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88 Mercury 99 no spark

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willis1985

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"Hi, I just bought a 88 mercur

"Hi, I just bought a 88 mercury 9.9 elec/start off a friend whos grandfather bought it new in 88. It has sat for over 17 years and only has between 5-10hrs on it. I bought with the assumption that it would need tinkering and repair to get it out of hibernation. I took it home, opened her up, and found years of rodent nest and some chewed coatings off wires. I tore everything down, cleaned everything, tested and repaired chewed wires, put a little oil in the cyliders, and than rolled it over to test for spark. I have none at all. So, I got the specs online for the ohm readings for te stator, coils, and trigger. The stator tested 3250ohms on the low side and 136 on the high side (from the specs i got, 225 is min for high side) The trigger tested 745 and the minimun is 750. Both coils tested good between range. Are these readings bad enough for the stator and trigger to say that they are definitly bad? Could there be something else simple wrong? Could this be a bad switch box? How could these components go bad with such little use and no corrosion? Any help is appreciated. I just dont want to go buy a $150 stator than a $50 trigger than a $180 switch box to find they dont solve the problem, if someone may know a common problem or has a simple solution.
Thanks"
 
"William, to start with, very

"William, to start with, very nice motor and worth getting going again.

Your resistance numbers don't sound bad enough to give you "no spark".

Disconnect the black/yellow wire that comes into the bullet connector at the bottom left of the switchbox.

That black yellow splits into two connectors under the front of the powerhead and feeds the two kill switches on this motor (the toggle switch on the side and the kill switch at the tip of the tiller).

If beasts have been setting up house, one of your kill switch wires may be chewed where you can't see it.

With that disconnected, if you still don't have spark then it's time to get it hooked to a dva tester - the only sure way to confirm the stator and trigger are working properly.

I wouldn't totally discount the switchbox, but these are very very durable - but still could be the problem."
 
"Thanks Graham,
Ill check out

"Thanks Graham,
Ill check out those wires tomorrow and post what I find. Are the wires in the same locations on the remote controlled model? Because this is one. Is the 2 killswitches on these models the toggle under the key and the key? What is a DVA tester and where would i go to find one or have someone check it?"
 
"Yes, wires are same in the re

"Yes, wires are same in the remote model - when the tiller is removed the key switch harness takes the bullet connector for the second kill switch.

A DVA tester (and can't remember exactly what DVA stands for) will give you a peak voltage reading from stators and triggers.

A normal meter can not read/display the voltage correctly. In the case of the trigger, it produces a very short (maybe 1/100th of a second) AC "pulse" that it sends to tell the switchbox to fire cylinder 1 or 2 or whatever.

The DVA (or adapter) captures that peak voltage and kinda "remembers" what it was - displaying it on the meter.

It is a pretty nice device - way back you had to capture the "peak" on a "persistance scope" that kinda put a glow in the dark image on a little screen - but it faded quickly and had to be measured by hand - technology is nice now


Anyhow, a motorcycle shop or outboard shop will have a DVA tester - takes about 5 minutes to get results."
 
Well I finally got ahold of th

Well I finally got ahold of the guy who ran the old mercury dealership where this motor was bought. I had the stator and trigger off figuring they would be able to test it off the motor but the guy told me it had to be on it and turning the motor over to test it. Im gonna put it back together and take it back to test it out. Ill update then. Thanks
 
I got the stator and trigger t

I got the stator and trigger tested today. Was told it tested good. I havent got to pulling the wire yet but that is my next step. If I have no spark then Ill be looking for a switchbox. Does anyone know anywhere online where used ones can be bought? Or where is the cheapest place to buy one?
 
Rapar makes a better than stoc

Rapar makes a better than stock one. EBay is a good source for used ones.

Jeff
 
"A used one is a good option i

"A used one is a good option if you can find one. These, in general, are very durable.

In fact all the ignition components off of a 1986-on 6, 8, 9.9 and 15 horse are completely interchangable and really don't break all that often - so used parts still can be a little pricey."
 
"I got a used switch box today

"I got a used switch box today off a 96 motor that scattered for $50. Took it home and put it on, and I now have spark. So, I went and hooked the fuel up to test out the water pump. I hooked up the muffs on what I think are the inlets ( little hole on each side on the underside of lower unit?) and have no water coming out of the rubber hose coming out of the case. Then thinking maybe that isnt where it takes on water, I just put a garbage can under it and filled it, and still no water. Does this mean I need a new water pump? Or is something clogged or thermostat bad? How involved of a job is changing the water pump for an unfamiliar mechanic? Another thing, While its running it smokes out the exhaust like a chimney, filled my whole yard and drive after about 30secs of running. Is this normal for setting so long? Could my gas mixture be to rich (I believe its mixed 32-1) or could there be a more serious problem? It ran fine, started right up, no missing, seemed ok running wise. What mixure should the gas be mixed?"
 
"Do the waterpump and run it m

"Do the waterpump and run it mixed at 50:1

The water intake is under the cavitation plate (above the prop) - kinda rectangle with a screen on it.

Unless someone added a thermostat it won't have one. The cover is there and the motor can take one, but Merc shipped these from the factory without one."
 
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