The Mighty 258 > Fuel Systems.

I keep going through fuel caps!


When I got my bird I noticed the rubber seal on the locking fuel cap was cracked and it would not seal when I repaired the vent system. I can still get replacements so for $15 I swapped it out for a new one and things were fine again. Two years later though I started smelling gas again and found the rubber seal on the new cap was also now cracked up and split. I've put another new cap on but what's up with the fumes destroying the seals so quickly? Nowhere else in the fuel and vapor system have I found the same issue.

I've had a similar problem, I had to replace a gas cap to pass emissions, and the replacement cap, the rubber disintegrated.  I wonder if it has anything to do with the ethanol in the gas?

I have considered its the Ethanol. Nasty stuff but not a lot I can do about that.

Could be just cheap Chinese components.  Make sure the filler neck is smooth, too.  Though if it is made to 80's specs, it's probably not alcohol resistant.  Give it a light coat of dielectric grease, plumber's grease, Sil-Glyde, silicone spray, or anything else you have that's 100% silicone.  It acts like lotion for the rubber, keeping it soft and springy to prevent cracks and splits while repelling the alcohol-contaminated fuel.  And it's pretty inert, it won't damage the fuel system at all.  Also good for soft weatherstrip rubber such as that around the doors.

Think I'm gonna do that to mine this weekend...


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