Hi Guys,

I have a 83 F150 4x4 with an inline 6, 300. This truck is great!

I had a problem with this truck, it was backfiring and hard starting. So I thought it was the Carb, played with the choke for a week or so till I got stranded. I replace the Carb with a (Tomco) and the plugs, rotor & cap. After all that found out the problem was the ingnition module.

Any way ever since then the truck runs rough lacks power and has even overheated once, not to the point of complete steam. I have tried to set the idle and the mixture with a tach. Played with the timing and still have the same problems. Its even worst when it rains. I have taken the vacuum line off the distrubutor and found no vacuum. So I don't know if this is correct or not.

But before the replaced parts and problem this truck ran fine.

So any help of what to look at would be great.

Thank You
Wayne
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You state that you eventually found the problem to be in the ignition module, but you also say it's been rough running & overheating ever since. If both of these statements are both true, how do you know for sure the original problem was with the module?

Are your ignition wires solid copper or the carbon filament type? If they're the carbon type, could you have broken one or more wire filaments when you replaced the distributor cap and pulled the wires out of it? Have the ignition wires ever been replaced? If not, I'd do it. They don't cost much (about $15) and it'll eliminate one major possible source of mis-firing.

Do you have a spout connector coming out of the ignition module cable harness and, if so, is the plug in it tight? With the plug out, engine timing is fixed and would cause very poor performance and possibly overheating at higher than idle speed (because the timing never advances).

And last, because of your comment about the current problems being worse in wet or damp weather, has the ignition coil ever been replaced? Over time, and with the engine heat involved, they can breath in damp air as they cool down after running the engine. This can give you some REALLY strange operating problems. If you've never replaced the coil, I suggest you do it. They typically only cost about $15 or $20 at your local auto store.

 

A couple of other thoughts:

Do you have a vacuum leak someplace? Especially check both the PCV valve and the line that leads to it. I found severe hardening and cracking on the backside (engine side) of this hose, especially in the bends. It doesn't take much of a leak to cause engine roughness because the fuel mix goes very lean.

And, finally, one strange item that finally solved a very annoying problem on my '87 I-6. There's the magnetic pickup coil in the base of the distributor under the cap that drives the ignition module. On my truck, the mounting plate for this pickup is screwed to the side of the distributor and serves as a ground. After MUCH frustration with a random intermittent miss problem, I found a lot of corrosion between this plate and the distributor housing. I cleaned that all out of there by removing the mounting plate, scraping both mating surfaces, and using emery cloth to get down to bare metal. My problem was finally solved ... and it only took me a year to find it!

I'm assuming you're correct in your analysis that the problem is ignition, and not with the new carb you installed. You could always reinstall the old one to eliminate that possibility.

Please post back as to what you find to be your real problem.

 

I will change the Wires tomorrow and see if this helps. I'll let you know what I find.

Thank You

 

Well I tracked down the problem. After you said something about the wires, it seams the person that changed the plugs for me never tighten them up. And also a broken wire was found on # 3.

So all will be well after I set the fuel and idle.

Thanks for the help Traderjoe28.

 

You're welcome.

I'm happy you found the problem. Thanks for posting back.