New to small engines need help Yamaha 4 hp

[nightimefishn]

Hello,

A buddy of picked up a mid 80's 4 hp yamaha outboard short shaft for his dingy. Changed the impeller and thermostat with him this weekend and the engine runs great.
We had it started in a garbage pail at home worked well no issues.

When we get to the dock with the dingy couldnt get it started until we got sprayed some starter fluid in the carb. Ran fine the rest of the day no issues. Bring it home put it in the pail and same thing couldnt start without spraying.

These small outboards do not have primer bulbs I noticed. It seems like its starving for fuel but once its running its fine. Do people add a bulb of some sort between the tank and the carb? I am assuming its a mechanic diaphragm type fuel pump. Maybe that is bad?

I did notice one screw was missing from what i think is the pump picture attached.

Any help would be appreciated.

 

[99yam40]

Re: New to small engines need help Yamaha 4 hp

If this thing is using a remote fuel tank then yes it would need a primer bulb

 

[nightimefishn]

Re: New to small engines need help Yamaha 4 hp

Sorry I didnt mention it has a built in 1.5 gallon tank

 

[99yam40]

Re: New to small engines need help Yamaha 4 hp

Then check to make sure line from tank is clean and not restricted and check the pump for proper operation

 

[bag007]

Re: New to small engines need help Yamaha 4 hp

Yes there is a screw missing from the pump. This could be the problem... However, I would be more inclind to think its the carb.. no gas getting to the motor at start up... and when you uses the starting fluid.. this creats enough pressure from the motor running for the pump to actually force the gas through.... I would actually replace that pump .. or at least get a pump rebuild kit, replace the fuel line , clean out the gas tank and then rebuild the carb too....
I could be that the missing screw is the problem and the pump isnt keeping its vaccum at low pressure ie when you start but has enough "omph" when the motor runs... But I would still complete all the above...

 

[nightimefishn]

Re: New to small engines need help Yamaha 4 hp

Going to start with rebuilding carb. Cleaned tank already changed plugs and water pump.


Thanks!