Boat Fouling Plugs Non-Stop

[Gondon]

99 speedster 787

Hey Guys, not sure what’s going on. I ran fine last week for a few hours. I parked the boat and came to take a ride today. Both engines sounded terrible and wouldn’t move past 4K.

I changed the plugs. The boat ran perfect for the next 2 minutes at 50 mph. I slowed down to idle, tried to give it gas and that’s it..all the plugs fouled again. What is happening? This is beyond frustrating at this point.

Recently had new fuel pump, fuel filter and carbs done. Thx

Thank You

 

[mikidymac]

If it is fouling plugs that fast I would look at leaking needle and seats or crank seals.

 

[JeremyD615]

Are you sure the plugs are actually fouled? I just had a similar issue and it was a massive exhaust leak in the bilge. It would run fine for a couple of minutes until the hull filled back up with fumes and then would go pig rich as it couldn’t pull any more fresh air. I’m assuming that’s a rare occurrence, but it’s something to check while you’re in there looking at carbs.

 

[Gondon]

If it is fouling plugs that fast I would look at leaking needle and seats or crank seals.

Needle and sears? Are those carbs?

 

[Gondon]

Are you sure the plugs are actually fouled? I just had a similar issue and it was a massive exhaust leak in the bilge. It would run fine for a couple of minutes until the hull filled back up with fumes and then would go pig rich as it couldn’t pull any more fresh air. I’m assuming that’s a rare occurrence, but it’s something to check while you’re in there looking at carbs.

Yea, they are black and covered in oil! Hmm I mean I do smell a shit ton of gas when I open the engine bay.

 

[mikidymac]

The needle and seat are in the carbs and control how much fuel goes into the carbs. IF they are leaking it will flood the engine and run rich.

If you smell fuel in the engine bay you better get it fixed ASAP! This can and will cause an explosion destroying the boat and injuring you or your family. This is not something to mess with.

 

[JeremyD615]

Yeah, you shouldn’t smell gas at all! My ex wife was seriously burned when she was young in a boat explosion caused by a fuel leak and using an automotive starter. Definitely not to be messed with! Mine didn’t smell like gas in the bilge, it smelled like oil and exhaust fumes, and it wasn’t even enough to notice unless you had the cowl and tray open. Still, after getting that leak I’m going to pay much more attention to how long I run the blower before cranking the ignition...

 

[Gondon]

The needle and seat are in the carbs and control how much fuel goes into the carbs. IF they are leaking it will flood the engine and run rich.

If you smell fuel in the engine bay you better get it fixed ASAP! This can and will cause an explosion destroying the boat and injuring you or your family. This is not something to mess with.

God Damn! I ran the fan for 5 minutes.

Hmm, that’s interesting as I justness had a shop do the carbs?

Eeek, when I ran the bilge pump last time I noticed dirt come out but fuel as well because the water had those fuel/oil ring stains coming out.

Yea, def not starting it up now...
Not sure if that’s rain water but after bilge it drained out.

 

[Gondon]

Yeah, you shouldn’t smell gas at all! My ex wife was seriously burned when she was young in a boat explosion caused by a fuel leak and using an automotive starter. Definitely not to be messed with! Mine didn’t smell like gas in the bilge, it smelled like oil and exhaust fumes, and it wasn’t even enough to notice unless you had the cowl and tray open. Still, after getting that leak I’m going to pay much more attention to how long I run the blower before cranking the ignition...

Now I’m scared..it’s def oil and exhaust fumes smell..

 

[JeremyD615]

That’s definitely rich! You’ve only run it twice since the carbs were done? Do you know what the adjustment screws are set at now?

 

[mikidymac]

Those plugs are super rich. I am going to say leaking needle and seat and the shop probably did not use Genuine Mikuni parts. I would be taking it back to them and asking WTF!

 

[Gondon]

That’s definitely rich! You’ve only run it twice since the carbs were done? Do you know what the adjustment screws are set at now?

No clue, probably 3-4 times but each time I had to change the plugs shortly after or mid ride. But now I couldn’t even get on full throttle and idle. Went through 2 sets of plugs yesterday. I tried again after this post. Ran for 1/4 mike put the idle and that was it..limped back to the dock to pull those out.

 

[mikidymac]

Not sure why you keep trying to drive it, it isn't going to fix itself.

 

[Gondon]

Those plugs are super rich. I am going to say leaking needle and seat and the shop probably did not use Genuine Mikuni parts. I would be taking it back to them and asking WTF!

Arghhh! I’ll keep you guys posted. I feel like sinking the boat at this point. Very frustrated.

 

[Gondon]

Not sure why you keep trying to drive it, it isn't going to fix itself.

I meant yesterday while I was still in DIY diagnose mode after post 1#. Now it’s just sitting with a cover

 

[JeremyD615]

Mikidymac is right, I’d be taking it back to the shop and having them pull the carbs back off. In the future, I’d recommend finding a good shop manual and investing in a pop off tester so that you can do your own carb work. It’s not nearly as difficult as you would think, and it gives you a lot of peace of mind knowing that your settings are correct.

 

[Gondon]

So what’s the consensus is it safe for me to even start the boat? I might just have the mechanic come get the boat himself, it’s literally down the street from me.

 

[JeremyD615]

Are you just trying to put it on the trailer, or drive the boat to the marina? I wouldn’t be too scared to put it on the trailer, but open the hatch and check for fumes before you start it for sure!

 

[Gondon]

Neither at this point haha! Boat is frustrating me.

 

[mikidymac]

Neither at this point haha! Boat is frustrating me.

Then there is no point in trying to start it just to see if it starts. Fix the problem.

 

[Gondon]

Then there is no point in trying to start it just to see if it starts. Fix the problem.

Waiting to hear back from mechanic

 

[Gondon]

Still waiting to hear back..I just realized and I wonder if this is normal every time I start the boat blue smoke and just tons of smoke is coming out from the back of the engine bay.. first few minutes the engine is started and I’m sitting at the dock. Once I leave the dock and accelerate away it goes away...the mechanic and seller of the boat told me this is normal and the engine burning oil that’s how 2 strokes work.

 

[JeremyD615]

Some smoke is normal from the exhaust, but it shouldn’t be in the engine bay. I think of white smoke when I think two stroke, but I guess it would have a bit of a blue tint if it was burning quite a bit of oil. Make sure when your mechanic puts the carbs back on that he’s aligning the oil pump arm with the housing. You may be rich in your oil setting as well.

 

[Gondon]

Some smoke is normal from the exhaust, but it shouldn’t be in the engine bay. I think of white smoke when I think two stroke, but I guess it would have a bit of a blue tint if it was burning quite a bit of oil. Make sure when your mechanic puts the carbs back on that he’s aligning the oil pump arm with the housing. You may be rich in your oil setting as well.

Some smoke is normal from the exhaust, but it shouldn’t be in the engine bay. I think of white smoke when I think two stroke, but I guess it would have a bit of a blue tint if it was burning quite a bit of oil. Make sure when your mechanic puts the carbs back on that he’s aligning the oil pump arm with the housing. You may be rich in your oil setting as well.

Thanks, yea I meant the exhaust bay.
Prettty sure it’s the carbs after doing more research as you guys suggested with the settings and all.

 

[JeremyD615]

I think you’ve got more than settings issues. It sounds to me like you’ve got aftermarket carb kits installed, and they just don’t seem to work well at all. Have them rebuilt with the proper Mikuni kits and OEM needles and seats and that should solve your bogging issue. I’d still be searching for the source of that fuel smell though...