Why does my Force 50 HP misfire when trying to start

Force 50 user

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Joined
Apr 25, 2015
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2
I am trying to start my Force 50 HP 2 cycle and it misfires badly after I replaced one of the Ignition coils that had no reading on the secondary circuit.
I have been through everything that could be wrong. I have sparks ,I have fuel. The new replacement coil measures like 4000Ohms on the secondary only
instead of the 14500 Ohms it says in the Repair manual specs and the other coil measures.Could this be the culprit or what else can be wrong.
Please help me with any idea what I could have missed.
I would greatly appreciate your Help.
 

Jiggz

Captain
Joined
Oct 23, 2009
Messages
3,817
Is the misfiring only during start up and runs fine thereafter? If it misfires throughout do the following:

First you need to identify which cylinder is misfiring or not firing. You can do this by doing the "plug wire pull" to see if there is any change in the engine tune or if the engine dies. From there, switch the coils (always mark which one is which, it is very easy to lose track which one belongs to what cylinder) and see if the problem follows. If problem follows then you know the coil is bad. You might want to do this with the old coil you removed. And if you confirm the same coil is bad then you probably had a bad new coil.

If the problem does not follow, then you know both coils are good. Now it is time to escalate the switching of parts. Unfortunately, with only two cylinders there is only one CD module hence you cannot switch it around unless you have a spare one that is known to be working. However, even with one CDM, each CDM has two ckts in it with respective inputs and outputs. A wiring diagram will be very helpful. You can switch output wires from #1 (orange or blue/orange) to those of #2 (red or blue/red) at the same time you also need to switch the input wire from the trigger (white grn or white and white red or red) to the other input wires (white orange or green and white yellow or orange). Again check to see if the problem follows.

If it follows then one of the CDM ckts is bad and the entire CDM needs to be replaced. If it did not follow, then problem is most likely with the trigger. You need to do cold resistance check with the trigger first to see if there is any discrepancy based from the service manual. If there is then you might want to investigate further. If there's none, then it is time to check from the mechanical side i.e. compression, reed and carburetion. If you have a compression gauge you might want to do this initially to get it out of the way. Or if you are more mechanical incline rather than electrically, then start with the mechanical first.

I'm not sure what year is your 50HP but the above diagnosis is based on the 1988 "D" and later model.
 
Last edited:

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,923
Try adjusting the carb.
Turn(gently) the air screw in till it just bottoms.How many turns in?
Turn out 1 and 1/4 turns and then adjust from there.
 

Force 50 user

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Joined
Apr 25, 2015
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2
Thank You for your great detailed advice. I do appreciate it very much.
I have switched the Sparkplug wires and it started up ferociously but died after 1-2 seconds. I have tried it many times and it does the same thing every time.
I will check the carburetor again if the float and valve is set correctly and clean the carb.
Is there anything else you could suggest.
 

Jiggz

Captain
Joined
Oct 23, 2009
Messages
3,817
Before delving any further, make sure you have installed the clear fuel filter mod. I've already explained this in many threads and it is indispensable for fuel related troubleshooting. It doesn't have to be an expensive one since it's more for troubleshooting rather than fuel filtering. Wally World has the G2 Fram for less than $5 and it even comes with hose clamps. Try that first and post back what the status of the clear fuel filter when running the engine.
 
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