Awhile back I mean along while back lol I put a new timing chain, water pump on my dads 1980 F-150 w/ 302. Well it ran fine until a few weeks ago. It got to were you would go up the road and it would cut out bad enough you couldnt get up a small hill. The carb that was on it was pretty old so we put a new one on it. It ran good for awhile ,but now its back to doing the same old thing. If you barely hold the gas or at idle it runs great, put it futher down or to the floor then it starts wanting to die and blowing black smoke. So I let it idle then got under the hood, while looking down into the carb it was only shooting a lil' gas at a time, like every few seconds. So I figured it was fuel related, got a new carb, fuelpump and filter. Put all that on it fired right up and ran good, shut it off and had to whind on it atleast 15 seconds before it would fire again, sounded like it couldnt catch up. When it did fire I drove it , and it was missing/stumbling again with black smoke, so when i got it back it cut it off and now it wont fire period. My suggestion is retire the truck {never liked it } it has to have over 300,000 on it, but my dad wont do it. So I gotta fix it. Sorry for the long post but any help would be great.

 

check float levels, and check timing. make sure the choke is staying open under load. also could be a stuck needle and seat on the carb or excessive fuel pressure.

 

i would suspect timing, it should be about 8*btdc with vacum plugged. I would also run a compression check on that motor having so many miles. when was it tuned up last with new plugs/wires,cap and rotor? along with points and condenser. especially with it loading up like that those plugs gotta be fouled

 

It was tuned up a few months ago, new plugs,wires,rotor,and cap.

 

check and make sure egr valve isn't sticking open.

 

Well I had a mechanic friend help me look at it, and finally traced it down to the choke in the carb, from the factory they had the spring installed backwards, , fixed that and so far so good. Ill see if it last .