Expert: Kevin Pilotte - 8/19/2008

Question
Have a 72 cj5 that will crank but wont fire. Used starter fluid and only get loud popping from the carb. I assume that means spark. I checked #1 plug n no fire. new wires, cap, points, and ignition coil. Any idea of causes and solutions?

Answer
You need three things happening at the right time to get your engine running.
1) Gas. Is the carburetor getting gas into the engine? Look down the throttle and mash the gas. You should see a stream from the accelerator pedal. If you do, you should at least have gas into the cylinders, provided it's not flooding. If you don't see any gas from the accelerator pump nozzle, check to see if the fuel pump is getting gas to the carburetor.
2) Spark. Pull the center wire from the distributor cap and hold it 1/4" from the block. Have someone crank the engine. Should see a strong spark. If not, check your primary circuit of the ignition system.(points, condensor, ignition coil, etc) If you have spark going to the distributor, check to see if you have spark at ALL the cylinders. Check the cap and rotor. Make sure the wires are in the proper firing order in the cap, too.
3) Compression. If you have spark & gas, pull the plugs and perform a compression test.
Let know what happens.