Need a little help here. I have a 1989 Jeep wrangler with a 4.2 straight six. The starter cranks the engine fast, I have a good spark and compression is at 150 PSI but the engine wont fire.
I looked at the rockers and they were moving so I am guessing the timing chain is ok...
I tried priming it with a capful of gas to the carb but it only fired once then began to turn fast again. I have a mechanical fuel pump.
If you're getting spark I would take another look at the fuel. It's possible your fuel pump is bad or you might just have a clogged filter. You can disconnect the line and see if fuel is pushing through. The first, easiest and least expensive thing to do is to first replace the fuel filter. If the problem continues, check the fuel pump. If that's functioning properly it could be the carb. itself, especially if it's original. I'm not understanding exactly what you mean by "turning fast". Are you trying to say that the starter is turning the engine the way it's supposed to?
Take off the air cleaner and try some priming the engine with starting fluid or with a SMALL amount of gas. If it starts and tries to run you KNOW the problem is fuel related. Then check out the fuel delivery system before throwing money at it; fuel filter, fuel pump, gas lines to the carb and to the fuel tank for damage, fuel tank, and etc. If it doesn't try to start, look at the ignition system.
If it ain't broke, don't fix it - Don't worry, something will break soon enough for you to fix!
thanks for the input guys. I replaced the fuel filter and the fuel pump is working fine. I will check the timing chain to see if it skipped a few teeth. Never thought of that since I saw the rocker arms moving. Forgot to mention I got rid of the stock carburetor and replaced it with a Weber two stage.
I replaced all plugs rotor and distributer cap.