K&B 3.5cc outboard engine running problem

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K&B 3.5cc outboard engine running problem

Postby 777ER » Wed May 20, 2009 12:56 pm

Hi,
I have a tunnel hull with the K&B 3.5cc outboard engine (model # 8907) with a black carb (came with it when it was new.

I never had much luck getting it to stay running.

Everytime I put the boat in the water and it'd run great and fine for at least a few mins or so then it'd sputter and stop (about 3-5 seconds of sputtering) and most of the time it happened in the middle of the lake.

Everytime I retrived it and checked the fuel level, it's always between 1/2 and 3/4ths of a tank.

I even ran it in a water tank without any problems from full tank to empty under load, under various needle settings.

Even switched from CP 30% to 75%, tried small straw tubes in the water inlet thinking it may be overcooling the enigne...nothing helps.

Does anyone know what could be wrong with it?
777ER
 
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Postby lh7018 » Thu May 21, 2009 8:00 pm

There are a number of things that come to mind but start with something simple: the fuel tank set up. Where is the fuel pick up located in the tank? The suction tube should be in the left rear of the tank at the bottom (referenced as if you were sitting in the boat). If you set the tank up like one would for an airplane, using the short hose and clunk, that puts the pick up at the front of the tank (again as if sitting in the boat) and this can induce air into the system as the fuel sloshes around with the forward and up and down motion of the boat as it's in the water. It doesn't take much of a bubble to kill the engine. The fact that the motor runs under load in your water tank at various needle settings makes the tank set up my first thought. Let us know what you find, and if the tank is set up properly we'll look into other things. Hope this helps.
lh7018
 
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Postby badger » Mon Nov 16, 2009 10:15 pm

Had very similair problems you are having for years. Tried everything. Only once in a while mine would run a full tank in the pond. I put a perry carb. on it, tunnel hull has never looked back since.
badger
 
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Postby USMC » Wed Nov 25, 2009 11:53 pm

is your tank backwards?
which way is the clunk setup, to the front or back toward the engine?

try changing so the clunk is toward the rear.

good luck.
USMC & Viking...! & Little jack...! :)
USMC
 
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