Gas pouring from carb

[SaltyBones]

Recently rebuilt my carb and started the ski. Noticed a very significant drip coming from under the carborator. Turned it off and covered it up. Haven't had a chance to dig any further. It was almost like it had a float set waaay too high, but there's no float in the carb.
Also, I don't think there's anything blocking the return line, but I've not checked. What do you guys think is going on here?

 

[jhjesse]

Gas tank vent not working and creating excessive pressure that overcomes the needle and seat bleeding gas into the engine.

Pop off pressure could be too low allowing fuel to pass through the needle and seat easily when pressure builds in the gas tank.

 

[Sportster-2001-951C-Stock]

Fuel line leaking at hose nipple most likely?

Doubt there's a hole in fuel chamber metering diaphragm but it's possible perhaps.

Or, if on fuel feed side the pretzel o-ring but it should fail pop test in this case.

Have a great weekend.

 

[SaltyBones]

Fuel line leaking at hose nipple most likely?

Doubt there's a hole in fuel chamber metering diaphragm but it's possible perhaps.

Or, if on fuel feed side the pretzel o-ring but it should fail pop test in this case.

Have a great weekend.

What are speaking of specifically regarding the pretzel o ring

 

[warriorde52]

The funny looking o ring on the side of the carb with the filter.

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[RodInEscondido]

What was pop-off? Needle valve lever could be set too high preventing needle from seating properly.

 

[SaltyBones]

Been busy & not able to mess with the ski. Anyway, The fuel appears to be coming out the top like a float set to high.

 

[SaltyBones]

Just to add...it starts up and runs seemingly fine for the couple seconds I let it run. Just from what I can tell it overflows somehow.

 

[chris1994eg]

have the same problem.. and runs like shyt... contacted nick from westcoastpowersports and he sudjested using OEM mikuni carb kit needles and seats.. waiting on them and will let you know how it goes. btw.. i had used some aftermarket carb kit and needles and lasted about 2 weeks before it started running like crap and always had a small leak on the carb.

 

[Sportster-2001-951C-Stock]

Been busy & not able to mess with the ski. Anyway, The fuel appears to be coming out the top like a float set to high.

If the fuel seems to be coming from the carburetor bore than I would agree this seems to suggest the metering needle is not sealing on it's seat, or the o-ring that seals around the OD of the seat is leaking.

If you can reach the fuel line nipples, you can do an on-motor pop leak check, it should not immediately leak down but if it does and there are no external leaks on the filter side cover this confirms an issue with the metering needle and seat.

If the needle's rubber tip is worn, grooved, ripped or torn, it must be replaced.

Can't go wrong with authentic Mikuni parts, best dressed for success.

 

[SaltyBones]

If the fuel seems to be coming from the carburetor bore than I would agree this seems to suggest the metering needle is not sealing on it's seat, or the o-ring that seals around the OD of the seat is leaking.

If you can reach the fuel line nipples, you can do an on-motor pop leak check, it should not immediately leak down but if it does and there are no external leaks on the filter side cover this confirms an issue with the metering needle and seat.

If the needle's rubber tip is worn, grooved, ripped or torn, it must be replaced.

Can't go wrong with authentic Mikuni parts, best dressed for success.

Just to be clear w/the on motor pop off test...I disconnect at the feed/fuel in and leave everything else connected...right?

If so, it failed that badly

 

[SaltyBones]

The forum will not allow me to post pics right now for some reason, but I took the carb apart where the pretzel o-ring is. the o ring is fine, but there's a very thin, large, black, rubbery gasket looking thing that was crinkled up on the ends. It is part # 270500103 and i'm guessing since its crinkled up on the ends that it is the reason fuel is overflowing. Thoughts?

 

[Sportster-2001-951C-Stock]

That gasket would be on the fuel feed side of the carburetor. It's not unusual for the rubber gaskets, diaphragms and o-rings to absorb some fuel and swell a bit, then they look funny when the carb is first disassembled but once dry and the fuel has evaporated, return to their original shape.

If the fuel was leaking from the bore, where the throttle butterfly is, this tells you the metering needle was not sealing in the seat, or fuel was leaking from around the outside of the seat, past that pencil diameter round o-ring.

But remember, when pressurizing to test pop and/or a metering needle leak problem, you must block off the fuel return line. You can simply pressurize the fuel pump inlet line while the return line is blocked off and should be able to build at least 20psi of pressure before one of the needles pops off the seat.

If not, and the fuel return line was blocked off as it should, there's definitely a leak somewhere, quite possibly the needle isn't sealing into the seat, if the fuel gushes from inside the bore.

If the leak is external to the bore, for instance coming from the side cover, the metering needle isn't the cause. In this case, there's some kind of problem with the cover gasket.

BTW, I'm not sure which type of carbs you have, I'm guessing you have two mounted and the fuel pump is on the PTO carburetor.

This gasket you mentioned, doesn't need to be installed on the carb that doesn't have a fuel pump, just the pretzel o-ring is sufficient.

But if you're like me, I prefer to put all the gaskets, o-rings and seals back in the same configuration as the factory did, assuming someone before me hasn't goofed it up already then I have to figure out if they made a mistake and correct it.

If the offending carb in this case is the one that doesn't have the fuel pump, you don't need that gasket, just the pretzel o-ring is sufficient.

The carb shown in this drawing does have the fuel pump, and that gasket is item #5 The other carb, without the fuel pump just has the cover and pretzel o-ring.

Again, don't forget when testing the metering needle/seat you must block off the fuel return line.

Good luck, let us know if you get it.

 

[SaltyBones]

Replaced the gasket since I'd already ordered it and seems to run great on hose with no signs of leak. Glad I didn't have to buy a whole kit.
Anyway, when its running, there seems to be excess smoke out the back (on the hose). I'm guessing I must have messed up the oil pump setting on that cable when I put it back on the carb.
Any tips on adjusting the oil pump other than just loosening that bolt thing at the carb? Any specific way or number of turns?

 

[mikidymac]

They will smoke some when cold and on the hose. This is very normal. The only way to set the oil pump is to align the marks and adjust with the cable end bolt on the carb. Use a mirror for the 720.

 

[Sportster-2001-951C-Stock]

Make sure the pump lever is rotating as you operate the throttle. At idle position the (sometimes faint) marks on the pump body and the pump lever should be in alignment so check/readjust each time after the carb idle has been adjusted. Adjust cable tension as necessary.

The alignment marks in this photo are circled in red, this is 787 but alignment is similar not exactly the same pump and direction I'm not sure just showing the alignment marks location.