Power Loss at WOT - 1982 50hp (4 cyl.)

[imported_Voyager]

My 1982 50hp mercury "M50" (4 cyl.) is running at about 5000rpm @ WOT when pulling a tube or when the boat is loaded. In these conditions, the motor will starve for fuel. (Squeezing the bulb restores power.) Running at lower throttle settings isn't a problem. Prop is a 10" x 13 pitch. The boat is a '57 Crestliner 18' (aluminum), a light boat that planes easily, with a hull form that builds drag quickly at higher speeds.

The carbs were freshly rebuilt, the fuel line/bulb/fittings are new and good quality (Moeller) and the tank is vented.

Since I'm likely to be loaded and/or pulling kids on a tube, I'm going to drop to a lower prop pitch, perhaps a 4-blade 10 or 11 pitch. Is it possible that the fuel delivery issue will be solved by turning faster at WOT? It's hard to believe that the pumps are that marginal, but I don't know what else to try...

 

[imported_Voyager]

Re: Power Loss at WOT - 1982 50hp (4 cyl.)

Tested this weekend with the boat very lightly loaded; WOT gave me 5500rpm and at that speed, the problem didn't show up.