I have a 84 dodge d-150 slant 6 225 1bbl carb. Has computer spark control mounted on the breather housing. Engine has a miss through out idle and driving range. dose anyone know what could be causing this? Have already done Have already done all tune up parts.

 

How many miles on the engine? You have the lean burn system. I've changed several over to regular electronic ignition. If the lean burn is the problem, that will fix it. However, there are other things that can cause a miss. Things like a sticking or burnt valve, If you didn't swap the plug wires out, one could be weak. I've seen a miss that hard to find until I noticed it would puke oil out the breather cap. There was a hole burned into the piston head.

The first thing I would do would try to isolate the cylinder. Wear a heavy rubber glove and unplug the spark plug wires one at a time and see if one cylinder makes no difference. It it stumbles more on each cylinder except for #5, your miss is #5. I'd do a compression test on that cylinder. If it's way low, like 20 psi, you have a problem in that cylinder. If it's up higher, like 110 psi, I'd check all the cylinders. I personally like to run a vacuum check on engines. That can tell you a lot about the internals.Things like a sticking valve have definite readings.

 

Dear Ol' Grouch, I will definitely have the compression and the vacuum test done. I kind of thought one of those could be the problem. Yes I did put new wires on. The truck has about 112 thousand miles on it.What would be the best trick to free a stuck valve? I also have one other problem, If the truck is'nt run for a couple of days it has to be cranked a lot to get started. Could this be a leaking diaphragm in the carb or the fuel pump problem? I thank you for your input the problems.

 

One that is easy but timing is critical is to pour a quart of ATF into the engine oil. Drive about a block, NO MORE, then drain it out and refill with fresh oil. If it was a newer engine, I wouldn't do that. Your engine is more robust than newer ones. It may or may not help. The first thing I'd do is unplug one plug wire at a time. That will let you track down where the miss is.

On the extended crank time, Ethanol is in everything and I've seen it eat fuel pumps and carburetors up fast. I put three fuel pumps on an '84 Wagoneer once before I got one that held up. The fuel in the carb or pump might be siphoning back. You might also have a pinhole in the rubber part of the fuel line. That can let you drive but under heavy acceleration it will starve for fuel due to sucking air in. Once you track down where the miss is, use a stethoscope or even a wooden dowel rod to listen inside. Just put the rod against your knuckle and use your knuckle to press the flap of cartilage on your ear shut. You can hear inside just fine but if you bump a moving pulley or belt it won't ram the rod into your ear. I'd do a compression test too, just to make sure.

 

Dear ol' grouch, Thanks again for the feedback I really appreciate.the info.