Hard Start/No Start Troubleshooting Log

[Robertwav1]

Watching this thread very carefully. What a nightmare! I hope you guys find the problem soon. Whatever it turns out to be will be a learning experience for sure. As far as parts today. I've learned not to take for granted just because they are new that they are good. This drove me bunkers a few times in my life. Ignition modules or anything that connects electrically, look at them with a glass and make sure the plastic mold didn't overspill into the connectors! Bad fuel pump relay connection, maybe a wire that is not connected well because of corrision. Chasing a problem like this sometimes requires rechecking what you already did if you start to run out of ideas. Good luck and please keep posting.

 

[milehigreg]

What Next?

I swapped in a new ECM last night. AC-Delco reman from Rockauto. The car behaves the same. ad Cranks/catches/dies. I must now send in my old,original apparently working ECM for the core charge because I can't send back the new one. I prefer to have the original but I guess it doesn't matter.

I am getting close to running out of ideas here. There are some tests you can do to check the wiring harness from the distributor ignition module. I have noted some physical damage to the connector inside the distributor. Eckler's has the harness for about $70. Anybody know another source?

I still haven't checked the injectors for shorts to ground.

I haven't checked the coolant temperature sensor.

If it isn't one of those things, I think I am down to chasing wires and connectors for shorts.

I could also go back and start checking everything again like Robertway suggests. It shouldn't take nearly as long now that I have practice on each test.

Any other ideas out there? ;help

Even if you don't have any ideas, the encouragement I get from is helpful.

 

[Robertwav1]

Very frustrating indeed! I've been there before with other vehicles. Once found the problem by accident, when the vehicle shut down I left the key on and started messing around with the some ignition harnesses and heard a relay kick in....it was the fuel pump relay cutting out from a bad ignition circuit. Somethin to check. Also, it bothers me that you went really low on fuel and suspect you're fuel pump. Maybe the filter blocked up from the low fuel condition, depends on the amount of junk in tanks bottom. Do you still have fuel pressure when the car shuts down?

 

[vigman]

Greg.. back to square 1

First
Get a test light ( 12 volt pokey kind )
Hook up your fuel gauge

Hopefully the car will start
Tap into the 12 volt RED line to the Distrib.. let the car run

Hopefully the car WILL die ( I'll give it 5 or so minutes )

If you still had 12 volts to the distrib when the car died..that's good

If you lost fuel pressure when the car dies ( and that's MY bet )

I'll bet you have the dreaded fusable link intermittant

So do that test & let me know the outcome

Vig~

 

[milehigreg]

Thanks for the input Vigman. The car cranks fine, catches and then dies within two seconds. So it runs under bypass mode but dies when it tries to switch to EST mode. This switchover occurs when the engine gets to 400 to 600 RPM. This indicates to me that the plug wires, cap and rotor, coil and injectors all function properly. I have good fuel pressure. The fuel pump has been replaced. Fuel pressure remains after the car dies.

The ECM needs to see several things to control the spark and fuel - air flow from the MAF, TPS voltage, fuel enable signal from the VATS, coolant temperature, manifold air temperature, RPM. Initially after start-up it doesn't use all of these things because it's in open loop. It uses some default values until the coolant temp reaches 160 to 180 F and it switches to closed loop.

I have checked the MAF, adjusted the TPS, checked for the proper signal from the VATS, replaced the fuel pump, replaced the ignition module, replaced the ECM, checked the pickup coil.

If I lost 12 volts when the car died, I suppose that might indicate a fusible link issue but does the feed to the red wire change after the engine catches?

Since the fuel pressure remains after the engine dies, would that indicate that the injectors stopped pulsing? The signal to pulse the injectors always comes from the ECM.

Just thinking out loud here. Any comments on my logic?

 

[ejball]

My EPROM showed up last night, installed it, and I continued to have same problem, but I could get mine to run by adding pressure to the EPROM in just the right place, therefore I'm now sure the ECM board has a connection problem somewhere. I now have an ECM on order to be delivered to a local deler at 2 today. What a pain and cost to get parts for a 1988. Does anyone have a good source for salvage parts for the next time I need something. I only have 36,000 miles and have had no major problems before.

 

[ejball]

milehigreg,
Looked back through all of your comments, I did not see any mention of error codes. Can you get the ECM to flash out any error codes. It would be helpful in finding a wiring problem or sensor problem.

 

[milehigreg]

No Codes

No codes have been stored throughout this saga. I suppose I might check again now that I have a new ECM.

There is a place in Illinois called vette2vette. I got a set of transmission cooler lines from them. Good service and reasonable pricing. vette2vette.com

 

[vigman]

Greg

Please do those 2 test's first ( yes again )...

Your logic is sound.. but for 1 small problem.. the car doesn't STAY running.

My understanding is no codes...

Crank, fire & die....

You can buy a NOID light to see if the injectors are still pulsing as the car is dying ( this plugs in place of an injector ).

My theory is.. that something is losing power when heated ( #1 )

#2 Your fuel pump is loosing electrical connection and is only working during CRANK.. not RUN.. but I NEED MORE INFO to do this via remote.

Search my early posts to Bro-Ken.... we went thru a WHOLE breakdown of the fuel system

Vig~

 

[vigman]

Fuel injectors

Yours only has 2 groups of injectors ( Batch fire )

4 on one circut.. 4 on the other

2 control signals 1 ground.. I would be HARD PRESSED to believe that had failed.. sometimes the ground there gets a bit funky... but it wouldn't do that.

