Hard Start/No Start Troubleshooting Log

[milehigreg]

Eureka!!!

Hi all. I am in Phoenix for my baseball tournament. But I had to post to say that I got everything back together Saturday morning before my flight left. Fired her up and she runs and idles! :Twist Wasn't able to drive her but let her idle in the garage and get up to temp. I am as relieved as I am happy and satisfied. Nice to know she awaits my return on Saturday. I love to play baseball but I can't wait to get back on the road with my Vette!

I will post an executive summary of this thread and close it out. Thanks to all for your suggestions and encouragement!

 

[Black Bart]

Anytime you have a problem with engine stalling or idling rough the first thing to do is remove the wires from the injectors and using an ohm meter check across the two pins.
This is much better than just throwing money at it until you get it running again.

 

[Kindaslow]

Hi guys,

I am new to the forum, so please bear with me if I ask a stupid question. My 1984 Vette is also showing classic start-sputter-die symptoms. Because it is a Cross-Fire, I can watch the fuel spray die off while trying to start the thing (this might be the only advantage of a Cross-Fire.) It runs for a few seconds with robust spray patterns, but then the patterns change, and fuel seems to dribble out then die. When supplemented with carb spray, the motor still runs. I know the oil pressure sensor circuit is tied into a fuel pump shutoff, and it also is acting wierdly. With the motor off, but the key turned to the first click, I see that the ECM registers an increase in oil pressure up to 80 PSI with the motor off! What gives??

The fuel pump seems silent, though I hear the solenoid click. There is no whirring. There also seems to be no voltage to the pump when the key is in the first click position.

I have owned this car for 11 years, and have had to fix a good many components so far, but this is the first real Cross-Fire issue I have had. The vehicle was allowed to sit for about 3.5 years, yet ran flawlessly when I tried starting it two months ago. With new fuel, I started having troubles.

Is anybody else thinking that it might be the ECM and/or oil pressure sensor?

Thanks in advance!

 

[Corvette Emma]

Wow, this was a great Thread, I have had trouble with my 89 and just could not figure it out. I didn't want to take it to a shop because it didn't do it all the time.I replaced the fuel filter which seemed to help but it had just gone away for a little while then came back. It just so happens that my car broke down today (6-29-08) and I had to have it towed back to my house. I logged onto CAC to try and get help and found this great thread. I immediatly went out to my car to check the injectors.The following are my resistance readings:
Starting at the front of the engine on the passenger side:
15.8 , 16.9 , 14.5 , 16.9
Starting at the front of the engine on the drivers side:
11.1 , 16.7 , 5.7 , 7.1
It appears that I have some bad injectors. My question is this:
Do I replace all the injectors or just the ones under 12 ohms?

Thanks,
Lee
Frustrated in Baltimore

 

[Toms007]

I'd replace all of them. I'll find the link to an excellent source for fuel injectors.

 

[milehigreg]

The thread rises from the ashes like a Phoenix! I agree with Tom. I understand that the injector coil windings are exposed to fuel for cooling. The insulation doesn't like ethanol and breaks down. Also, they are 20 years old. They have seen there expected useful life. While you have the plenum, intake runners and fuel rail off, may as well replace them all. Be extrmemely careful of the plastic vacuum tubing. Mine was very brittle and I broke a couple of sections. Good luck!

 

[Black Bart]

You need 3 Injectors to make it run right.
If you are going to do your own work then just installing 3 would not be a bad gamble because the others may run awhile but if you are hiring it done change all of them because their is a good chance that more will fail in a few months
All depends on how much you want to spend now.

 

[Corvette Emma]

I am in the process of replacing all the fuel injectors, like you said, while i'm in there i might as well replace all of them. I am also going to replace the fuel pressure regulator and change the plugs. I figured I would replace the fuel regulator because the car only has 20K miles on it so while I was there I might as well and change it. I also figured since the car probably wasn't running real good because of the injectors I would change the plugs.
I do have one comment I would love to hear suggestions. The lower runner bolts (T-40) are a ***** to get out, any help here? I had to order some special ball and angle T-40 torx tools to try and get them out. I am not complaining because I love my car and do enjoy working on it.

Thanks,
Lee

 

[Achilles]

I am in the process of replacing all the fuel injectors, like you said, while i'm in there i might as well replace all of them. I am also going to replace the fuel pressure regulator and change the plugs. I figured I would replace the fuel regulator because the car only has 20K miles on it so while I was there I might as well and change it. I also figured since the car probably wasn't running real good because of the injectors I would change the plugs.
I do have one comment I would love to hear suggestions. The lower runner bolts (T-40) are a ***** to get out, any help here? I had to order some special ball and angle T-40 torx tools to try and get them out. I am not complaining because I love my car and do enjoy working on it.

Thanks,
Lee

Two ways may help with the Torx bolts: 1) remove the valve cover to allow more clearance for a long extension. 2) I used a 1/4" drive extension that worker perfect.

 

[garyg]

starts and dies

Hi , I'm experiencing the same problem with my '88 C4 ( 50,000 miles ). First I replaced the fuel filter and the air filter, checked the throttle body and it is clean. Got a code 54 reading on the OBD, so I replaced the fuel pump relay ( very easy ). Again, she starts but dies, if I hold down accelorator I can keep her running smoothly, if I let up she dies. Checked the OBD again, no readings other then 12.

 

[milehigreg]

Kindaslow - YOu might want to start your own thread about your crossfire issues. I think your post got lost here. There are some Crossfire gurus on the forum - Geekinavette is very knowledgable.

Corvette Emma - Responded to your PM. If I did it, you can do it!

garyG - maybe the throttle position sensor if you can keep it running with the accellerator depressed?

 

[VETZRUL]

It Still Works!!

Milehigreg,

I found your posting and the attendant replies by a google search with a similar problem. I had three injectors around 3 to 4 Ohms the rest between 16 and 21. Not throwing codes. total puzzlement. I read through the total thread then ordered a 'stock' set of Acel injectors. Installed them and Vroooom away we go (present tense intentional). So the post IS like a Phoenix because it is still a valuable lesson to us "newbees" to C-4's. When I came home from Viet Nam by wife and I bought a '61 with both tops. We both loved it. It was a real firebreather, then came kids. We sold that one for grocery money knowing sooner or later we would get another. Well... nearly 40 years later we have it. It's almost the same color, but has a 6 spd manual box instead of the borg warner T-10.

I was double frustrated by my inability to diagnose our engine. The symptoms I had were start OK cold, but as the engine warmed, it ran rougher and rougher and acted like it was a vacuum leak in a carb system. You guys saved me a ton of time/frustration/cash, and I wanted to thank you and let you know that you're still saving 'vette owners from the brink of dispair. Thank you.

Best Regards

Dave Everett