carb. question- 48 spl

[71mfg]

I have, I think a 91' 48 spl. I've been trying to take it out. I can start it in my driveway, runs perfect, take it to the ramp in the water, runs like crap. Won't idle correctly, if I can get it into gear, floored, maybe 5 mph. Bring it home, hook up the water runs perfect. Whats the prob.? This is what I've done, cleaned up the plugs, new fuel line, made sure fuel pump screen was clean , flushed tank. I'm suspecting a carb issue. before writing this I took the plate off in front of the carbs., started the motor and shot carb. cleaner in each venturi, the bottom one would actually increase rpms and the top carb would kill the engine everytime. any input would be appreciated.
Charlie

 

[71mfg]

Re: carb. question- 48 spl

bump

 

[tashasdaddy]

Re: carb. question- 48 spl

WILL RUN ON MUFFS IN DRIVEWAY

Motor runs perfect at home. Get to the water, it won’t start, won’t idle, can’t stay running to get into gear.

The idle setting has to be fined tuned when the lower part of the engine is submerged in the water. This is the operating condition of the motor. The exhaust exits under water, this causes, backpressure on the exhaust.

When you set the idle while running on muffs, there is not any backpressure, so you add backpressure, and the motor will not run. The idle has to be set higher on muffs, so the motor can run when in the water.

Final adjustments to the idle speed HAS to be done IN THE WATER, WITH THE MOTOR IN GEAR.

There can be other contributing factors, such as dirty, varnished carbs, low compression, poor spark, or link & sinc.

 

[71mfg]

Re: carb. question- 48 spl

I've never touched the idle screws, what about the different reactions to the carbs. I did find out that my motor is a 89' both carbs have a screw on the top stb side, are these actually idle screws or jets?
Charlie

 

[71mfg]

Re: carb. question- 48 spl

Success! Took the carbs apart top carb. was clean as a whistle, bottom carb had some trash in it but no varnish. The top carb was dry, I don't think it was getting fuel. so I recleaned the fuel lines back to the fuel pump and believe there was a blockage at the manifold where the fuel line splits into three. Anyhow took her down the river and it ran great.
Charlie

 

[tashasdaddy]

Re: carb. question- 48 spl

congrats!!!