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Force 50hp misfire when hot

nelly08

New member
Hi all. I bought a boat fitted with a force 50hp (an early model). The engine runs and starts without fault other than after a fullthrottle run it sometimes misfires. When this happens it wont clear up (usually on the return journey home). The engine does not currently have any over temp warning devices fitted as they were all melted! I have sealed the water pump as it lacked water flow but the head still gets very hot! I suspect thermostat from what I have read, and this could also cause the misfire if im correct? I also found the ht leads had melted from the heat on the block but I have now delt with that! I have video'd the engine running to show it does run. On compression test both cylinders came back at 110psi.



Any help would be appreciated. Thanks, Josh
 
Josh, Jerry is the Force guru here, I'm sure he will help when available. If I may though, your bucket is too small to be running an outboard in. Lack of sufficient water to the pump will kill the impeller in a mater of seconds. You will risk frying the powerhead. An overheated powerhead can cause misfire. A set of muffs or a 12 buck 32 gallon trash can would be much safer. You also need that over temp alarm working properly as it is the early warning to engine failure.
 
Like Dave said,the pump needs to be DEEP in the bucket or the muffs duct taped in place.
The water needs to be at least 2-4 inches over the cavitation plate.
These pumps won't suck the water up into the pump.
They need to be under water to get primed.
The 50 needs a special muff to cool right.
The big muffs might work, just not as good.
The pump looks like it's working and then running out of water.
It takes a LOT of water to keep these cool.
Your little bucket ain't enough.
If it's getting hot and misfiring? It's probably getting ready to seize.
The carb set right at 1 turn out and then adjusted from there?
The thermo take it out and test it.
It needs to be in there,as they operate best at a certain temp.Tach and stuff 001.jpgTach and stuff 002.jpgTach and stuff 001.jpgTach and stuff 002.jpg
 
How do I set the carb? Im an injection man and have never set carbs (other than the lawn mower! ). Thanks for the replies though guys. Will have a look at it this evening.
 
In the water.
Motor warm.
In gear.
Rpm's set at about 750-800
Top screw on the carb, turn it in till it just bottoms out.
Then 1 and 1/2 turns out.
Then turn the screw in 1/8th turn and let it run for 10 seconds.
Then again 1/8th turn out.Wait 10 seconds.
Do this until the motor kicks,bucks or stalls.
Then turn out 1/2 turn.
The 10 seconds is allowing the motor to burn the gas at the old settings.
 
Hey guys. Thanks for the responses. Took the thermostat out (stuck in place) and ran it up. Water flow is better than it ever has been and the head stayed completely cool! Set the fueling up and it seems to run more stable also! The timing is set to around 17 degree's at idle, is this okay? Thanks, Josh.
 
Usually the timing won't change unless you do something to it.
Put the thermo back in.A new one of course.
The motors are designed to run at a certain temp.
If not running at the right temp, it can carbon up,burn more gas and just not run as good.
 
Ordered new thermostat and over temp switch. Question I ask about timing is that its 26 years old and someone previously may have adjusted it. Are these engines okay to run with hydrofoils? Put my boat on a diet which has helped but the rear end sits low and takes awhile to get onto the plane. Any work better than others?
 
The slow plane? maybe the trim pin,might be in the wrong hole?
Tilting the motor too far up?
Looking at the video it looks like it's up a bit too far.
There are 5 holes it's in #3 try #2 maybe #1?
If it is? Then the fins might make it worse????Try adjusting the pin and THEN add the fins.
Almost any fins will work.
 
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