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Tony can you help

G

greg

Member
" 1995 mariner 25 hp.
Goes t

" 1995 mariner 25 hp.
Goes through phases where it will not start at all with the starter but it will start with the pull cord. Then through phases where it will not start with the cord or the starter. The plugs are new. When going through these phases I've checked the plugs and they are wet with gas (not flooded). When it does crank it runs fine no misses or hesitation.

It appears to me, something is causing it not to get fire to the plugs some of the time. What could cause this? I guess this motor has electronic ignition. But could something equivalent to the coil be going out?

Also, the starter is dragging but most of the time it spins it plenty fast enough to start the motor. Could the starter going out cause some short in the firing system?

Any help would be appreciated.

I Have more details. I took the plugs out and left them hooked up the the wires. When the engine is turning the top plug sparks about 3 times then quits and the bottom plug appears to spark properly.

Keep in mind that at times over the day when it did crank it would run fine but when it was turned off it was very difficult to get back cranked. "
 
"Greg,

I would check the st

"Greg,

I would check the stop switch first. Disconnect it and see if the engine starts easier. You can disconnect it at the switchbox. There should be a plug type connector there. The color of the wire should be black/yellow stripe.

If that does not help, I would check the trigger, switchbox, and ignition coils next. The switchbox is probably the most likely of these three to be faulty. I believe it is situated on the exhaust cover plate, and is very susceptible to any increase in engine temperature.

The starter is not in the ignition circuit, but if the starter is draining the battery, it could cause the charging circuit to deliver a very high rate of charge which could cause the stator to heat up too much. The windings for ignition and charging are separate, but they are both in the stator assembly. If one is getting too hot it will cause the other to heat up also.


"
 
thanks for the info Tony. I

thanks for the info Tony. I have more details.

I changed the coils around. When i did this the bad plug changed from the top to the bottom.

Does this mean it's most likely the coil?

Is there a way to test the switch box?
 
" Greg,

I think the coil is

" Greg,

I think the coil is most likely the problem based on what you have observed.

To test the switchbox output accurately you need a peak reading voltmeter. The same is true for the trigger and stator.

You could test the spark by holding the plug wire near a source of ground. You should be able to get the spark to jump a gap of at least 7/16 inch. If you can't get this to happen, the spark is weak.

You can test the coil for resistance with an ordinary multimeter, but this test may not always be helpful. Touch the test leads to the terminal that the plug wire is attatched to and to the ground wire. Then touch the leads to the primary terminal (where the wire from the switchbox is attatched) and the ground wire.

Tell us what readings you get.

Tony "
 
I went ahead and got two new

I went ahead and got two new coils ($30 each)figured if one went out the other may not be long. I will try this tonight and let you know.

I really appreciate the input.
 
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