I have an 86' CJ-7 that shuts down whenever it feels like it. Example: I am driving down the road, 55MPH, and she just shuts down. Not a power problem, i.e. the lights are still on, radio playing, etc. Not a fuel problem, replaced fuel pump and filter, carb is getting plenty of fuel. I do not understand. Some times after it shuts down, it will start right up again, and sometimes, it takes a couple minutes of cranking. No backfiring, runs great, until it shuts down. I dare not drive it, because I have held up traffic quite a few times. No upgrades done yet. Any advice would be welcome.
well it can be as simple as replacing the gas cap, but i would try that first. What you are describing sounds like fuel starvation. Normally the first responce is always replacing the fuel pump, but since that has already been done, then the problem is that the pump is not being allowed to pump the required fuel. This could be due to a vapor lock in the fuel lines, but that usually occurs between shut down and restart. But if vacuum builds up inside the fuel tank, due to stuck or clogged cap or malfunctioning check valve or charcoal canister, that resists the suction of the pump.
Sounds like your coil is dying. It gets hot, creates an open and dies because you lose spark. Then, it cools a while, makes contact again, and your off and running. Simple fix, about 40 bucks for an MSD blaster or similar.
To troubleshoot, get it to where it dies, then quickly pull and test the coil with an ohmmeter, it should be open. If you can heat the coil significantly while it's out of the vehicle, you could test this way also.
You can pull the coil and put it in a 200 degree F oven (lowest temp setting) for half an hour or so to simulate underhood temp conditons. If your real slick, you could have the ohmetter hooked up to it in the oven and watch it as the temp rises. But this might melt test leads and what not, use discretion if attempting this method. I would make some dummy leads out of high temp wire and run them out of the oven so you don't risk any of your ohmmeter test leads.
Depending on your budget and time, this method could take longer than just swapping in a known "good" coil and testing it in the same circumstances it is currently failing in. However, if you buy a new part and it's "not" the problem, most electrical parts cannot be returned, which is why troubleshooting may be worthwhile effort.
If not this, still sounds like a temperature related issue in a component going to or controlling the coil, like the ignition box.
I don't beleive it to be a cap and rotor issue or it would die and stay dead.
The ignition coil is brand new so it should be working fine. I will try mounting it on the fire wall or the fender well to keep it away from the hot engine. If this works, I will then get a new coil. Think that will work?
I agree with the ignition module answer since you stated the coil is new. If you cannot find one, say so, I'll dig through my old jeep parts. I think I have a new one that I put on after a total rebuild, not sure.
I went to a MSD ignition module and love it, consider this an option if your shelling out the bucks for an ignition module, upgrade to it over spending the same money for a OEM part you know "will" eventually fail.
I agree, its probably the module. Mine did the exact same thing last year. I actually carry a spare now. They are pretty cheap at AutoZone with a lifetime warranty for whatever that's worth-doesn't do much good in the boonies.