2005 Lund 1850 Fisherman – Sputters at full speed

I have a 2005 Lund Fisherman with a 2005 Mercury 150 hp 2-Stroke Optimax. At 3/4 throttle no problem, but at full throttle it starts to sputter and wants to cut out. The primer bulb gets sucked dry at full throttle, so it’s not getting enough fuel. So I don’t think the motor is the problem. When it starts to sputter I cut back from full throttle to 3/4’s and the bulb fills with gas again and gets hard.

I learned today that some boats have a Water Separating Fuel Filter. Could an old filter be the problem? Bad printer bulb? Blockage in the fuel line?

Thank you!

Yep check for filters first.

Thx Dutchboy. I bought the boat new. Where would I find the Lund Water Separating Fuel Filter? Do I take the panel off where the fuel hose from the motor connects to the boat? Or is it close to the fuel cap where I put gas in the boat? Thank you!!!

I would look around the rear splashwell. Follow the hoses back from the motor. But, if the motor is new you shouldn’t have filter problems unless your first load of gas was bad.

Make sure there are no kinks in the line.

Might want to touch base with the dealer and let him know whats going on.

I can’t say I’ve heard of one built in a boat, but it doesn’t surprise me. My o6 Verado has a fuel filter and a water separator filter on the motor, water separator is on the left side if you follow the fuel line. Also check your fuel tank vent on the outside of the boat doesn’t have a leaf, debris, or wasp nest in it.

What do you mean sucked dry? Primer bulb will get hard when initially pumped to create the pressure, but once engine is started and running it just becomes a free flowing line with no “hardness”. Is it actually getting concaved in while running?

Just want to make sure we’re chasing the right problem here

Might be the fuel filter in the fuel pick-up PVC tube at the bottom of the gas tank gets clogged when the motor is sucking fuel fast (full throttle). When you back off on the throttle it sucks less and the debris around the fuel pick-up disburses.
I’ll bet you’ve got debri in your tank and it sporadically clogs that little filter…which is nothing but a fine wire mesh.
It happened to me. And when I filled the gas tank up the problem went away…until I got back down to about 1/4 tank left, then the problem started again.