84CJ Cranks, Starts, then DIES!

84CJ Cranks, Starts, then DIES!


Boston, MA
1984 Jeep CJ-7 6cyl 5spd
Ok, so here's the deal...

Over the winter I did a tub swap. I tried to leave most everything intact under the hood as to avoid the exact situation I'm in now...

I turn the ignition to 'start' and it cranks. It will fire, then the second I let it recoil into the 'run' position, the car dies.

What I've done so far:
I replaced all the old fuel line,
fuel filter,
and done an oil change...

My battery won't hold a charge, but I'd rather not put $100 into a new one to destroy it by testing. If this thing fires, I'll drive it down the street and get a new one! For now, the old piece of :censored: is on a perpetual trickle charge.

The only things connected under the dash are the ignition plugs and rear harness plug. Everything else is unplugged. I read about a "TAC" wire that causes a ton of issues, but I'm not sure what is it, where it is or what it goes to.

There are a number of melted plugs under the hood... but then again, lots of the gauge senders were disconnected (by the PO... before I drove it home).

I'm pretty sure the PO... or his gnarly friends did the "nutter bypass." But, I'm not sure how WELL they performed it. All I know is I'm going to have to redo all their butt-connectors!

If someone could kindly walk me through a minimum set of requirements to get this thing running, I'd appreciate it!

Please let me know if there're any pictures or further descriptions I can get to help you guys out!!!

On a side note: There's a 12G yellow wire factory spliced into my chassis harness by the ignition switch. It hasn't got a connector on it, it's just loose under the dash. It doesn't show up on my diagram... haven't a clue!
Do you have a volt ohm meter and do you know how to use it??:cool:
do you still have the carter two barrel carb??

Will it run if you can get it past idle RPM?

My J-10 has been giving me fits all weekend with symptoms like you have, it was the carb.:D
I do have the carter 2-barrel.

I've never been able to push it past idle. Maybe my new fuel tank, lines and some carb cleaner will do the trick...

What was it about your carb? Dirty?

I have a sneaky suspiscion it's something electrical........ man, I hope I'm wrong!!!
My 84 did the same thing it ran great and I parked it for like 2 to 3 weeks went out to start it and it would crank start then die I replaced and checked everything the problem was the carb needed rebuilt the rebuild kit was like 12 bucks and now it runs great. Those carbs are junk.
It figures...I was just in and out of re-wiring my this weekend and saw so many wires I felt like Jimmy Hendrix was my best friend. I think, don't take it for the gospel but I think mine had a 10gauge yellow wire that went to the tach. Maybe it helps.
So, I found this little gem while pouring over the wiring diagram for the 100th time. I plugged them into each other and we'll see tomorrow if it does the trick!
So, I solved the issue!

In the set of dashboard components, you'll find a 12G RED W/Tr wire coming from the ignition plug. There's also a similar wire farther down the harness. These are the part of the series "Run" circuit that goes through the tachometer. Since I have yet to reinstall my gauges, this circuit was left open. Upon connecting the two together, the Jeep runs perfectly!

Thanks for all your help!


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