I have a Force 125hp outboard engine that seems to have a fuel problem. The engine runs fine at 20 mph. When I give it full throttle, the engine runs full for about 10seconds and then sputters, misses and backs down on RPM. I take it back to 20 mph and it runs smooth. I kick it back up and it runs full for 10 to 15 seconds and then sputters,misses and backs down again and smooths out at 20 mph. It's just like it's running low on fuel. I've changed the fuel pump diaphragm several times,all the cd modules, coils, stator, trigger, and rebuilt the carbs twice (floats are good). I've drained out old fuel and put in all new fuel mix.Compression is 140 psi in all cylinders. My next step is to hook up a 6 gallon outboard fuel tank with mix and see if there's something plugging the pickup in the tank. Any other ideas? Thansk. TW
Make (of engine): force
Model (of engine): 1254x8c
Rebuilt carbs twice. New fuel pump diaphragm 3 times. New cd ignition modules. New fuel mix. Compression is 140 psi. New trigger. New ignition coils. New plugs.New stator.
Try pumping the primer bulb and see if it picks up
New fuel lines and primer bulb installed. Does not make a difference to pump bulb when sputtering/missing. That's why I'm ready to hook an external outboard fuel tank to the engine for a run ( kids put something in tank?).The problem was noticed when I had the original tac and speedo gages go bad(1989 bayliner cobra). New gauges installed now for a 4 cyl outboard force system Any other suggestions?
Yes try that first, then try removing the tach wire, a bad tach can cause a miss alsoIf those are good check compression and spark after that
Over a 15 years of working on all the brands of outboards.
Compression checked yesterday at 140psi on each cylinder. Would a tac problem only cause a miss at high rpm? It runs great to 20 mph. Backs down to 20 mph and smooths out. Thanks.
The most likely cause of your issue is a fuel restriction in the boat side fuel system. Try running on another fuel source. Also check for a miss wjhen running the engine using a timing light when nthe engine starts to act up. What you are looking for is the flash of the timing light you want the flash to be steady. Post back with questions. The tachometer will not cause an ignition miss fire. The tach get it's signal from the charging stystem and has nothing to do with a miss fire.Tan Partin41105.9991434028
35 yrs. experience. I/O, Outboard & Inboard, Complete engine repairs.Certified Technician
You need to double check the carbs again and check for spark with a timing light on the cylinders
Now he is repeating what I had already said.