Power loss

[2botes4fun]

I have an 87 70ETLH 70 hp Yamaha pushing a 20' Skeeter pontoon. Of late, this outboard has a power fall off after 10-15 minuntes of run time only to shut down entirely. I have checked the fuel lines, replaced inline filter cartridge & vent port to the tank, changed the plugs.....it has plenty oil in resevoir. The impeller is not suspect here. It does restart after sitting for 5 minutes or so, but the condition doesn't change & we limp back to the lift. I'm suspecting either fuel or oil pump going bad .

Thoughts here Gents?

[boscoe99]

Between fuel and the oil pump my guess would lean towards the fuel.

Oil pump failures are extremely rare. Oil pump failures don't fix themselves such that you can run for 10 -15 minutes the next time that you use the motor. Or, such that you can limp back to port. If an oil pump fails the engine should be ruined. Eventually the motor should seize. If the oil supply gets low then you should be hearing the warning horn and seeing the low oil condition on your Yamaha tachometer.

Do your horn and tachometer work?

Fuel supply issues are quite common. Particularly on a 28 year old motor.

Try using the primer ball when the motors starts to lose power. Before the motor dies. Does the power come back or remain lost? Hold the primer ball vertically with the outlet on top so that can be most effective.

[2botes4fun]

Tks boscoe99.

Im gonna replace the fuel line & primer bulb as it is showing age, tank vent too.