1981 70HP - no spark on number 1 Cyl

[Toddo1]

Checking with a spark tester, theres no spark on number one cylinder. 2 and 3 have good spark. I suspected the number 1 coil. However, when I switched the 1 and 2 coil wires at the power pack plug, the number 1 coil fired and 2 didn't.

So, before I go and purchase a power pack, should I be looking at the stator also? Could a failing stator cause one cyl to not fire? I haven't done any testing on the power pack. The stator doesn't appear to be leaking, although I haven't had the flywheel off yet for a good look.

I scoured numerous other posts, but didn't see any that referenced only one cyl not firing.

BTW, thank god for this site and you guys )

 

[Joe Reeves]

Re: 1981 70HP - no spark on number 1 Cyl

Unlikely the stator is at fault. Find the sensor wires leading from the timer base to the powerpack. There will be three of them that trigger a SCR in the powerpack to fire the coils.

You can switch those wires around as you did the primary coil wires. Connect #2 or #3 sensor to the powerpack terminal that fires #1 coil. If the coil now fires, the pack is okay. If no change, replace the pack.

There may be a problem in the rubber connecting plugs.... a pin or socket pushed back and not making contact, a frayed or broken wire at one of those rubber connectors. Let us know what you find.

 

[Toddo1]

Re: 1981 70HP - no spark on number 1 Cyl

Thanks Joe.

I'll perform those tests and post the results.

Side note...those little aluminum pins in those plugs...are they available? I did see a frayed coil wire connection on one coil and would like to repair it. Those pins, being aluminum, are also pretty fragile and pushing them in and out of the rubber connectors isn't conducive to keeping them in good shape.

Thanks.

 

[Toddo1]

Re: 1981 70HP - no spark on number 1 Cyl

So, the Power Pack tests ok. I even got hold of a known good one and still the same no spark on number one cyl.

Correct me if I'm wrong....if the charge coil (stator) was bad, it wouldn't fire on any cylinder, but if the sensor coil (timer base) was bad it could possibly not fire on one cyl but fire on others?

After reading the service manual, it seems the stator provides current for all cyls to fire, and the timer base provides the signal for when each cyl fires.

 

[Joe Reeves]

Re: 1981 70HP - no spark on number 1 Cyl

You are correct in your thoughts pertaining to the stator and timer base. Your tests would lead me to the timer base and/or the connecting plugs sockets/pins.

The sockets and pins can be purchased at your local dealership.

Switch the timer base wires temporarily at the connector so that #2 will be firing #1. That should tell the tale.

Also, with a ohm meter, check the timer base sensor wires. They should all read the same. Hopefully your problem is simply a broken wire of a pushed back pin/socket.

 

[Toddo1]

Re: 1981 70HP - no spark on number 1 Cyl

Well, I finally replaced the Timer Base and I now have spark on all cylinders.

Thanks Joe, much appreciated.