Leaking fuel shutoff

[labjack]

I know this has been discussed before but I have a screw-type gas shutoff that leaks when it is opened, but not when shut. Anyone know off the top of their head what the fix is for this? It's a 4 cyl 4000 gasser.
Thanks for your help.

Mark

 

[pomester]

Drain fuel tank -

Remove the fuel line from the valve, 7/16" fitting, you might need to shorten a wrench.

Remove valve from tank - generally the most difficult part of the job. Clearances are tight. Two #10 bolts hold the valve to the tank, I think they are 3/8" heads.

Take valve to the bench, use a small chisel or pair of side-cuts to remove the rivet that retains the screw part of the valve.

With the rivet out of the way, unscrew the valve.

Clean parts, including the O-ring sealing surface on the bottom of the tank.

Tap the valve body (the rivet hole) for a #8-32 or #10-32 flat head screw. Said screws need to be 5/16" long. Clean.

Replace the O-ring on the valve screw with a #009 ring. Lightly grease O-ring and screw and install in valve body.

Install the #8/#10 screw in the tapped rivet hole to retain the valve screw.

Place a #115 O-ring into the groove on the top surface of the valve and hold it in place with a bit of grease.

Install valve assembly into tank. Generally the second most difficult part of the job.

Install fuel line to valve.

This thread has some pictures - https://forums.yesterdaystractors.com/viewtopic.php?t=1474661

 

[labjack]

Wow, thanks for the detailed answer! Very much appreciated.

Mark

 

[MarkB_MI]

Regular diagonal-cutting pliers won't grab the rivet. Try to find flush-cutting side cutters. The pliers I have are commonly called cherry rivet cutters. You'll find plenty of uses for them.
Rivet trimmer

 

[labjack]

Thanks for the tip.

 

[texfordfan]

Very good info. I also found that removing the valve cover by unbolting it and rotating out gave me a lot more space to work with.