1986 C4 L98 Corvette Tune Port. I've changed the same injector 3 times now, it runs good for about 5 seconds and then starts to skip. Once I turn the car off, I turn the fuel pump back on and I can hear an injector that is stuck open. It's done this to the same injector 2 times now and im beginning to really question what it could be. Anyone had a similar problem before?

 

all ive gathered so far is possible high fuel pressure that blows the injector?

 

Hi

Even the standard multec injectors can handle 50 psi fuel pressure, i know that because i ran 48 psi for many years untill i changed to the bosch 111 injectors.

I have come across bad electrical connectors on the harness that connect to the fuel injectors, usually we tend to pull the wires to unplug the harness connector from the injector that can damage the tiny metal strip inside the connector.

I recommend you start the engine when stone cold, run it for ten or twenty seconds and then check each header pipe an inch from the head. If there is a problem with a cylinder it will be cold, that way you can narrow down where the problem is.

Spark plugs can foul up, that is the most common problem for a rough running engine. Double check the ignition leads, use a multimeter to check resistance.

You say you run the fuel pump?

Do you mean you start the car, then it stalls?
Remember the ecm allows the fuel pump relay to operate for a few seconds to start the car, then if it senses there are ignition reference pulses will energise the fuel pump relay.

Remember the injectors "batch fire" that means all will fire together, swap the harness from one injector to the other for a test.

The injector harness electrical connectors are cheap and available at most auto part shops.

Check your fuel pump, they will stop working or run erraticly then fail all together.

Do you have a fuel pressure gauge? check the pressure is around 38 psi that is the standard pressure.

You can run the fuel pump via the aldl connector under the dash,
The bottom far left pin (G) is the fuel pump test connector.
Apply 12 volts to terminal G and the fuel pump will runn untill you disconnect it.

Below is a link to a page with the aldl picture.

http://www.corvettebuyers.com/c4vettes/ecm.htm

Here is the fuel pump relay diagram.

 

I have the fuel pump wired through a switch to remotely turn it on because of an earlier issue, it ran really well for a about a half an hour. I shut the car off and went to move it the next day and could barely keep it running. ill check the plug on the end of the injector tomorrow and see if it has any damage. thanks!

 

The injector is open even if i unplug it. I have the plug on the end of the injector completely removed and fuel begins spraying through it while all the others are shut.

 

SO the fuel pump circuit is jerry-rigged and you are wondering why you are having issues?