Pounding banks Loc: South Central Texas

easier said than done, couldn't break the jam nut loose to unscrew the fuel pickup fitting

Fredfish Loc: Prospect CT.

Aluminum fittings can be a pain in the azz.
The only alternative is to remove the sending unit and float. Then you can try and fish the pickup tube over to the bigger hole with an piece of wire or coathanger.
Before that, try blowing into the fuel fitting, if its very hard to blow either the pickup is clogged or the vent tube is blocked. Crack the gas cap open and try again. If it's easier, then the vent is blocked, if not its the pickup.

Fredfish Loc: Prospect CT.

If this is too much work, to get at everything, hookup a portable fuel tank and see how it runs on that. If it's ok, then your tank is the problem, if not then your tank is OK.

Barnacles Loc: Northern California

Try this: When the engine starts to bog down look at the engine's pee stream. If you see a lot of steam or no pee stream, you're overheating. If you don't see a problem there, squeeze your primer bulb. If the engine starts to recover and gain strength, it's a fuel feed issue. You mentioned already replacing fuel hoses, filters, etc. but maybe a kink in a hose somewhere? Another place to look is under the cowling. Often, people replace all the filters, hoses, etc. between the tank and the engine, but the problem can be in the fuel path inside the cowl. The engine is trying to suck fuel up from the tank, but any leak will pull in air. If a hose feels hard, replace it. Finally, disconnect a fuel line where it connects to the carburetor and put the end in a container. Squeeze the primer bulb several times. Does fuel pump well, or does it take some force on the primer bulb to get a good flow? Are there bubbles coming out with the gas? That would indicate air being sucked in somewhere between the fuel in the tank and the primer bulb. Lastly, plug the end of the hose and squeeze the bulb again. Does fuel leak out anywhere between the bulb and the carburetor-end of the hose?

fishyaker Loc: NW Michigan (Lower Peninsula)

Great idea there Fredfish regarding the switch out of a portable test tank!

fishyaker Loc: NW Michigan (Lower Peninsula)

Ah yes...Seafoam...the "wonder drug" of modern engines! I run that stuff thru anything I own with a motor...including my vehicles. That product works wonders when used on a fairly routine basis...and also to potentially help cure a problem such as this one.

I save my small cans to re-fill via the one gallon sized container that some auto parts stores carry. A buddy of mine buys it in large drums!

Even if this is not the issue, it would not be a bad idea to consider using it! I think many here on the Stage will vouch for it's overall helpful properties....

Another good idea TexasWomack!

Fredfish Loc: Prospect CT.

It's probably the easiest thing to do if you have access to one, Yaker.

DozerDave Loc: Port Orchard Wa.

Seafoam is nothing more than diesel fuel, cleaning solvent and alcohol. You can make it yourself. It’s 4 parts diesel 2 parts solvent 1 part alcohol… 🐟on

Gordon Loc: Charleston South Carolina

Sometimes dirt daubers will plug up the vent line.

TexasWomack Loc: Prosper, TX

I’m all about solving issues and Seafoam is some amazing stuff.

Grizzly 17 Loc: South central Pa

Yaker I have a 15hp merc Bigfoot on my glastron. I left it sit for at least 2 yrs.
Decided to get it out last yr. It started easy enough but would stall out. I was told about seafoam n put it in.
Got it out fired her up. When she'd start to stall I'd bump the choke.
After a few timesshe would idle well.
Took her to the lake n by end of day she was running real nice. 👍

Grizzly 17 Loc: South central Pa

Dave that sounds like some of the stuff I use to drink 🤔

ricky risteen

Stop throwing parts at this motor!! Check compression, check spark, check your for any water in the fuel.You may have to remove a plug on carb to sea if any water is presend. also the same for EFI. Rule of thumb on compression, If there is 10 15 percent difference between cyls you have ring sealing issues. You are also looking for real blue spark and continuous with out any drop outs. Ricky Sitka

Bigbum Loc: Washington

Had that problem in my 19’
Changed filters etc
Tried adding a couple containers of Heet water displacement
OMG what a difference
Cleared it right up
Now I add a bottle every couple tanks and a couple at winter storage
Couldn’t believe what an easy fix
Good luck

Whitey Loc: Southeast ohio

I like Berryman B12 chemtool Clean's carburetors up nice. All good advice 👍. Good luck PB 👍