50hp Yamaha 2 stroke outboard fuel problem?

[matty12354]

Hi this seems to be a common problem on here but i cant find my exact problem so.....

Engine starts and ticks over perfect when i select gear it does about 4hp on near full throttle when i go full it wants to die out, I think it is a fuel problem as the fuel filter before the engine when full it wont stay full once the engine is running and using the fuel the filter nearly emptys and only a small amount is coming from the tank to the filter enough to just potter along.

I have tried new connections new hoses, diffrent size hoses, diffrent primer bulbs, diffrent tank, checked pick up tube am i doing something wrong i have videos off the issue.

 

[jimmbo]

Hi this seems to be a common problem on here but i cant find my exact problem so.....

Engine starts and ticks over perfect when i select gear it does about 4hp on near full throttle when i go full it wants to die out, I think it is a fuel problem as the fuel filter before the engine when full it wont stay full once the engine is running and using the fuel the filter nearly emptys and only a small amount is coming from the tank to the filter enough to just potter along.

I have tried new connections new hoses, diffrent size hoses, diffrent primer bulbs, diffrent tank, checked pick up tube am i doing something wrong i have videos off the issue.

Is the Throttle Cable hooked up? And are the Linkages on the engine moving?

 

[matty12354]

yea everthing connected and moving

 

[racerone]

Start with a compression test.-----Post your numbers.----Then see if each lead has spark that will jump a gap of 3/8" ( 1 cm ) on all leads.

 

[FishMan001]

I would say it's more likely to be your fuel pump.

 

[jimmbo]

Fuel pump may be the issue, but many pumps have been replaced, when the problem was the pump couldn't pump what it couldn't get.

 

[FishMan001]

Fuel pump may be the issue, but many pumps have been replaced, when the problem was the pump couldn't pump what it couldn't get.

Agreed, but the OP stated :
"I have tried new connections new hoses, diffrent size hoses, diffrent primer bulbs, diffrent tank, checked pick up tube"
So I assume the path from petrol to pump is OK.

 

[jimmbo]

Has he replaced the hose from the fuel connector to the pump? I used to take those connecters off, and run the Fuel Hose directly to the pump, just to eliminate a potential air leak. What about the fuel pump to Crankcase connection? I don't how Yamaha does it, do they mount the Pump directly to the Crankcase, or use a Hose to connect the Crankcase to the Fuel pump? If there is a leak there, the pump won't work as well as it should

 

[matty12354]

Thanks for all replys i forgot to add i just purchased the engine after it was rebuilt and everything was checked it came off another boat that had no issuses another reason i think its fuel, i am going down today to check for leaks ect is there any way i can add videos here.

 

[99yam40]

Hi this seems to be a common problem on here but i cant find my exact problem so.....

Engine starts and ticks over perfect when i select gear it does about 4hp on near full throttle when i go full it wants to die out, I think it is a fuel problem as the fuel filter before the engine when full it wont stay full once the engine is running and using the fuel the filter nearly emptys and only a small amount is coming from the tank to the filter enough to just potter along.

I have tried new connections new hoses, diffrent size hoses, diffrent primer bulbs, diffrent tank, checked pick up tube am i doing something wrong i have videos off the issue.

a better explanation is needed on what you said in bold above.

Also, Just for testing A piece of clear tubing tied in after the pump will show if air is being sucked into the pump somewhere.( look for air bubbles)

I have cleaned the carbs on my BIL's 50 several times do to plugging of jets in #3 carb.
one time his complaint was the motor started and idled well but when he opened the throttle the motor just bogged down under the load.

 

[FishMan001]

Also, check the colour of your plugs. Are they all the same ? Are they all brownish, or are they black, white, different, oily, etc.

 

[matty12354]

Update disconnect fuel cinnection to the engine primer bulb went hard as soon as connect it goes softer, took the fuel line off the pump at carbs clamped it bulb still did not go hard so am quessing its the fuel pump, alo everything looked ok inside could it be the connection to the engine causeing it maybe?

 

[matty12354]

View attachment VID-20220702-WA0010.mp4

 

[matty12354]

as i had it clamped and pumped the ball the petrol seemed to come out the air intake at back off carbs when i took it off fuel was indide not sure if its cause it was at tilt or can the fuel somehow get threw the fuel filter if it is damaged just dont know how it would get there when i disconnected at the tee piece.

 

[flyingscott]

Have you tried pumping the primer ball to see if that makes a difference? Are you going to do the compression and spark chek?

 

[99yam40]

simple enough to take the pump off and see it has a problem.
I still have no idea what 4hp means on near full throttle

hp usually means Horsepower

 

[racerone]

Motor is making way too clattering noises.-----Stop running it and start inspection.----Compression test.----Check gear oil.-----Check for bad bearings.-----Sounds like scrap to me.----Sorry to be blunt here.

 

[99yam40]

too much fuel to air along with too little fuel to air will not allow a cylinder to fire and burn the fuel.
sounds like you have some plugged up jets and the motor is lean sneezing, but dumping fuel is what you need to chase right now

 

[matty12354]

simple enough to take the pump off and see it has a problem.
I still have no idea what 4hp means on near full throttle

hp usually means Horsepower

sorry i