help with odd carb problem

[Mouthfulloflake]

90 superjet, 650, pipe, head, msd nehancer... blah blah..

its always ran great.

the other day it was hard to start, I over primed it I think, it was really smoky and rich, then finally cleared out and was running ok ( on the trailer)

I went to launh it maybe an hour later, and it took forever to start in the water, finally started, but only if I held the throttle wide open, and it was barely pulling me, it started to clear out, and got better and better, and was finally rideable.

but it was very doggish, very rich, and I was constantly having to blirp the throttle to get it to rev, and it wasnt running 100%

I put it back on the trailer, and its smoking like hell, rich smoke, smells like gas.

I turned the fuel knob off, and for the last few seconds it was running ( as I blew the water out) it was running crisp and perfect again.

I have noticed the carb is spitting a little fuel out of the back cover sometimes.

is there something that can go bad, or clogg or something that will make it go really rich?

the mixtures screws are still in place, and dont appear to have been turned.

any ideas?

 

[Matt_E]

I suppose something could clog open the needle valve. I would pull that and inspect. If it's been a couple of years since it's been replaced, I would do that first.
Also check that the check valve(s) is/are not damaged.

 

[Idok]

maybe a leaky needle and seat??? could be dumping fuel down the carb throat and running really richy..

 

[Hogggman]

Check your primer line. I had the same prob with my X2 the seals in the primer plunger must have dried out or something and since the primer is tied into the fuel line it is always under pressure and will spit gas into the carb when the motor is running. I spent probably 6 months trying to get the jetting right on th X2 and as soon as i disconnected the primer it cleaned right up and ran beautiful

 

[Mouthfulloflake]

thanks for the ideas guys.

I will check it when I get home, my hood needs some additional mosquito fogging right about now anyway.

 

[Mouthfulloflake]

UPDATE.

I removed the carb today, dissasembled, cleaned out, reinstalled.

same problem.

there is fuel pouring out the orifices on the side of the carb, even with the engine off, so its WAY too rich.

i assume this means the needle and seat are leaking?

I didnt remove them, but I did verify the needle was freely moving, and sprayed carb cleaner thru it.

so can I just replace the needle and seat?

 

[Matt_E]

replace needle & seat...I am betting on that being the problem. Either needle or seat gets worn out, and then fuel leaks by. Order a new set, they cost about 20 bucks.

 

[Mouthfulloflake]

U just swapped carbs, stuck this jetting in another carb, problem solved.

:biggrin:

I pulled the needle and seat out, and they looked good, but it still leaked.

oh well.

back in action.

Thanks for the help!