Ok guys, here's a good one for you-83 Dodge D150, slant 6, manual tranny, engine starts fine when cold, as it warms up starts to miss (idling or driving) then dies and won't start again (till it's completely cold) Breaks up and backfires thru the carb when you try to accelerate. The problem cropped up gradually, at first it just missed when it was hot, I shut it off and restarted it, but it got worse and worse. The following are less than 1000 miles old on the engine-plugs, wires, cap, rotor, pcv, fuel pump, filters, I replaced the carb with one from the junkyard (earlier vintage) and it started up and ran very smoothly til it got hot, then the same results. Right now I'm assuming something electrical, I sprayed out the cap and inside the distributor with wd40, as there was some condensation present, but no effect there either. This was a great running truck till a week ago when all this started happening. At first I thought it was carburation, (the automatic choke is working flawlessly) but now I'm not so sure. Let me know what you guys think.

Check for a vacuum leak before you do anything drastic.

Hey do you have electronic ignition??

Usually ignition modules start missing when hot but work fine when cold.

just a suggestion...

yes, it's an 83, electronic ignition and dual pickup coils in the distributor

You could have a "hot short" in the ignition coil. Do you have another coil you can try?
Welcome to the board.
Bob D

I have two suggestions: First, the ignition module/coil/pickup. Replacing those one at a time is the way I would tackle that Those can "hot fail" like someone already said. My other suggestion is checking the rest of the fuel system. The pickup in the tank can become clogged over time. Another possibility is that there is something in the tank that periodically blocks the pickup. It can run a while then shut off. I had this happen on a car I used to own, and it drove me crazy until I fixed it. If you drop the tank, used compressed air and blow through the lines (disconnect the line that feeds the fuel pump first) to expel debris trapped in them.

This will probably suck compared to other jobs, as some of the gas tank bolts will probably spin when you try to loosen the nuts. You just have to do it anyway if the ignition checks out. The popping through the carburetor sounds like it's really lean to me, though both that and ignition problems can cause carburetor backfires. If it comes to dropping the tank, I gained some experience on my '78. First, be prepared to cut some of the bolts/nuts that hold the tank in. If your truck is like mine, there will be 3 straps holding the tank in, and each strap will have 2 bolts going through it with a nut on each bolt. These will be facing down toward the ground. When you try to loosen the nuts, the bolts will probably spin. Getting to the bolt heads to put a wrench on them while loosening the nut will be impossible in most cases because the tank itself blocks access. This is why I cut many of them off. What I did to keep them from spinning the next time they're loosened was to tack weld the boltheads to the frame while the tank was out. That immobilized them so that I can simply loosen the nut the next time I need to drop the tank for some reason.

Dual pick-ups in the dist = Lean burn. Ugh.... I'd definitely start looking for vacuum leaks.

If your computer is in the same place as my '87 (under driver's side fender, behind battery) check the vacuum pot on the computer--it controls your idle and off-idle timing advance, make sure the line between this vacuum pot and the carb is good.

Is the egr valve hooked up? You can disable it by turning it over (180*). If the egr and diverter valve are not working correctly it will backfire (my experience has been thru the pipes though, not the carb)

Good luck.

-S/6

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The "Silver Bullet"
87 Ram D150

checked all over for vac leaks, replaced the coil with a new one, same result. It's getting plenty of fuel, strong squirts from the accelerator pump, runs fine when cold, still breaks up worse and worse till it finally stalls and won't restart. Talked to a couple of reputable local mechanics and they both immediately said "ignition module" which in my case is on the air cleaner assembly, and costs a whole bunch ($94 +$90 core is the lowest price I found) Will order one and see what happens. Driving my son's Hyundai till I get it fixed, geez, I really miss my truck. Thanks guys for all your help, and I'll keep you abreast of what happens, but please post if you have any new ideas.

It's possible the pick-up coil in the distributor is bad/going bad. Does yours have two coil? If so there will be 4 wires or two connectors on the distributor. One coil is START, the other is RUN. On my 87 truck the RUN coil had problems and the ESA comptuer is programed to switch to the START coil when the RUN coil fails. This will allow the engine to run but at reduced performance and fixed ignition timing. Mine worked fine when cold but after 2 miles it warmed up enough that the RUN coil failed and it switched over to the START coil. It did this exactly the same every day for a week while I waited for the new coil assembly to come in.

...on something with a catalytic converter, I always like to go 'round back and see how the exhaust is blowing out on a fast idle if it's running funky. Never hurts to check that. Motors don't run too good when half the exhaust is trying to blow back up the intake.

"DW"

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If it ain't broke, fix it!