Plug Fouling

[renodaytona]

So during the trip down for the Big Cat poker run the Eliminator Ski comp developed an issue. After running around all day we idled into Discovery bay in the afternoon all the way to the marina, we sat there for a bit and jumped in to cool off. We idled back out to head back to Windmill and couldn't get the boat over 2000/2500 rpm. Limped it all the way back to windmill to get it on the trailer. Got home and pulled all of the plugs. 6 of 8 show very rich condition 2 were fouled completely (re-jetting will take place after I figure out what's happening). Fast forward after new plugs and checking over the carb (on the boat) went to Frenchman's to "test" and enjoy the afternoon, boat ran perfect all afternoon. Decided to take one more dip before heading to put the boat on the trailer and bam again the boat is acting the same as before, stumbling over 2000/2500 RPM. Haven't pulled the plugs yet (been busy with my daughters soccer) pulled the fuel filter and blew through it (no blockage). Next step is pulling the carb to go through it.

Possibly something stuck in the float needle or possibly the floats are somehow out of whack? This motor sits angled to the rear in the boat (direct drive) and this is a new issue that just surfaced. It has run amazing for two summers after all the things I have upgraded and re-wired until the last two trips.

Current set-up FST 4150 carb, mechanical fuel pump, post tank/pre pump filter.

 

[obnoxious001]

I am not aware of FST carbs (I did look up their website). Fuel filter problem would likely make it run lean, so yes, I would open up the carb and have a look. Other thing would be if there were too much fuel pressure for some reason. It's not doing your rings and cylinders any favors when it does that.

 

[renodaytona]

I am not aware of FST carbs (I did look up their website). Fuel filter problem would likely make it run lean, so yes, I would open up the carb and have a look. Other thing would be if there were too much fuel pressure for some reason. It's not doing your rings and cylinders any favors when it does that.

Standard mechanical pump at 8lbs with gage at the fuel inlet splitter to the bowls. This is on a Indmar 454, fresh oil change, so I will check that and see if I'm washing down cylinders.

 

[Spray-N-Sand]

Renodaytona, is your carb jetted for the high altitude? Delta’s @ sea level.

 

[renodaytona]

I’ve run it up here 4000 ft elevation for two summers, ran it in Havasu for 4 days with zero issues. This started after the long idle into discovery bay.

 

[renodaytona]

So I did some research on the FST carbs (haven't pulled it yet) there seems to be an issue with the floats cracking on them. If that's the case with mine this would explain the possible issue. I will report back tonight after I pull the carb off and apart.

 

[renodaytona]

Found the issue. The bowls are coated and the coating is flaking off. There were several pieces in the needle. Time for some oven cleaner to strip the insides. Poor choice by FST to coat the insides of the bowls.

 

[mattyc]

Found the issue. The bowls are coated and the coating is flaking off. There were several pieces in the needle. Time for some oven cleaner to strip the insides. Poor choice by FST to coat the insides of the bowls.

View attachment 1417791

View attachment 1417792 View attachment 1417793

That's lame. Does the rest of the carburetor have the same coating? Any idea what it is?

 

[renodaytona]

That's lame. Does the rest of the carburetor have the same coating? Any idea what it is?

Looked like anodize but now that I’m stripping it off with aircraft stripper it’s powder coat.

Here is a flake sitting on the needle seat assembly.

 

[mattyc]

Looked like anodize but now that I’m stripping it off with aircraft stripper it’s powder coat.

Here is a flake sitting on the needle seat assembly.

View attachment 1417800

Are you stripping the whole bowl or just the inside?

 

[renodaytona]

Just the inside. Ended up getting the table top sand blaster I got a while back all set up. Finishing blasting them this morning.

 

[renodaytona]

Got them blasted and carb is back together going to put it on, replace plugs and fuel filter and should be good to go.