fuel problem

[tompowers85]

I have a 1975 merc 850 with WMK-17 carbs on it. I have rebuilt both carbs cleaned everything. I tuned the floats to manual specs. If the engine is cold and not running i can prime the bulb and it will stay hard for along time. Once i put the motor in my test tank and fire it up after aboat 10 minutes the balb will drain and the engine will stall. When I attempt to prime the bulb again gas starts spraying from the vent on top of the carburator (top carb mostly). I have also rebuilt the fuel pump and checked the valves. I can not find any leaks in the fuel line. Please help it is driving me crazy!!!

 

[Smig]

Re: fuel problem

Bad bulb or closed vent on tank can cause the bulb to collapse.

 

[Silvertip]

Re: fuel problem

If squeezing the primer bulb causes fuel to run out of a carb, either the float is not installed properly, not adjusted properly, or the inlet needle and seat are not sealing properly. A float that is hanging up will also cause the problem. That would also account for the fact the bulb will not firm up again -- the float is not shutting off the flow. The engine is stalling due to being flooded, not running out of fuel. A primer bulb will not stay firm once the engine starts. That's because fuel is being "drawn" through it. There is no pressure in that part of the system.

 

[tompowers85]

Re: fuel problem

i closed the needle valves and was unable to blow air through the hole. The metal tabs that closes the valve are supposed to be level when the top piece of the bowl is upside down. Should I adjust that to close the valve when the bowl has less fuel. It will shut the valve sooner causing the float not to rise as high.

 

[johnnyz48]

Re: fuel problem

Stick with the recomended float level. Thats my opinion. I'm only a cadet here but your carb will work best when it is adjusted to specs

 

[Chris1956]

Re: fuel problem

Tom, Are the little springs on top of the carbs in good shape? Are the floats saturated with fuel or cracked? The original floats were foam. Replacements are hard plastic.

 

[tompowers85]

Re: fuel problem

The floats are new one i just replaced the other maybe a year ago. The springs on the top of the floats are fine.