The Proverbial No Fuel After Sitting.

I know this has been talked about many times before, including me responding, but for the life of me I can’t find the tread. So.........

Yesterday was the day. Willy has been sitting for 4-6 weeks. As I figured, he would not start. So I looked down the carb while pumping the throttle and no squirt. I tried and tried cranking. The fuel filter right before the fuel pump showed fuel in it and full. I even tried starting fluid but it would fire for just a second on the mist. Finally even had to jump the battery. So I finally pulled the fuel line off the carb as I cranked it and with thumb over the line, I could feel a little pressure. A fair amount of cranking and finally the gas came out of the line. Hooked it back up and a final crank and Willy started up instantly and ran. So either the the fuel in the bowl evaporated or siphined down, AND fuel in the line between pump and carb was empty. But it took a lot of cranking to get it filled up. So ideas? I am convinced to add an electric on a push button to avoid this in the future.

 

It’s possible your needle valve stuck shut. The air in the pump/line couldn’t vent through the carb and it was basically vapor locked until you broke the seal. After there was fuel in the pump, then it had enough hydraulic force to pop the valve open and fill the carb.

That’s my theory and I'm sticking to it.

 

8 oz Soft Face Hammer - 57-594 | STANLEY Tools

 

Trail ride I was just on an m38a1 had a fussy float/ needle valve. The tapping technique was applied several times, worked well...

 

Inline outboard primer bulb works well.

Two squeezes and you’re in business.

 

It even works on TBI.

 

I tried that early on with a plastic screw driver handle, thinking the same thing.

 

My Bobcat has one of those that I have to use when it’s sat for awhile too.

 

As has been mentioned before, the M38A1 fuel pump has a built-in primer, with a lever that could be connected to a dashboard cable control, if this problem really is bothersome.

But I would be wondering why thousands of other F-heads over many decades have managed without much trouble.

After sitting several months, mine will fire up in about 10 to 15 seconds of cranking, on a six volt battery.

"Most carb problems are electrical." Keeping the plugs, points, cap and rotor (and timing), tuned up has always been my best approach to easy starting.

 

This was definitely not electrical. It was fuel. It is a replacement fuel pump from Walcks. I have no idea where it came from, but I did find one of the original glass bowl ones that’s been rebuilt. I’ve been planning on switching so I guess nows as good of time as any. And then next time it sits for extended period I’ll know if that solved the mystery.

 

I like the glass bowl type - it has often helped me diagnose or monitor an issue.