Yamaha Pro50LH

[DeweFole]

I have a 1987Yamaha Pro50LH that has set idle for about 8 years. It starts easily, then runs fast for about 15 seconds that goes back to an idle. It idles roughly and dies sometimes quickly and sometimes after a minute of so. I have had it on the water and it runs but seems to have less power than it should.
There seems to be good spark to the plugs on all three cylinders, but not much intake on the lower cylinder carb intake. I have removed the needle valves and they look clean.
Do I have a carborator probem? What are your suggestions?
Thanks for your help.

[99yam40]

check compression on all cylinders, you may have run lean and caused a problem.
Also check the fuel pump to make sure it is not dumping extra fuel into #3 through the crank case

[DeweFole]

yamaha pro50LH

Thanks for the recomendations for my 87 Pro50. I found that there were cracked fuel lines going from the fuel pump to the carbs. there was a fuel bowl gasket that was crimped and fuel line that was cracked. I got the gasket place in properly, Now my new challenge is to find replacment fuel line for the motor. I understand that USCG type A1 is reccomended but I can't find it. Any suggestions where?
A work in progress.

[rodbolt17]

type A1 line simply wont fit , its to large on the out side diameter.
quickest way would be to use a site like this and order the nessasary lines.
type A1 is only required for underdeck usage.

[DeweFole]

Type A1 fuel line

Thanks, It now makes sense why I am having trouble finding the right size of fuel line. What are the reccommendation for line type? Can I use clear polyurathane tubing, or clear lawn mower fuel tubing? If so then I can find tubing that will have the right OD.

[99yam40]

buy the fuel lines that are made for your motor by Yamaha. They are formed and expensive , but made for your motor. look them up on this web site and order them. Just click on the Purchase Yamaha Parts at the top of the screen

[DeweFole]

1987 Yamaha Pro 50

I replaced the fuel lines with the Yamaha parts, restarted the engines. It runs better but is still rough. The ****erflys on the carbs do not open but a small amount. They are connected to a rod that runs to the oil pump. The pump arm seems frozen. It does not move. Is this normal or has the pump frozen and needs replaced. the carb ****erflys open and close easily when not connected to the oil pump. So any advice would be appreciated.