1993 Yamaha 6 hp

[johnson89]

Not my motor but a friend, motor starts on 1 pull and when you put it in gear and start to give it gas it bogs down. Getting way too much fuel, have it set up so I can see in the carburator, if you disconnect the fuel line and just before running out of fuel it goes full speed. The carb. Has been cleaned and I checked to make sure the float valve works, and it seats perfect . That center brass jet sprays a lot of fuel when you try to go pass idle speed. The motor has very little time on it, has 98 lb compression both cyl. New plugs. Not sure what else to check, never had a problem with 2 much fuel . I've tried raising and lowering the float and makes no difference, still sprays lot of fuel. Only one set screw on the carb. And it doesn't help either way

 

[johnson89]

Installed a carburator kit and made no difference, still sprays to much fuel, no leaks anywhere, rebuilt the fuel pump also and it was in good shape before rebuilding. The motor starts on 1 pull and idles good.... What am I missing :facepalm:, I've rebuilt my 90 Johnson from the ground up so I know a little about motors .

 

[QBhoy]

Apart from the obvious vent being closed on the fuel tank and carb defo clean as a whistle...can’t think what it could be. But.....I just hope your compression gauge is reading a little low, because you are really under the number considered as acceptable at anything less than 100 odd psi. Just a thought. Proabably your gauge though. Not much phases these wonderful engines apart from not having oil mixed in the fuel. I’ve had 2 8hp yam for decades now. Can’t beat them.

 

[johnson89]

Gas pouring out of the center brass jet when you accelerate past idle, been working on this for 4 days and getting nowhere . Will only accelerate when it starts running out of fuel ( unplug fuel line). I can keep it running strong by spraying gas straight into the carburator as long as the float bowl is empty.

 

[johnson89]

Okay tried something else, I blocked off the low speed jet and of course it will not start until I spray gas in the carburator but once in gear above very fast idle it will run strong and doesn't flood out. So either the low speed or the high speed jet is putting out to much fuel . I'm still at a lost.

 

[raczekp1]

what about flat, needle and needle seet?
fit there is any signs of wear?
did you install nozlle jet while carb cleaning?
did any one drill out main jet to uppgrade to 8 hp?
( besides this unit can be upgrade to 8 hp by unbloking exhoust)

 

[johnson89]

FIXED..... the last person who worked on the carburator didn't replace the black rubber plug over the low speed jet, yes a very simple carburator but when someone else tinkers and you don't know what they have done, makes a simple job a pain . Motor runs like a champ at all speeds . Thanks for the responses .