Walbro WMA 3 carburetor: float drop question.

[Fishsqueezer]

I?m using the Mercury service manual for my engine (Mariner 50 hp, 4 cyl, 2 stroke, electric start, SN. 6542853), but I?m still having a few issues.

I installed a new white plastic float which only has one metal adjustment tab for float level, but no way to adjust drop. I?ve been able to get the float level correct by bending the metal tab which contacts the inlet needle spring, but float drop is not on target. The book advises installing a new float if drop is not correct since the white plastic floats are not adjustable in both directions. However, this float is new, yet it does not drop all the way! The float bottoms out against the carb body at a distance of 3/32? from the main jet. The factory manual specifies a distance of 1/32? to 1/16? between float bottom and main jet. What should or can I do about this issue? Is this a big problem? I know carbs are very finicky.

Anyone have wisdom on this issue?

 

[SparkieBoat]

Re: Walbro WMA 3 carburetor: float drop question.

I do not think 1/32 is a big issue with the float...give it a try and see how it runs..probably ok. I have never checked my floats for drop. the place where it closes the needle valve is the most important, so long as you are getting a full flow of fuel, I cannot image 1/32 would make a difference. actually carbs are not very finiky, just need to be clean and adjusted somewhere close and they really get the job done..one of the greatest inventions of man and now its being outlawed..frikin pisses me off.

 

[aussieflash]

Re: Walbro WMA 3 carburetor: float drop question.

Not sure your reading it properly.As sparky said needle valve closing/opening is the issue.My float level is measured by turning bowl upside down and then measuring float drop from bowl surface.My spec is also to 1/16".So turn bowl UPSIDE DOWN.

 

[Fishsqueezer]

Re: Walbro WMA 3 carburetor: float drop question.

Thanks for the info. I'm learning slowly but surely, but still having problems.

This all began a few weeks ago when fuel squirted out of the vent hole on my upper carb. Inspection revealed a cracked float, so I thought that was the issue. I decided to replace floats and needles in both carbs as a preventative measure for the lower one.

The Mercury book is pretty specific, and I tried to follow it to the letter. Here is a scan of the Mercury manual for my engine.



I spoke with the company that makes the white float (Sierra), and they said that float drop being 3/32 from the main jet is not a big deal. So, I installed both carbs with the "float level" set at 5/16" exactly, and with "float drop" slightly off target. However, fuel squirted out of the vent jets on both carbs, not just the upper!

Both inlet needles are brand new, as are the floats. The needle seats are not replaceable on the Walbro WMA 3 series carburetors (they are permanently pressed into the carb body), or i would have replaced them as well. Instead of solving one squirt issue, I now have two! Both carbs are spotlessly clean, so I'm stumped.


Should I go rouge and toss the book criteria and continue to bend the metal tab which contacts the inlet needle spring until I get the needle to seat and hold pressure from the prime bulb regardless of float level or drop?

Thanks for educating me on carburetors. Real life experience like you folks have is far superior to a book which can't listen to input from a novice mechanic like me.

 

[Justinchap]

Re: Walbro WMA 3 carburetor: float drop question.

What became of this issue? I'm having the exact problem.

 

[oldman570]

Re: Walbro WMA 3 carburetor: float drop question.

With the carb off and the carb bowl removed, you have to measure between the float and the carb top body to get them set. The needle should be down and seated and the float should be near paralle with the top of the carb body where the bowl seals. By hooking the tank to the carb with a hose and primeing the carb while it is still off the motor will tell if the float is set correct or if it needs to be set lower and save the trouble of replaceing it on the motor and then haveing to take it back off if it is not right. Sometimes you have to go more than what the 5/16" that the book calls for, as the Serria floats are aftermarket and can be diffrant than factory Merc floats. JMO
Oldman570

 

[Star]

Re: Walbro WMA 3 carburetor: float drop question.

Justin it sounds like bad floats to me! Most of the time I spend the extra money to buy original Mercury parts for my motor. these quirky things can apear when using aftermarket parts.

 

[Justinchap]

Re: Walbro WMA 3 carburetor: float drop question.

Thanks guys. I think I got it figured out finally. I adjusted the float little by little and testing it with the fuel line and primer bulb until the needle would seal off in the seat. I agree with getting original equipment, usually better quality control. The merc floats were out of stock, so I took a chance with Sierra. Maybe I'll just wait next time to get the good ones.

 

[oldman570]

Re: Walbro WMA 3 carburetor: float drop question.

Gald to hear that you got the float set. Setting them on the bench with the tank and hose hooked to the carb sure save alot of time.JMO
Oldman570