What would suddenly cause a gas cap to swell?

common poulan malady.
Actually two common maladies: swelling caps, and hard starting when hot always.

caps are cheap, and the next one will swell also.


Old Yamaha motorcycles had the opposite issue: caps shrunk until they were smaller than the tank opening. at least there were aftermarket turned aluminum ones for those.

So the gas cap issue is a known Poulan problem? I've had my poulan pro for about 7 years now and just this summer noticed the cap was tough to get off and back on again. Weird.

I've seen plenty of Poulan/Craftman saws with the cap issues.

My Super 380 is 11 yrs old,gets used 3-4 hrs/week minimum year round.The 475 is 17 yrs old,dont get used near as much but I've had no such problems with either saw.

I read a recent post about Stihl string trimmers having the same problem...must be made by Poulan.

Even the most incompetent engineer wouldn't design a product that is defective on day 1, but it takes a really good engineer to foresee the easily unforeseen. This is pure speculation, but I would guess that the composition of the plastic in the cap reached some sort of inflection point where it started absorbing more ethanol, or had absorbed enough ethanol over a long period of time that caused it swell just enough to get stuck. This doesn't happen overnight. Or maybe it was stored with a full tank, on an angle, or whatever, such that the fuel was in direct contact with the gas cap, rather than just sitting below it.

Again, pure speculation.

They say if you have a spare you can cycle them and allow one to "dry out" once it gets too snug.

Hmmmm.......
this year all of my gas caps have become tighter
I blame the fuel additives
2 saws, blower and trimmer

"They say if you have a spare you can cycle them and allow one to “dry out†once it gets too snug. "

I'll find out. I installed a new cap 2 months ago and the old one has been inside on a shelf. When the new one begins to get too tight, I'll see if the old one is better and report back.

DanCorcoran said:

I read a recent post about Stihl string trimmers having the same problem...must be made by Poulan.

Click to expand...

See other thread

https://www.hearth.com/econtent/index.php/forums/viewthread/77705/P15/

it's the Ethanol they put in the gas now that is causing the caps to swell.
It's also wrecking havoc on the fuel lines, and diaphrams in the carburators....

I quit using it and make special trips just to get gas without ethanol.
I'm on borrowed time, and expect that one day we will not be able to get gas without ethanol.

your government at work.

James

"your government at work.

James "

Actually, your lobbyists at work influencing your political representatives. The government merely implements the laws that lobbyists and politicians concoct.

DanCorcoran said:

"your government at work.

James "

Actually, your lobbyists at work influencing your political representatives. The government merely implements the laws that lobbyists and politicians concoct.

Click to expand...

your right, but thats what I meant. The politicians make up the government.

James