Bad gas or a worse fuel system problem?

Hi and thanks in advance to anyone that can help. Got a 2000 Boomerang with about 290 hours. It's got the 350 w/ carb. On the way up north for the 4th I stopped at a little mom-and-pop gas station and topped it off with 91-octane. It had run beautifully all spring/summer before that tank (and since I bought it). The start-ups at the lake after that fill-up were more rough than usual, but the boat pulled skiers for the next two days so I thought little of it. Then, while pulling a skier at 30+ mph and without touching the throttle, the engine powered down to idle after I crossed a wake. The engine died after idling for about 20 seconds. I was able to start it up again, but once I put it in gear, it died again. That happened about 3 times until it finally wouldn't start at all and I got a tow - from the only other Moomba on the lake nonetheless! I didn't think it was a battery issue because it kept turning over just fine when I tried to start.

Trailered the boat home and actually found that a battery cable had loosened on the battery, so thought it had been shorting out on the bumps. Tightened that and cleaned up the terminal with fine sandpaper and it ran just fine in the driveway with the plunger attached for 15 minutes (even with a few revs above idle). Put it back in the water and it started perfectly. I skied one run just fine at about 35 mph. Killed same as above after 30 seconds of my second run. Got towed to landing and this time I replaced the screw-on fuel filter/water separator. I poured the contents of old filter into clear tupperware container and didn't see any water (but not exactly sure what I'd be looking for). There were a few black granules in it, but nothing that looked like it would totally clog a filter. Put it back in the water, started just fine so I warmed it up. After about 5 minutes of pretty hard driving and perfect performance (at near full throttle several times), it killed again same as above and again was towed back to landing. Haven't touched it since.

Every time it dies, it feels like the engine simply isn't getting enough fuel. My next plan was to drain the rest of the gas, but that seems pretty cumbersome, so I thought I'd see if anything else should be checked first. Thanks again!

Mine was having pretty bad fuel problems. I was looking into rebuilding my carb, and it took forever to locate a kit, all the while I would put a bottle of SEA FOAM every fill up. Problem has since worked itself out and runs wonderfully. Mine however has no inline filters, other than the ones that are in the fuel inlets of the carb. I will install an inline filter when I get the time.

Your problem does sound like bad gas. When I replaced the fuel inlet filters on mine I broke the fuel inlet lines (chrome) so I replaced them with one that has a fuel pressure gauge. I doubt it is your problem but you might have a fuel pump acting up.

If you put you pump your throttle lever then it should squirt gas at the top of the carb, this will help when starting.

Depending on the floats in your carb, one of them might be ruptured and filled with gas, thereby not working.

Carburetors are simple if you take time to learn about them.

My 1999 Mobius is doing the exact same thing! Have replaced carburator, fuel
Pump, filter, sea foam, gas treatments... I think It is vapor locking. Not sure tho. Runs fine for surfing and wakeboarding. I have run about 40 gals of premium gas thru it with no resolve. Help?!! Anyone! Thanks in advance!

My 98 had electronic ignition problems where I replaced the module twice in 10 years. It would sporadically cut in and out at different rpms and the last time I thought it was a carburetor issue. If you want to take the gas out it is easy as all you need to do is disconnect the hose at the carburetor and put it in a gas can and then jumper the fuel pump and it will drain rather quickly. The fuel pump could be an issue also and if it hasn't ever been replaced it would be time. The gas filter is a strange character as it is hard to tell when to replace it but a clogged filter would affect the engine more at high fuel flow (WOT) than at idle.

Now if I could get my hands on a replacement Airguide speedometer everything would be perfect.