I have a 1987 50 hp Force. Engine starts and idles normally. When increasing speed (throttling up) the engine begins to run, then feels like it is going to stall, then revs back up, then again feels like it is going to stall. This continues until the engine actually does stall. It will eventually start back up, but this process continues.
Had the same problem with my Force 50hp. Trial and error testing, I found two problems. #1, the fuel line in the 6gal fuel tank, between the brass fitting in the top of the tank, and the inline filter inside the tank( fuel pick up line) was fallinf apart and plugging the fuel supply line. #2, the priming bulb has at least one check valve in it that was not working properly and the bulb would suck dry when underway, but not at idle. Replaced the interior line and fuel filter, replaced the priming bulb and never looked back. Repair cost about 10 bucks.
2 other possibilities I found with my 507F7C 50 HP Force: 1) torn fuel pump diaphragm impeding gas flow: screw that should have been holding valve in place had become dislodged, and tore the hole in the diaphragm, the screw itself also slowing fuel flow. Under increasing flow pressure, the diaphragm is pulled into the valve hole in which the fuel should be flowing uninterruptedly. Check diaphragm. It must be in good form and consistency to build pressure and deliver the fuel.
Last edited by inquizito; September 22nd, 2009 at 09:52 PM.
Reason: improper wording