ignition coil

[fisheymikey]

force 125 1988
I checked the coils resistance and on cylinder 2 coil reads no resistance but I do have firing due to spark plug carbonisation.on all other coils I get 900-1000
can that be a reason why I don't achieve my 4900 rpms
when the boat did not run for a while and its very cold the boat runs a lot faster then as the summer continues it gets slower and slower

thanks

 

[pnwboat]

Double check the spark plug connection on the spark plug wire. Take the spark plug boot off and look at the metal connector that snaps onto the spark plug. Be careful because some of the boots are pretty old and brittle so you may end up damaging the boot. There are several designs. One of the designs looks kind of like a spring. The end of the spring is bent at a 90 degree angle and punctures the jacket of the spark plug to make the connection to the wire inside. Corrosion where the end touches the wire inside will prevent you from getting a good reading with an OHM meter, yet it's good enough to pass the high voltage to the spark plug.

 

[fisheymikey]

I installed new boots. checked directly the wire to ground... 0 ohms that I could be certain.
question is. can a spark plug fire even if there is no resistance or even better it would fire under idle but not under load?

thanks

 

[pnwboat]

I would replace the coil. You should read continuity on the coil windings. No resistance would indicate an open winding or bad internal connection in the coil itself.

 

[glenn property of pam]

buy a spark tester they cost about 5-10 bucks max at any auto parts store. Open the points to 3/8" and the spark should be bright and snappy.

 

[MickLovin]

Ignition coil primary is normally a very low ohms reading so I am unsure if your other 3 are ok, if #2 read low ohms like 0.8+ that would sound right to me. Do you have a manual and if so it may state the measurements in there. On the secondary side of your coil the High voltage side you will read higher ohms like your measurements, so if it is #2 reading 0 ohms on the secondary, I would replace it.

 

[jerryjerry05]

Like Glenn suggested get a spark tester.
Do a compression test.
What prop is on the motor?
It's possible the coils breaking down?
Or the wire connections have a bad connection.
Replace all wire connectors on all the leads.
If it was missing? You'd be able to tell while it's running.