120 Force misfires during cold start up

[gzisk]

During cold start, engine turns over but then misfires after a few revolutions and knocks out. Changed plugs and wires without success. Appears to be electrical, because once the engine heats up it runs pretty well. Engine was rebuilt about 50 hours ago, power head, crank, carbs, etc. <br />What do I try next? Coil packs? How do I test? Can I change one at a time or all? Other suggestions?

 

[Laddies]

Re: 120 Force misfires during cold start up

Take sounds like a lean idle mixture

 

[roscoe]

Re: 120 Force misfires during cold start up

Thats what I would check too.<br />Increase the fuel to air mixture by turning the mixture screw a 1/4 turn counterclockwise, on each carb.<br /><br />Are you using the choke?<br />Are you advancing the throttle when you try to start it?<br /><br />Don't know if you are new to boats or not, but lots of people are not familiar with the choke and throttle advance when they get into boating.<br />If you need more info, just ask.<br /><br />If you post the year and model of your motor, I can provide a diagram of your carb.

 

[imported_bjs]

Re: 120 Force misfires during cold start up

i didnt know there was a special way to start a motor.squzee the primer bulb 1 st. i push the key in while i'm turning over the motor.then i let motor idle for about 10 sec.and away we go.

 

[roscoe]

Re: 120 Force misfires during cold start up

Lots of people coming from smaller or different brands of motors, have no idea that the choke is activated by pushing in on the key, or that you can advance the throttle without engaging the motor into gear.<br /><br />Many people under 35, have never operated an engine (car/boat) that wasn't EFI, they don't know what a choke is.

 

[gzisk]

Re: 120 Force misfires during cold start up

Thanks for the suggestions. I purchased the boat and Force 120 hp engine in 94'. I am familiar with the choke and starting process. It's also easy to flood the carbs on this engine and have to wait 5 or 10 minutes. I'll try the carb adjustment next weekend, it can't hurt. <br />I seem to get good firing on maybe three cylinders, and then the fourth misfires and stalls the engine. This occurs three or four times until the engine finally turns over. But until it gets hot, I continue to hear the misfire but the engine continues to run.

 

[gzisk]

Re: 120 Force misfires during cold start up

The carb adjustment seemed to work. The engine is running smoother. <br />A nasty backfire before the engine kicked over on the second day cold start. Don't know what that was all about, but the engine started and ran smoother.<br />Thanks for the help!

 

[roscoe]

Re: 120 Force misfires during cold start up

cool