1987 40 hp idling problem

[JRP026]

I have a 1987 40hp yamaha that has a idling issue. i have takin apart all three crabs and done a very good cleaning on them. When i run the motor off the ears the motor run just like a champ but as soon as it hits the water if idles just fine. i start to run the motor at a slow speed all is good then i put the boat up on plane and the motor runs but 15 mins in the run the motor just dies on me for no reason. Then you go to re-start the motor it has a hard time idling low. you have to have the idle lever mid way up to have that low idle. Then final it will idle enough to get the motor back into gear and run for another 15 mins and it starts to die out until i hit the choke and it takes off. I ran sea foam thru the motor with 93 gas and the same thing countines to happen, but as soon as i get home and hook the ears to it no problems.

[mitch]

Check the breather on your fuel tank........................i guess you have changed filters also check fuel pump .


Does squeeze bowl pump hard ? when this happens

[JRP026]

i have added a new in-line filter and and the the squeeze bowl is really easy to pump.

[JRP026]

the fuel tank is portable tank and i have tried to open it up.

[mitch]

does it have a air bleeder on the top ? it should go hard once the carbs are full

[JRP026]

yes it does and i have ran it open and closed. it does go hard when pumpimg the ball.

[mitch]

have you checked your fuel pump . the bleed should be screwed out when operating so air can equalize for the amount of fuel used

[JRP026]

thanks for that advice i will take the fuel pump off and see what happens then.