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Post by 180°off on Feb 10, 2017 15:20:10 GMT -5
Ok thought I had it fixed, but was wrong! Sometimes after I shut off my scoot gas starts leaking out the intake. Tried 3 different fuel pumps and went with what I thought was working. Is there any way that after shut off that vacuum could still be keeping the pump open? Or needle is bad? I adjusted the needle, no help. Or could there be something else that I'm missing?
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Post by FrankenMech on Feb 12, 2017 1:36:32 GMT -5
Fuel PUMPS???
Is your fuel tank above or below the carb?
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Post by 180°off on Feb 12, 2017 2:52:38 GMT -5
Tank is above the carb. I set and reset the float. Keeps leaking. Used a fuel pump hoping it would help stop the leak. No luck. Have a petcock now but if I forget to close it I dont want to run out of fuel. What else? I have tried new needle valves. 2 floats. Adjusted floats. What am I missing or doing wrong?
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Post by RustyPop on Feb 12, 2017 5:07:21 GMT -5
Have you checked the drain screw ?
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Post by 180°off on Feb 12, 2017 9:33:30 GMT -5
Yes checked drain screw
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Post by oakleyscoot on Feb 12, 2017 11:01:34 GMT -5
Fuel flooding the carb or leaking out of the carb when the engine is not running can only happen a few ways.
If there is pressure in the fuel system that can FORCE fuel to upset the needle and seat and let fuel by or
the float level is too high thus allowing too much fuel into the float bowl, but usually if this is the case
you will find too much fuel even with engine running,
The other way is the needle simply is not sealing in the seat. Careful inspection of the needle tip may show
signs of pitting or other signs that it is not in acceptable condition, also careful inspection of the seat
may very well show signs that the needle is not completely seating.
sometimes one can polish the seat with something like spinning a Q-Tip with a touch of metal polish in the seat this may allow a better seating of the needle. NOTE: this will probably work best if your needle has a rubber tip, if its all metal it may not help at all but its worth a try.
My .02¢
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Post by gsx600racer on Feb 12, 2017 13:23:30 GMT -5
Lets first establish what the difference between a fuel petcock and fuel pump. Fuel petcock These devices act as a valve and only allow fuel to flow when the engine is running.   Fuel pump These pump fuel from the tank to the carburetor if the fuel tank is lower than the carburetor. The might look like the petcocks, but they are larger in size.   I doubt its a fuel pump issue if the tank is higher than the carb. There might be a problem petcock. Either the seat in the petcock is dirty or worn and not closing or the diaphragm has failed and allowing fuel to pass by and end up in intake. Having clear(see thru) lines or just pulling the hoses off the carb and manifold and see where the fuel is coming from. Also the float in the carb is set to high or the needle/seat is worn and leaking. |
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Post by FrankenMech on Feb 12, 2017 13:46:26 GMT -5
WTF!
A scoot fuel PUMP has check valves that will allow fuel to run right through it one way (out). Never use a fuel PUMP to try to stop fuel flow.
Some carb needle valves and/or passages are bad, nicked, misaligned, not concentric, etc, and will leak fuel. That is why the OEM manufacturers include a petcock, either vacuum or mechanical, for a secondary seal in gravity feed fuel systems.
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Post by 180°off on Feb 13, 2017 20:55:48 GMT -5
Ok, I guess I confused the petcock and pump a little bit. I'm guessing the needle isn't sealing right. I set and reset and reset the needle. Also I'm running unrestricted air filter. I put in the largest jet I have because it seemed to work best. Its a 145 jet I dont think there is any bigger.it boggs at full throttle? Tried almost everything. I'm missing something. Maybe get rid of fuel pump? Since needle maybe bad that is effecting wot? Remember its a 150.
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Post by FrankenMech on Feb 13, 2017 22:31:05 GMT -5
Get rid of the pump. Get a manual petcock for K.I.S.S.
A fuel pump will add pressure to the gravity pressure on the needle and will affect the float level a little.
The needle shutoff is rarely 100%, most will weep a little but that is insignificant. A leaking needle makes very little difference at idle and none at speed. The needle and seat is very delicate and easily damaged, but again the leakage is slight and usually insignificant during operation.
Cover part of the air filter and make a test run. If that makes it worse or better you know which way to go.
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