Flooding Carb

[SimonC]

My 55 Yamaha twin cylinder has just started to drop onto the top cylinder only at idle and low revs. As the revs increase and the boat gets onto the plane it normally picks up so that both cylinders are firing normally.<br /><br />I noticed that fuel appears to be running out of the front of the bottom carb which suggests to me that something is stuck.<br /><br />I've checked all electrical elements on the motor and am convinced that the problem is fuel related.<br /><br />Does anyone have any ideas where I should start to solve this?

 

[WillyBWright]

Re: Flooding Carb

I suppose I'd have a go at that bottom carb.

 

[SimonC]

Re: Flooding Carb

I'd guessed that much, what in particular should I be looking for?

 

[Ray Neudecker]

Re: Flooding Carb

Expect to find a stuck needle valve or a float out of adjustment.

 

[SimonC]

Re: Flooding Carb

At last found the time this weekend to have a look at the carbs. Stripped both down and found no problems at all. <br /><br />However, I did decide to have a look at the reed valves and to my horror discovered 2 bolts complete with washers stuck in the lower set. Further investigation determined that these had come from the backing plate on the airbox.<br /><br />I can't believe my luck, if this engine hadn't had the reeds I'd have now been shopping for a new motor.<br /><br />Reassembled everything, adding a bit of Loctite to every bolt and she fired up just fine.<br /><br />I can only assume that the flooding problem was caused as the 2 bolts worked their way through the card throat.