Question about my Merc????

[colonel42]

I have a 40 hp merc which has been a great motor until last weekend. Starts great. Idels fine. 1/2 throatle fine. Wide open for about 200 yds and dies. Fires right back up, Ball is hard. Gas tank is full. Air valve is open. Before I tear into it anyone have any thoughts??

[gunflint]

Did you check the fuel line in the tank? That can work itself loose.

[colonel42]

Had that issue last year. That was the first thing I thought of. It was fine.

[SpecialK]

Not an expert but if it has a float bowl it may be a sticky float and needle valve. Half throttle the bowls fills fast enough but wide open it's using more gas than would be supplied.

[Rost]

Fuel pump diaphragm?

[marine_man]

That's kind of a tough call...

Right now I'm guessing (and I mean pretty wild right now) but maybe there's a chunk of something stuck in the high speed jet.

Normally if it's a fuel pump diaphram it would draw the primer bulb down or compeltely flatten it... so I don't think it's that...

I'd try and replicate the problem and when it's dying out try hitting the choke and see if the motor picks up. If it does it's a high speed fuel delivery problem which will narrow it down quite a bit.

It could be as simple as an adjustment to the high speed needle, but if you haven't adjusted it before it shouldn't need to be adjusted...

marine_man