Bypassing the Switchbox

"Hi guys, is it possible to do

"Hi guys, is it possible to do a bodged bypass of the switchbox, ie..couple of relays on the trigger, when the trigger pulses it activates the relay and allows the stator to power the coil,
I have tried every thing on this engine (2002 mercury 25hp seapro) and it will not spark/fire on No1 piston, compressions are good, it gets fuel, but no spark, going by the manual for testing the trigger, stator, they are ok, I dont want to spend £150 on a new switchbox if its not faulty.
This is a continueing problem from last year and I gave up on it over the winter, now its time for fixing it or using it as an expensive anchor, I have replaced all gaskets and seals, checked the carb and the reeds,
Without use a dva adapter, I used a multimeter to check voltage from the switchbox to the coils and there is voltage, but I dont know how much as the meter reading is all over the place, maybe thats why we use dva adapters, "

If you are only getting spark

If you are only getting spark on one of the two cylinders and you are getting voltage at the coils i would remove the ignitions leads and swap them over to see if no.1 fires and no.2 doesnt. It may be leads faulted? Also you are getting current from the switchbox to the coils but are you getting voltage out of the coil?

"Hi, That was the first thing

"Hi, That was the first thing I done was to swap the coils, still no spark, cant swap the spark plud leads as no1 is to short to reach no2, so I bought new leads, no change, still no spark at No1"

"Hi guys, I went out again to

"Hi guys, I went out again to try it, and I disconnect the switchbox wires to the coils and tested them the same as you would a spark plug (hold them to an earth and see if they spark), No1 wire (green/yellow) did not spark and No2 wire (green) did spark, so can I safely say its the switchbox at fault.

To replace the switchbox do I have to replace it with an identical part, or can I use a switchbox from another model ie 25XD or a Marathon.
I can get a switchbox for other 25HP models at half the price of my own.

cheers James"

"James if your switchbox has t

"James if your switchbox has the bullet style connectors (push to connect - merc part 339-7452A19) you can use any switchbox from a 25 horse and under motor (the 18's, 6/8/9.9 and 15 horse models use the same one as well).

If it has the nut connectors (connect to terminal on the switchbox - merc part number 339-7452A3) you can either find one of them or switch over to the more common bullet style connections with a bit altering on your part...."

"Hi Graham, Yes it the bullet

"Hi Graham, Yes it the bullet type connecters, part number is 855713A3 or 13A4, which is £134 + vat, or I can get a 7452A19 for £49 including vat.

Now for the last question, I was told if the switchbox goes faulty it was propably the stator that created the fault in the first place and its better to replace the stater as well as the switchbox, is this true.
cheers James"

"James, the answer to that one

"James, the answer to that one is "maybe". Maybe the stator started throwing irregular voltage and toasted the switchbox.

But if that were the case why did it only kill the capacitor on one side of the switch box and not the other (??) - but still can't rule it out.

The stator could be tested with a DVA adaptor. If you don't have one the cost is about the same as the new (cheaper) switchbox - so depends which way you want to go....."

"Hi graham, Cheers, I will buy

"Hi graham, Cheers, I will buy a new switchbox, if it goes faulty again then its a new switchbox and stator, that was the idea of the bodged bypass, to try and rule out the stator, I know myself it was a bit extreme.

cheers guys for all of your help, next time I am yourside of the pond, Beers are on me

James"