Try something... remove the TACH line ( wire ) the the distrib..


Vig~

 

[milehigreg]

THE LATEST

Measured the resistance of each fuel injector coil at the behest of c4c5specialist. # 1 through # 7 all around 15 ohms. # 8? 3 ohms. :eek So the right side fuel injectors won't fire. 3 ohms is close to a short to ground. I have already ordered some Accel injectors and they are on their way. Rated at 23 pounds per hour. Since I will have the plenum and runners and fuel rail out anyway, I am going to replace the EGR valve and the FPR with new AC Delco parts.

Geez, I hope this is it! hnoes

 

[vigman]

I think not

Assume you have 1 bad injector....( which I agree needs to be replaced ).

This shoudln't keep the car from running...It MIGHT keep the 2nd bank from opening up all the way.. and it should have a BAD MISS...

But the car starting.. and dying straight away... Hmmmm think not.. this is a symptom of something else....

Did you try the test of removing the Tach wire from the distrib?

The OTHER question.. is after the car dies.. do you still have spark?
another thought.....

Have you.. disconnected the 9th injector.. there is a cold start injector?

Mine dribbled.. led to over rich conditions on restarts ( after sitting for an 1/2 hr )

Just some thoughts

Vig~!

 

[vigman]

Oh...

I need to check an older post.. there are 2 fuel injector fuses..
BRB

 

[vigman]

Here's the link I wrote to Ken trying to fix a similar problem

This might be useful

http://www.corvetteactioncenter.com/forums/showthread.php?t=7501&highlight=BRO-KEN

Vig~

 

[Black Bart]

I had this problem on my 89 it was the fuel injectors the ECM Has a built in breaker to protect the injector drivers. When it starts and the bad injector puts too much load on the ECM and it shuts down to keep from burning the drivers out.
Solution was replace faulty injector.

 

[Toms007]

I had this problem on my 89 it was the fuel injectors the ECM Has a built in breaker to protect the injector drivers. When it starts and the bad injector puts too much load on the ECM and it shuts down to keep from burning the drivers out.
Solution was replace faulty injector.

Man Greg I hope this fixes your problem, this is getting painful to read.

 

[ecss]

Assume you have 1 bad injector....( which I agree needs to be replaced ).
This shoudln't keep the car from running...It MIGHT keep the 2nd bank from opening up all the way.. and it should have a BAD MISS...

Leave the electrical connector off of injector #8 and see if the engine will run.

Have you.. disconnected the 9th injector.. there is a cold start injector?

The 9th injector was eliminated in 89.

 

[vigman]

Oh.. and new bit of info

I didn't know about that 9th being dropped in 89.. COOL
I LOVE new info like that.


Great Idea about dumping the connection for #8.... that works too.

That would eliminate any over current issues the ECM might have.

I would suspect if the draw was that high.. the fuse for that bank ( INJ #1 or 2 fuse would pop ) It' s only a 7.5 for #1 bank 1-3-5-7 and a 5 for 2-4-6-8

If you put a NOID light on the injectors.. that would also tell you the story of an injector control shutdown..

The Injectors get a pulsed ground from the ECM

Black Pink for Bank #1 Black Light gray for the 2nd bank

This is worth a try BIG TIME and it will give you ALOT of what it is ( or isn't ) info.

Vig~

 

[ejball]

milehigreg, Any solutions yet? Injector? My 1988 is back to reliable. ECM fixed my problem. PROM was not needed, but has the added benefit of having a better idle than the previous performance PROM I had. While I had the whole dash tore out, I trouble shoot the engine light which had been on for several months, found a bad MAF burn off relay - my check engine light had been on for months. I think this will resolve the battery premature failures I have had too. Put over 100 reliable miles on this weekend - nice to have a reliable vette again. It will be interesting to see what your solution is. Now I need to move onto an intermittent Buzz sound in my radio that has been there since I bought the car 12 years ago. Thanks to everyone on this thread - it helped me look in different directions.

 

[milehigreg]

Thanks for the Input

ecss - I will try disconnecting injector # 8 tonight!

eiball - Glad yours is running well again.

Black Bart - Thanks for the info on the ECM internal injector driver protection. I had wondered if the ECM somehow sensed the problem and shut itself down. I understood the shorted injector coil in a parallel resistive circuit but didn't understand why it would fire and then die. If it was just no current to the other three injectors, it shouldn't have fired at all.

Vigman - I checked the fuses because I thought the same thing. Look a little closer at the wiring diagrams. They show different fuse sizes on three different diagrams. Injector 1 is actually a 20 amp fuse and injector 2 is a 10 amp fuse. They are both good.

I spent part of Saturday putting the dash back together. Takes a little creativity! The injectors should arrive by October 1st. I will order a new EGR and FPR today so I can replace them while I have everything apart. Already have my gasket set.

This has been frustrating but hopefully we have it figured out. I have owned the car since December of 2004 and it has been very reliable. I have taken it to Phoenix and back and to the Black Hills of South Dakota and back with no issues. When I am finished, I will have a new fuel pump and strainer, new ignition module, new ECM and new injectors. The worst part part has been going without my Vette. Every time I see someone else in theirs, I get a bad feeling in the pit of my stomach. The best part has been learning so much about the TPI sysytem and the assistance I received from I will report tomorrow on disconnecting injector # 8.