NOPE; but I got to play with it for hours on end again last week and try an different patching approach. All for naught as it lasted 5 days this time (at least enough time to wheel and enjoy GSMTR without losing fuel).
This go around I completed:
patch on old used tank (used two part epoxy and fiber cloth) <sold as gas tank repair kit
(used low mileage) fuel sending unit (entire unit that bolts into tank)
NEW tank gaskets
NEW prefilter sock
NEW soft lines
NEW fuel filter (oem)
(used low mileage) charcoal canister
I plumbed a vaccuum guage to the vent line to the charcoal canister and it registered waaaaaaay low on the scale 7 kpH if i remember correctly. Can physically blow air through the vent line to the carcoal canister and as well from the charcoal return line back to the tank. No blockages. I t'd into the line right by the canister and ran it into the cab so I could monitor while driving. I have not tried running the guage at the return line, nor did I T in by the tank, but with the hard lines clear there should be no difference in pressure.
It almost appears as if the tank is collapsing or imploding due to vaccum. I only say this because of the shape and deformation at the crack.
After removal and repair, I waited 24 hrs to cure and filled up. NO problem. 6 days of highway and wheeling and no problem (3 fillups). First tank back at home and it starts to drip???
I fill up till it clicks off, no topping off, so it should not be overfilling and saturating carbon.
So as the vehicle uses fuel and the tank is emptied, what valve is responsible for letting air into the tank to prevent implosion? Is this the job of the gas cap as well?
7 kpH does not mean anything to me, got a reading in PSI? (PSIA, PSID, PSIG) or inches of murcury? (inHG)
you are reading a low pressure well below ambient on the gauge?
The gap cap has a small one way valve in it that will let air in as it is burned but this does not sound like vacuum from fuel use, I think your problem is direct manifold vacuum, you have a 300 cubic foot per minute, 212 horse power vacuum pump under the hood. if that vacuum is ported wrong and goes where it should not the differential pressure between outside the tank and inside will crush the tank,
there are two ways that I know of to get manifold vacuum to the fuel tank,
1 incorrect plumbing, a simple misplaced vacuum line or vent line mis-routed could do this, most likely somewhere around the left side of the engine and left inner fender,
2 malfunctions of the purge cycle of the charcoal canister, the purge valve occasionally ports manifold vacuum to the canister, air flows into the charcoal canister from a vent in the bottom preventing vacuum exposure to the tank, if the vent at the bottom of the canister is plugged the tank would be vacuumed down,
Blowing into the canister is not a good test, you could be blowing through the canister, purge valve and into the manifold, an open path with the engine off, not so much when it is running,
Didn't look like ether had anything significant in them. Blew them with compressed air and reinstalled.
