'80 D50 Fuel/Carb Problem

Exactly how much fuel pressure do you have and why did you replace the pump to begin with? It sounds to me like no fuel is flowing into or through the carb.

The guy who rebuilt the carb for me said that the reason the truck took so long to crank when it had been sitting on an incline was that old fuel pumps lose their seal, allowing the gas to slowly run back down toward the tank. I don't know how much pressure I have; when I checked the flow, I held a regular plastic cup and the stream of fuel was hitting the center from just outside the edge (2-3 inches). Anything else I need to check?

How long ago was the carb rebuilt and did the engine ever run after the rebuild? Was the engine sitting for any length of time before this problem came into existence?

Carb was rebuilt about two months ago. The truck ran fairly well except for the hard cranking occasional sputter. The engine did not sit for any amount of time. Another friend said that I may have gotten trash in the jets when I installed the new pump. I blew them out with no change, then he said to check the float level. According to my Haynes manual, the level should be

787, but according to the way I understand the book that's not possible. I did get it close, and the truck will run now, but not well at all. It has very little power and stalls and backfires under load. Any suggestions for setting float level? Is this indicative of a vacuum leak too?

Jester

Back firing is always caused by a lean condition. Maybe you should have a carb rebuilder clean. They have some real mean cleaners and jet washers. There is a trick that I learned from a junkyard worker. I never believed would work until I tried it. You'll need an assistant. Find or make a tight fitting cover for the top of the carb. I made mine from the bottom of a motor oil bottle. Rev the engine very high, like

5000 rpm and while holding the throttle wide open, stick the cover on and don't release throttle until the engine dies. The huge vacuum effect can actually suck out trash in the all the little tubes and jets. MAKE SURE you use something good and tough. I tried my hands one time, It HURTS, and leaves a big ass hickey on your hands.

I tried it on an old rover that I had been screwing with and could not get the fuel right, no power under load. I tried this trick as a last resort. There was a HUGE difference in the way it ran after that. I've done this a couple more time on junkyard cars and it really does work pretty well.

Clay

Thanks for the tip. I did take all the jets out and the needle and all were spotless, but I will try that too to make sure there is nothing else in there. On setting float height, am I supposed to measure from the top of the float (if the throttle body is upside down) to the flat of the body, or from the bottom of the float to the indention where it goes?

It's not the stuff you can remove that's the problem, it's the internal tubes and vents that are. As to the float height, if you can find a service manual, it should have a diagram.

Clay