1964 C10 suddenly running terrible

[62gmc910]

I have been troubleshooting old machines for a long time and most people want to blame the carb and fuel. carbs do three things run lean run right run rich. Lean is usually cut out or jerking, rich is lower power black smoke and flooding. Ignition is more often sporadic and sputtery. if the truck runs ok then quits chances are its ignition. CHECK for spark when it won't run if the spark is other than Blue or blue white it probably won't fire under pressure
if it is orange the coil is suspect
Plug wires for modern electronic ignition don't work well with points
have you checked the point gap , it could be marginal and go out of range when the engine warms up

[taclem]

An older one of mine had a split rubber fuel line from the tank. Would run fine when first started and would run like crap with any demand on fuel when it would start sucking air. Even when I stopped it would run bad until I got the air out of the fuel line. I replaced carb, fuel filters, and even the fuel pump until I found the problem when I lifted the bed to check the lines. Just a thought.

[terd ferguson]

I took mine on it's first full on road test since rebuilding the carb. It did great for around an hour around town and on the highway. So it appears my problems have been solved. Hope yours are too.

[dracko]

Hey guys, thanks for the additional ideas. Problem definitely not solved...drove it for a few days and it stalled/bogged out on me again and has been runnin like crap since. I haven't had a chance to look at it since its like a freakin blizzard here with 4ft. snow drifts and been busy at work. but this week i'm going to go over the electrical, I think i'm just going to buy an HEI igintion and replace the coil for sh#ts and giggles...and go over the fuel system again (check all the lines too, thanks taclem)tired of makin my buddies tow me home!

I took mine on it's first full on road test since rebuilding the carb. It did great for around an hour around town and on the highway. So it appears my problems have been solved. Hope yours are too.

hey man, good to hear all that work paid off!

[dracko]

Well, apparently when I looked in the tank, I didn't look good enough....there was some rust dust in the bottom of the tank afterall and that seems to have been the cause of the phantom running problems. Pretty sure the dust would get stirred up eventually in the tank and then suction onto the pickup filter and starve the truck of gas....then after turning the truck off it'd fall back down to the bottom of the tank and the truck would drive fine again for a while.

After pulling the pickup tube filter off and putting a clear inline fuel filter on, I noticed the gas was orange'ish and I was getting rust crud in the fuel filter at the carb. So had the tank dunked in caustic acid and steamed out, now its clean and the truck is running excellent.

Just want to thank everybody for all the suggestions and help with this! I think the first suggestion was check for rust in the gas tank, lol, live and learn!