition...

 

sorry i posted after you... i suspect the ignition module inside the distributor...

 

Replaced it last week!

 

How could you drive around if there was no fire?

That 4 pin connector joins the distributor to the ECM. When it is unplugged the ignition module supplies the spark and a crude timing curve.

The ECM pulses the injectors. It uses pulses from the distributor to synchronize the pulsing of the injectors to the rotation of the engine. That 4 pin connector has to be connected for this to happen. Note that if the VATS signal to the ECM is missing then the ECM will not pulse the injectors.

Code 12 means no reference pulses from the distributor. The engine has to be rotating to produce those pulses. Error code 12 is normal if the ignition is on but the engine is not rotating. The ignition module must be working and the pickup coil inside the distributor has to be working.

You can extract the error codes from your car using the "paperclip method":

http://forums.corvetteforum.com/1574918379-post18.html
http://corvettephotographs.com/c4vettes/codes.htm

What they mean:

http://forums.corvetteforum.com/1576116036-post35.html

 

as cliff said, if your vats is f'd, ecu wont send signal to injector to pulse.

vats is vehicle anti theft system.

the strange part is i thought vats wouldnt allow cranking and it sounds like u r cranking.

sounds like u r narrowing in on it. im a noob like urself and im here to root you on!! VikingTrad3r

 

i feel you are almost there...you can solve this problem...it's a simply electrical issue...probably no parts have to be changed.And you were ready to carb this car...

 

How could I drive it if there was no fire? If you read my first post I stated I have an intermittent starting problem. It has a ghost that allows it to start or not start anytime it pleases! I started it until it failed and then we began our troubleshooting, first check was the fuel pressure. We hooked up the hose/gauge and cranked and the engine wouldn't start. The fuel press. was over 40 psi and held for several minutes. When I went to crank it up again it started and so we drove it while monitoring the fuel pressure. I might add that that was the first time it started so quickly after failing. I have to wait several hours most if the time. Once we got it to fail again it would not start through the remainder of our testing and I had to let it coast down the driveway when we were finished. I also can say that I know it has to get up over 200 degrees before it won't start. I thought it would do it when it was cold too but I was wrong. I flooded it once when it was cold and that mislead me. I now know the proper way to start them....no pedal! So far I have eliminated the coil, ignition module, fuel, and spark. It has to be ignition though so I'm thinking that leaves only the ECM or the injector wiring harness. the ECM was diagnosed bad and replaced by a dealership right after I bought it. It is a remanufactured unit and is under warranty. The service manager said they have had problems with them on other vehicles and had to replace them multiple times. I will take it back to them again. Last time I did they said they couldn't get it to fail but I don't think they tried very hard. I will lean on them now. As for the vats it is my understanding that when it is bad the engine won't turn over. Mine does.
thanks for all of the input!