Carb leaking fuel
08-20-2009 | 06:29 PM
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From: Sudbury,
ON, CANADA
Carb leaking fuel
Hey guys, i just finished up my engine stand, mounted the engine on it then went to go start it and i noticed when i primed the engine and then create compression i have fuel leaking from my carburator, specifically where the choke is. I have a Magnum RFS 70, i got it started but do not have the leak problem figured out. The engine is mounted up right if thats any help. What is my problem ? am i doing something wrong ? Is is normal ?
Thanks
Thanks
08-20-2009 | 07:41 PM
#2
RE: Carb leaking fuel
How high is the fuel tank in relation to the needle on the carb? Most times it is ideal to have it below the needle, but difficult to do with a test stand. If the tank is high, this is normal and nothing to worry about once mounted in a real plane.
Curtis
Curtis
08-20-2009 | 09:43 PM
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RE: Carb leaking fuel
right now with the stand, the tank sits up a couple inches higher than the needle, and in the airplane the ideal place would be the half = needle of carb ?
thanks
thanks
08-21-2009 | 01:52 AM
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RE: Carb leaking fuel
ORIGINAL: Seb23
right now with the stand, the tank sits up a couple inches higher than the needle, and in the airplane the ideal place would be the half = needle of carb ?
thanks
right now with the stand, the tank sits up a couple inches higher than the needle, and in the airplane the ideal place would be the half = needle of carb ?
thanks
Your carb is not leaking your are flooding it with an excessively high tank mounting. It makes no differance the tank center to spraybar (needle valve) relationship needs to remain the same: mounted in the stand, the airplane, upside down, sideways or upright.
The tank centerline level with the Spray bar (needle valve) or just slightly lower is the ideal relationship.
John
08-21-2009 | 04:05 AM
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From: Wellington, SOUTH AFRICA
RE: Carb leaking fuel
ORIGINAL: Seb23
Hey guys, i just finished up my engine stand, mounted the engine on it then went to go start it and i noticed when i primed the engine and then create compression i have fuel leaking from my carburator, specifically where the choke is. I have a Magnum RFS 70, i got it started but do not have the leak problem figured out. The engine is mounted up right if thats any help. What is my problem ? am i doing something wrong ? Is is normal ?
Thanks
Hey guys, i just finished up my engine stand, mounted the engine on it then went to go start it and i noticed when i primed the engine and then create compression i have fuel leaking from my carburator, specifically where the choke is. I have a Magnum RFS 70, i got it started but do not have the leak problem figured out. The engine is mounted up right if thats any help. What is my problem ? am i doing something wrong ? Is is normal ?
Thanks
If so, it is normal as far as I know. When priming you are "pumping" fuel into your intake for cold starting (well this is what I think it does and how I understand it
)This will then result in fuel coming out of the carb.
08-21-2009 | 05:25 AM
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From: Lacona, NY
RE: Carb leaking fuel
ORIGINAL: JohnBuckner
Your carb is not leaking your are flooding it with an excessively high tank mounting. It makes no differance the tank center to spraybar (needle valve) relationship needs to remain the same: mounted in the stand, the airplane, upside down, sideways or upright.
The tank centerline level with the Spray bar (needle valve) or just slightly lower is the ideal relationship.
John
ORIGINAL: Seb23
right now with the stand, the tank sits up a couple inches higher than the needle, and in the airplane the ideal place would be the half = needle of carb ?
thanks
right now with the stand, the tank sits up a couple inches higher than the needle, and in the airplane the ideal place would be the half = needle of carb ?
thanks
Your carb is not leaking your are flooding it with an excessively high tank mounting. It makes no differance the tank center to spraybar (needle valve) relationship needs to remain the same: mounted in the stand, the airplane, upside down, sideways or upright.
The tank centerline level with the Spray bar (needle valve) or just slightly lower is the ideal relationship.
John
Your right... I too usually try to have my glow tank centerline level slightly lower, or even with the Needle Valve. It's even more critical if I plan to have my 2-stroke inverted. So I second John's answer.
Pete
08-21-2009 | 07:13 AM
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From: Sudbury,
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RE: Carb leaking fuel
yeah well after priming, i release the choke leaver and the fuel i has primed kind of all fall's out ... im sure some goes in the intake because when i do the compression exercise all is fine, what was happening is fuel was being siphoned into the carb, therefore leaking out automatically, i was sure fuel had to be higher than the carb 
I will try again today and let you know of the results
I will try again today and let you know of the results
08-21-2009 | 04:40 PM
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From: Sudbury,
ON, CANADA
RE: Carb leaking fuel
since its already pushing fuel in the engine. i got it going for a good 6 mins today at work so everything seems good, but i was just curious about the leaking carb. How much of leakage should an average engine have ?
thanks
thanks
08-21-2009 | 04:46 PM
#10
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RE: Carb leaking fuel
ORIGINAL: Seb23
what was happening is fuel was being siphoned into the carb, therefore leaking out automatically, i was sure fuel had to be higher than the carb
I will try again today and let you know of the results
what was happening is fuel was being siphoned into the carb, therefore leaking out automatically, i was sure fuel had to be higher than the carb
I will try again today and let you know of the results
Of course it is syphoning with the tank so high. It is a test stand fix it, lower the tank. continued runing on the stand without positioning the tank/spray bar (needle) relationship will serve no purpose.
08-22-2009 | 08:51 AM
#11
RE: Carb leaking fuel
Remember that nipple on the muffler that you connected to the tank? That pressurizes the tank and pushes the fuel to the needle, so you don't need the tank above the needle.
