Why wasn't my engine getting fuel?

Question

This is a 1975 Ford F-350. It has been sitting idle for 6 months, and is rarely used.

Normally, when I try to start it after sitting for a long time, it takes a bit of cranking before it starts. I assume this means the fuel in the fuel line and carburetor float bowls evaporates, and has to be replenished.

This time, it wouldn't start despite extended cranking.

I manually added a teaspoon of fuel directly to the carburetor, cranked the engine, and it ran for a few seconds. So I knew that compression, timing, and spark were OK, and that it was a fuel issue.

I disconnected the fuel line from the carburetor. The end of the fuel line, and the brass fitting it connected to, were both glistening, suggesting there was moisture. I put the fuel line in a can, cranked the engine, and saw fuel squirt out.

I reconnected the fuel line, and poured a little more fuel in to the carburetor. Cranked the engine, and it started up and ran fine.

What happened? What changed when I disconnected & reconnected the fuel line?

Answer 1

A likely culprit is a sticking fuel float or needle valve assembly. The valve may have been stuck in the full fuel bowl position, or a piece of sediment may have blocked the port. The vibration caused by taking off the fuel line could have cleared something like that. If it happens again, try rapping on the carb with a screwdriver handle -- that may dislodge the float and allow you to start the engine.