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[Tom Wesenberg]

Have you removed the fuel line at the carb and let it flow into a quart jar?
You should have a strong steady flow until the jar is almost full.

[sgwilson904]

Originally Posted by Tom Wesenberg

Have you removed the fuel line at the carb and let it flow into a quart jar?
You should have a strong steady flow until the jar is almost full.

Yes, at first thinking it was debris in the fuel line (we saw a very few flakes in the glass bowl at the firewall), we drained the tank entirely. Nothing much came out of the tank when we drained at the fuel shutoff valve.

Suspecting the flakes were tiny pieces of cork from the gas guage, we replaced old one with a new neoprene one to prevent any future cork erosion due to ethanol. We also replaced the filters at the tank shutoff valve, thoroughly cleaned the glass bowl and replaced filter in there, replaced fuel line itself, then checked flow which was fine. Also checked to see that fuel line was properly inserted at the firewall and at the carb.

After all that, it ran fine for a while (as in maybe 10 minutes), then started sputtering and backfiring and losing power again.