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Float level confusion.

P

Peter Devil Ears

Regular Contributor
Hi, I have a 1979 175HP Black Max. When I pump the bulb before the first start of the day, fuel comes out of the carbs, all of them, as if the float levels are incorrect. I checked the service manual and it states the when I hold the carb bowl upside down, the float should hang 1/16th or 1.6mm from the lip of the bowl. I adjusted all of them, and the needles seem OK since I cannot blow through the carb inlets when I hold the bowls upside down. Still, when I pump on the bulb, fuel comes out of all carbs. Is it because hand pressure is alot more than pump pressure, forcing more fuel past the needles? I remember the last time I saw this, the boat still ran fine and did not leak fuel once running.
 
How hard are you squeezing the bulb? Fuel pressure from the fuel pump only runs like 3-6 psig range; not much. I squeeze easily until I get an abrupt change in the firmness of the bulb then quit.

Other thing is if your needle seats are not seating, float level doesn't really matter. Do they? Are the needle seats rubber. Are they perfectly conical or do they have a ring deformation? If the latter they won't seat correctly.

Fuel coming out as you say is only one of 3 things: Too much pressure, bad seat on the needle, or improper float level....oh and one more....float that doesn't float any longer.

Mark
 
Mark has a point: Pumping the bulb can generate 15 pounds pressure--I've measured it. Still, a well set up carb will not leak even then.

You have two choices: go easy on the pumping--just enough to fill the carbs--or adjust/ replace the needles and seats.

Jeff
 
i would fix it..good winter time project...rule number one ..if you know something is broke on an outboard then fix it....or wait til several ''unimportant'' things break and you got a pile of junk...just my opinion...
 
Thanks for all the assistance. I ordered new needles/seats. The new parts have not arrived yet, so I adjusted the float levels according to the manual. I took it easy on the hand pump and the carbs did not leak fuel. The boat runs great. I did get fuel leaking from the carbs when pumping too hard on the bulb, so I will replace the needles and seats when they arrive just in case. One of the needles definitely has a bit of a ring formed in the tip. The tips are rubber.
 
Feedback: I replaced the needles/seats eventually. I can now pump the bulb as much as I can, no leaking. Just don't try this with the motor trimmed up high, then it does leak! Makes sense.
 
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