stripped sending unit screws in plastic tank

[JHouk]

Getting ready to launch my 88 V20 for the summer. I've been working on it for 2 years & is now sea worthy. Took it on a trial run in the river, boat ran awesome but it had a slight fuel smell. Turned out to be the sending unit gasket. It turns out all the screws are stripped. Its a plastic tank. I'm going to try the next size screw to see if I can get them to grab. Any ideas?
Thanks in advance.

[smokeonthewater]

Yup bigger screws

[13Echo70271]

Had the same thing. but the screws were just corroded to a smaller size. the brass nut inserts in the tank were good. I cleaned the hole etc. with wd40 and a small pick. ran a bottoming tap to clean the nut threads, put new screws in with a new gasket.

[bgreene]

Yup, surprisingly delicate assembly given the importance of that fixture.

Like using string to connect to wrecking ball.......not enough hardware.

Got lucky myself by tightening with wrench.........the screwdriver head slot won't allow enough torque...

Total assembly connection to gas tank should have been much more robust.

[Destroyer]

Isn't that why they make non-hardening Form-a-gasket? I never put in a gasket without first coating the surfaces with that stuff. (Head and exhaust gaskets excepted). You don't need excessive torque when using it, and it's gas and oil resistance makes it idea for applications like this.

[Blue_Runner]

I get seepage around the sending unit if I overfill the tank for that very reason. Once I burn off a few gallons it stops. I literally just resorted to using a fuel rated form-a-gasket. Haven't totally filled the tank yet so I can't comment on whether it worked or not. Will report back on this thread.

[JHouk]

Thanks for all the feedback,
The Original threads on the tank were just absolutely shot. I drilled each hole out very carefully & put expandable fittings in. It worked like a charm.

[bgreene]

Isn't that why they make non-hardening Form-a-gasket? I never put in a gasket without first coating the surfaces with that stuff. (Head and exhaust gaskets excepted). You don't need excessive torque when using it, and it's gas and oil resistance makes it idea for applications like this.

Performance against plastic ?

[Destroyer]

Performance against plastic ?

No problems... only thing you need to be careful of is high heat (above 600Deg) So no exhaust fittings or the like.