I need help with this one.

I'm driving to work and the jeep starts running irradically - as if it were to stall. The tach jumps all the way and buries itself a couple of times, the it backfires a couple of times, then it dies. I couldn't start her back up immediately and no power. There was power to the lights but none to the gauges. Luckily I was able to pull off on to the shoulder and sit. Not the best place to be hanging out at 7:45 am, I guess only Billy can vouch that on the on ramp of 95 from 595 at that time of day is not the place to be. I was actually terrified that someone in a rush to work would not notice my hazzards and mistake me for braking and run smack into me. Scary three and a half minutes.
Fortunately, after a couple of kind words - I told the jeep I'd find her a warm garage when we move to Pitts, she started right up. No longer sluggish but she did backfire a couple times.
What causes backfiring and why did the electrical cut out? My battery, according the volt meter is 14, my fuel filters (one beside my carb and the other immediately out of my tank) are clean. I'm currently getting about 5-6 psi from my fuel pump into my carb. I can see if there was something blocking a fuel line that would cause the jeep to stall out. But why would it effect the power, or rather the lack of power.
What I did notice before the jeep momentarily died was that it backfired the tach spiked. Is my HEI crapping out? If it is how is that affecting my fuel problem.
Could this be a coincidental electric fuel pump and HEI mess up? Is my 2G requiring adjustment? I need to fix this tonight I wasn't very happy with my drive into work this morning.
Any and all information you guys have is much appreciated.
Thanks, Marc

 

or coil break down. One of the two, leaning more towards module but you never know. Got any ECJ5 friends locally with known good parts to try swapping in? 8)

 

Yeah this guy named Billy but he runs a 4. Wait Jon, you're suggesting swapping in an F-head? Ha.
Yeah I was leaning towards the damned module - again. I was having difficulty last year with this, Billy came over and we determined that it was the module or rotor or something so I simply dropped in a new GM HEI. And everything worked, no more starting problems. But this seems to be different symptoms - the spiking and the backfiring and the dying. If it comes to dropping in another HEI or at least a module then I'll do it again. Will a bad HEI module or a bad HEI stall out the jeep after backfiriing like that? What causes backfiring? Too rich?

 

Seems to sound like a grounding out problem to me.
That would explain the tach pegging and the cutting out.
I could be wrong though.
I'd trace the wires from the HEI and check the ground off the battery.

edit: The back fire could be that fuel was still dumping because you had the gas pedal down and then when the HEI kicked back in it had raw fuel in the pipes.

 

x2. Had a similar problem with my '64 Chevy truck.... Wire under the dash was shorting out sporadically.

 

Sure sounds like timing. But why did the dash lights and tach go haywire? Is the engine still backfiring without the other symptoms? Has it reoccurred? I had a Bronco once that on washboard roads or towing heavy loads the Ignition would cut out (just as if I turned the key off then back on) it would buck, then I would get one backfire sometimes and I would be on my way. This drove me crazy, I looked for a year until one day I was working underneath and saw a ignition hot wire that was slightly crimped next to the engine. I know I looked at that wire before but from under looking up I saw it. A little electricians tape and repositioned the wire and problem was solved. Your problem sounds electrical, could the tach wire be shorting or grounding, that could show up as erratic gage and ignition misfire. It sound like a couple of issues but I don't believe in coincidence.

 

Another thing to look at is the coil pickup in the distributor. This unit rotates with ignition advance. Check the wires real close, as in feel them from one end to the other. It's common for the wires to break inside the insulation and when the distributor advances, the wires don't make a good connection and you get similar symptoms as you describe. When the engine tries to die, the advance comes back to idle position and the wires can reconnect and allow the engine to run. The wires can look fine visually but if you feel the wires you can usually feel an anomaly. Not saying this is THE problem, but one to check that can be a nightmare to track down on HEI distributors. Nickmil.