1981 c10 250 i6 not running

[jairie laplante]

hello i have a 81 c10 with the 250 i6. i bought the truck not that long ago and i was told that it wasn't getting fuel. the guy before me replaced the fuel pump but when i went under the truck there was big holes in the fuel lines so i replaced them. after that i figured it would run because now its pulling fuel from the tank. but for some reason it wont idle (i need to hold the gas a little) and when i try to move it it does right away when letting go of the clutch. so i was wondering what it might need because im new to these old trucks so i dont have a lot of experience but i want to fix it so i can drive it

 

[AuroraGirl]

I know your truck PROBABLY needs a new carb or a rebuild on the monojet(it has a stock rochester/carter monojet, yes?) and you would also benefit from simple tune up items. I could be wrong, but if the previous owner couldnt figure out there were large fuel line holes he probably didnt believe in spark plugs or maintenance schedules. Once you do cap, rotor, wires, spark plugs and you get a carb rebuilt you should see an improvement. when doing this work, replacing and and all vacuum lines on your engine will help.

Can we see your engine bay and engine and pics of your fuel pump and maybe the lines you fixed? Im thinking you may have improperly routed emissions equipment, just based on experience with people who play with things on the engine and dont know left from right

 

[1987 GMC Jimmy]

The first thing I’d do is check that you’re getting good fuel from the pump. You can eyeball test it volumetrically by feeding the pump via a fuel can into a bottle to see it pump or send it to the carb to see if it runs better. You can also pressure test it, which is the more precise option. 250/292 pumps are direct-to-eccentric driven rather than having a pushrod as an intermediary, and people have come on here a few times with worn down cam eccentrics and no fuel flow because of it. I’d also like to see vacuum stuff and rule out any leaks from lines, accessories, brake booster, and carb base.