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Discussion Starter #1
I have a '95 K1500 with a 350 that only sparks when it wants to.
every thing to do with ignition is new, ie, cap, roter, coil, distributor, plugs and wires. what is happing is from time to time it falls flat on it's face with no spark from a stop light or at cruising speeds and putting my foot into it, I have to put it to the floor and within a few seconds it will start to spark, shoot out a bunch of black smoke run only on a few cylinders then slowly get back to running smooth. the truck dose not run like this all the time, but has been getting worse and is still doing it after replacing everything I can think of. I have noticed with the timing light that the timing retards about 10* when this happens in the driveway, and as it slowly starts running again the timing slowly starts climbing back to were it should be.
also it looks like I'm getting weak spark at idol that gets stronger as the rpm rises.

any and all help troubleshooting this will definitely help with my mental stability, thank you all in advance
 

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Discussion Starter #3
You cam is messed up. It's feeding the distributer gear wrong. Time for a rebuild!

Aw man, please don't tell me that :suicide2:

are you sure, this has ben going on for years now and a cap and rotor fixes it every time except this time, not to mention the problem comes and goes, I would tend to think if the cam was gone it would be not run good at all??
 

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Aw man, please don't tell me that :suicide2:

are you sure, this has ben going on for years now and a cap and rotor fixes it every time except this time, not to mention the problem comes and goes, I would tend to think if the cam was gone it would be not run good at all??
Well it could be bad humidity in your cap/rotor causing the horrible misfiring.... but I doubt it. Your cap/rotor could also be grounding out somehow but I don't know how it really would. You said it is getting worse! It sounds like internal damage to the cam. You could just do a cam swap and not rebuild the whole engine if needed since you said everything on the ignition side is brand new!
 

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If it runs fine sometimes, and crappy others, I doubt it's mechanical. What kind of plugs? GMs like AC Delco best, with a small gap. Had Bosch+4 in mine this winter. Total garbage. Also, there is probably a vent in the bottom of the distributor. Knock out the screen if it's still in there. Are you using genuine GM ignition parts all around? I've learned from others that AC Delco is the only way to go. They were actually cheaper than the Napa stuff. NAPA premium wires are OK though.
 

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I have a similar problem with my 95 305, It is on its 2nd distributer in 25k miles and is out of time AGAIN. The last distributer was put in at 185K miles has 197k now. Sounds like you have the same problem, I would like to know what the heck is going on.
 
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