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DT40 mystery

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knightjohn

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"my 40hp runs a treat out of t

"my 40hp runs a treat out of the water but cannot seem to get revs up when under load (in water).
I've completely checked/cleaned fuel system inc. carby. Noticed top plug was clean and bottom plug was dirty, but both getting spark. Could electricals be problem ? Both cylinders have good compression. Is it possible electricals occasionally missfire under load ? What should I check next ?"
 
"A good ignition system should

"A good ignition system should be able to fire a gap of 7/16", you need to check for that first."
 
thats a pretty good gap but it

thats a pretty good gap but its a good idea.
I'll let you know what happens.
 
It really is not an idea.Ignit

It really is not an idea.Ignitions are made to fire such a gap because it is needed.
 
well the maximum gap my motor

well the maximum gap my motor can manage to spark is about 1/4" inch at best.
What do I check or replace now ? Is the solid state "coil" likely to be the fault or something like spark leads ? I wait for your further advise.
 
There really is no mystery her

There really is no mystery here.You can install new plugs.Swap the coils and see if the fouled plug shows up at the other cylinder.Then again you could use an inductive pick-up timing light to observe the behavior of the spark when you accelerate.Use it as a scope.Most motors run sort of " OK " when they have no load.
 
"okay, I'll post my result

"okay, I'll post my results. Incidently what should max rpm be for my motor and what should timing be set at (and at what rpm).
I'll check all these things and let you know."
 
Timing on outboard motors is &

Timing on outboard motors is " fixed " and unless someone has fooled with it it should be left alone.They are factory set and need no adjusting.
 
"today I tested spark under lo

"today I tested spark under load and spark definately misses when pressure is one. I guess you are right about CDI unit. In Australia these units are over $1,200 so are there any alternative ways of fixing the problem ? I have heard of guys repairing these black boxes and understand that the circuitry is fairly simple."
 
Do a search for ----browns poi

Do a search for ----browns point marine service------Look up the parts for your motor ( prices are there ) and send me a case of beer with the money you save.
 
year of my engine is 94. Could

year of my engine is 94. Could my problem be timing coil rather than CDI unit ? How can I test before spending a fortune on CDI unit ?
 
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