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Fuel injector problem / question

HPG

Well-known member
Joined
May 24, 2003
Messages
255
Location
Bel Air Md.
Corvette
99 FRC MN6
88 stock L98. 60K miles. starts right up when cold. Hard to start when hot. Cranks several times before starting. No smoke when it does start. Hear a slight pop or rough idle for just a second. Could this be a leaking injector. If so, should you have only the bad one replaced or all eight
 
they were notorious for injector problems you could do an injector drop test or put a fuel gage on the rail and see if you have any pressure drop while sitting should only drop a certain amount in a certain time frame would have to look up the spec:w steve
 
I'm not much of a mechanic, so I'll have to bite the bullet and take it to a real mechanic.
 
Another option than replacing is to have them cleaned. I read something that the majority of issues with injectors wasn't failure; it was that they needed to be cleaned.

If you are replacing them, it is advisible to replace all 8. Last I checked, I think they were in the $70.00 for each injector! :(
 
It could be the injectors but it could also be a bad check valve in the tank.

Check the fuel pressure. See what is us running and how fast if leaks down after shutting off the motor. A leaking injector will allow the pressure to drop quickly but so will a back valve in the tank.

If the tank check valve is the problem, it will be hard to start after it's warmed up but seem to start fine after it's cooled down. I know as I had this problem with a 96 I had. Turned out that the stuff in the tank had picked up some rust and everything back there needed to be replaced.
 
I read somewher that it is not a good idea to use any type of fuel injector cleaner on vettes. Ever hear of that????????
Edmond said:
Another option than replacing is to have them cleaned. I read something that the majority of issues with injectors wasn't failure; it was that they needed to be cleaned.

If you are replacing them, it is advisible to replace all 8. Last I checked, I think they were in the $70.00 for each injector! :(
 
Use Chevron's Techron if you use any kind of additive. Most of the automotive community will agree that it is one of the best additives for fuel injector cleaner on the market. If you use Chevron gasoline on a regular basis, you should only have to run the Techron through the system maybe once a year or so.

Oh, and what you've heard about not using injector cleaners had to do with the seals of some early fuel injectors. I forget what the exact situation was now, but it's usually not an issue anymore.
 
HPG said:
I read somewher that it is not a good idea to use any type of fuel injector cleaner on vettes. Ever hear of that????????

Yes, there is a thread about that here at CAC in the general tech. forum. It said something about Bosch injectors, which your 88' will have, getting the rings worn from additives. I'll look for it and post it here.
 
Here is the quote:

"With '85-88 Bosch injectors, do not use cleaning additives in the gas tank. Fuel-system cleaners are not recommended, by GM, because of the kinds of materials used in the fuel tank bladder, fuel O-rings, and fuel line hoses. If cleaning is required, use the GM specified procedure. On the other hand, Multec injectors, in the '89-01 models, do not need cleaning, and doing so could damage them."

This was taken from Ken's post, which was taken from Charles Probst book "Corvette Fuel Injection."
 
You could use some fuel injector cleaner but don't go crazy because it will harm the injectors. Try it and see if it works, I would also check the fuel pressure and see what it is.
 
Sorry but I had to bring this one back from the dead, because i'm having the same issue here. I always thought that fuel injector cleaners are fine for all cars. My car was running perfect until I used gumout fuel injector cleaner. Mind you I have a 91 C4.

Now I must quote the poster who said, ""With '85-88 Bosch injectors, do not use cleaning additives in the gas tank. Fuel-system cleaners are not recommended, by GM, because of the kinds of materials used in the fuel tank bladder, fuel O-rings, and fuel line hoses. If cleaning is required, use the GM specified procedure. On the other hand, Multec injectors, in the '89-01 models, do not need cleaning, and doing so could damage them."

This was taken from Ken's post, which was taken from Charles Probst book "Corvette Fuel Injection."


thing is I went crazy with the injector fluid. I used this cheap gumout injector cleaner from autozone it was like $5. That's when I started having starting issues, but I didn't think it would be the injector cleaner, since that was suppose to do good and clean the injectors. But any how, I finished the tank, filled her up again and added injector cleaner again. I started having starting issues...and at this time, it will not start any more. Cranks just won't start...and it's not the battery. So I assume it's most likely my injectors are damaged? Could they be simply cleaned or should they all be replaced?
 
Did you replace or check the fuel pressure reg? I had the same problem. It was leaking so slightly I really couldn't tell till I replaced it and cut the old one open. The diaphragm crapped out enough to cause the problem. This was after I sent the injectors out for a cleaning. Static fuel pressure was dropping off and I thought a leaking injector for sure but, someone enlightened me here, thought I'd pass it on. ;shrug
 
I have been told that Chevron with Techron is fine to use on C4's, and that it is the GM addiditive in just a different labeled bottle. I have never had any real experience with other types of injector cleaners. I would put a fuel pressure gauge on and see what kind of pressure you are getting while the motor is cranking.
 
slip in to harbor fright and grab a fuel injection tester for $15....first thing to look at with ANY efi engine is what pressure is available from the pump and how fast it bleeds off when the key is turned off...should hold 10 psi after 12 hours shutdown, minimum (more is better, but few are perfect)
 

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