Help, White Magic truck mount engine spitting and misfiring

This could be a number of things happening. Some problems you may want to look at would be faulty O2 sensors, Timing issue with the distributor, bad distributor cap and rotor, fuel pressure regulator, fuel filter, Faulty MAF, ECU running cold/open loop could be applying the wrong A/F ratio.

Becuase it is fuel injection , your injectors may simply need to be cleaned.

I would start with a fresh set of spark plugs. Then go from there.

how does the vehicle it is mounted in run?

Could be a vacuum leak. Something on the intake could have a leak. Does it have emission lines? I thought white magic only had direct drives?

try to reset your ECM
check your fuel line filter

have you tried misting water on the spark plug wires? It could also be cross firing. Or a bad misfire somewhere. Try pulling the plugs out one at a time. The bad cylander will not change and rpm or problem will still be there. That is how you find the bad cylander.

Have you checked the timing with a timing light?

You can rent a timing light from an auto parts store. No way that would disrupt timing.

Whats the condition of the distributor cap and rotor?

Its quite simple to remove the cap to have a look see. Just dont overtighten it when putting it back is all. I bet thats your problem.

The only thing you can do on that engine as far as a tune-up goes is to replace the plugs and wires. There is no dist cap or rotor.

I am with Ara's line of thinking on a vac leak. To check for a vac leak, Rob, run the machine and then spray around the intake manifold/throttle body area with carb cleaner, if there is a leak, the engine rpm will smooth out for a second when the carb cleaner enters the leak.

On a similar note, my wifes Explorer started running like doo-doo in the morning, but would run fine once it warmed up. I took it to 2 mechanics who could not figure it out, I ended up taking off the intake manifold and found one of the o-rings had a chunk out of it. I bought the $20 gasket kit from NAPA, put the manifold back together and it runs great.

Thats why im glad we have you around Chris. This is why I need service manuals for these truckmounts. So I can give proper feedback. Half the the time I gather diagnostics from my head without know exactly what the setup is. My brain is like a diagnostic tool that spits out info like a printer.

Some of these manuals are hard to come by and the TM manufacturers don't usually include service manuals for the engines. I only have one custy who has this Ford fuel injected engine, so I am not too familiar with it myself.

If we put our heads together Ara, we can solve alot of this stuff!