Lost spark to a cylinder. 90HP Force 1991

[criddy72]

Hi,
Thanks in advance for any help. I recently bought a pontoon with a 90HP Force 1991 model. It hadnt been used in three years. It doesnt have oil blending. I drained the fuel, fogged it a little for its first start, replaced the starter, impellor and lower fluids.
Well it ran great for about a month then lost power. I traced it down to which cylinder and presumed i needed to replace the plug, did all three and no difference, then presumed a new coil pack, replaced it and still the same. Compression is good just no spark.
It used to run to 4100RPM WOT loaded. When it happened WOT was 2400RPM. Idle is rough etc.

Any help would be appreciated.

 

[Justinde]

Re: Lost spark to a cylinder. 90HP Force 1991

Need spark to run check wiring, kill switch ( if you have one) etc, but you of course, need spark, or it aint going, unless its a diesel!

 

[mauiboy]

Re: Lost spark to a cylinder. 90HP Force 1991

Try checking the spark I have a 88 85 hp and it turned out that one of my power packs were bad look at my post on no power and good luck

 

[criddy72]

Re: Lost spark to a cylinder. 90HP Force 1991

Thanks for the reply but as i mentioned above i replaced the plugs and the coil pack that wasnt putting out any spark. Even with the new coil pack on cyc #3 i still have no spark. If the kill switch was bad then none of the cylinders would be firing.
My question was, what is upstream from the coil pack that could be bad and not giving the coil pack a signal to fire?
Thanks

 

[steveclv]

Re: Lost spark to a cylinder. 90HP Force 1991

Is the coil pack getting voltage - if you can, get a pin and attach a 12v led to it and push it into the lead wire of the coil to test that it's getting a voltage make/break several times a second (unless it has a connector that you can easily get at). Regular bulbs don't react fast enough to see the voltage spikes. If it is flashing then it's either another bad coil or a bad ground. If not then you need to check the wiring back to the stator under the flywheel where the pulses originate. May be lucky and find a simple broken wire - fingers crossed for you!

 

[jason32038]

Re: Lost spark to a cylinder. 90HP Force 1991

Before my 86 85 blew I had the same problem as you. My issue was a wire that came out of a connector from the cd module. Fixed it and she screamed for a few minutes until I came back to shore at idle and took her out again. I melted a piston in that short amount of time...i think.

 

[criddy72]

Re: Lost spark to a cylinder. 90HP Force 1991

Well it would appear apon inspection this morning that one of the magnets under the flywheel has come loose. It is being pushed around by the other magnets and has worn a nice groove in the stator. I am guessing this is a problem!!! Lol. I wouldnt have thought a magnet would come loose!