FWIW. 2025 update. 1974 1.5F with DUI and Webber 38.
Just removed a Poly tank of indeterminate origin installed by PO in 2007.
I have had consistent problems with fuel delivery over the years, blowing out mechanical pumps, running out of gas, poor flow, and getting worse over time. Now can't accelerate without bucking/running out of fuel. I've mastered the "pull the fuel line and blow back into your tank to get the pickup off the bottom" routine. It ABSOLUTELY DOES collapse and block the pickup if you run it low. I have all breathers hooked up. No gas smell and no leakage - just inconsistent flow.
I pulled the tank last year and cleaned all, put new sender in... just kept having problems. Replaced rusty fill neck.
So, with ALL coming out, I've learned:
Poly tanks suck. literally. maybe new ones are different. They are MUCH smaller capacity, fuel guage will never work. No baffling. Collapsible. All fittings on top to prevent leaking.
Never use FIPG on poly tank, it WILL slough off and get everywhere. Wall of Shame action. Was trying to seal the sender. Thought I was careful.
PO used 1/4" lines... should be 5/16" from what I can tell. Think its like drinking through a swizzle stick especially if there are bits of FIPG in the lines, LOL. My mech pump could not overcome the need for lots of suction. I used a elect pump inline to help. I like the shop vac idea!
I may have been okay if I'd replaced soft lines and blown out the hard lines last year. Lesson learned.
The scorpion carcass wasn't there last year, LOL. pics won't load, will try later.
