I have a 1995 YJ which I have built from boxes. It is powered by a 258 with a HEI distributor, Holley 2d projection system, Offenhauser intake and tri-y header. My assistance is needed with a start problem. The jeep ran good for about 500 miles and thats when my GREMLINS started! It will start but as soon as I let the key return to run the engine dies. I called Holley and they told me to check for a tach signal, so I did and there is one. The manual for the 2D system said if there is tach signal then replace the ECU. I shelled out the 300+ bucks on a new ECU and installed it. The Jeep is doing the same thing with the new unit in.
I went as far as running new wires(temporarily) to a separate ignition switch and put the HEI on a toggle switch to isolate any of the wire-harness of the vehicle so there would be no chance of broken or shorted wires to interfere with the computer: yet, the problem is still there. I also have grounds from the battery to the block and body: which, I know could cause this issue.