Only 2 of 4 coils gives a good spark.

[ixs]

Hello
This will be the .third bad year with a faulty engine.
I feel like slowly sinking it in the deepest part of .....
Finaly I found that I lose the spark when the rpm get higher.
It will jump easy more than ?" (10-15 mm) at tick-over (idling)
When increesing the revs to approx 2000, number 1 and 2 will only jump
1/8" (3-4 mm)
Changed two coils, but it did not help.
Stato or berbolt 50hpox, or trigger.
But how test without taking the flywheel of, and its in water.
#1 Thunderbolt 500 50hp Belgium made 9108090 1976 no distribuator

 

[achris]

Re: Only 2 of 4 coils gives a good spark.

You need to build a DVA for your multimeter. You are most fortunate, as someone has done the work for you and produced instructions.

http://forums.iboats.com/showthread.php?t=374544

Then you can use that to check if the stator is failing as the speed gets up. If the stator is ok, then replace the switchbox.

Chris............

 

[ixs]

Re: Only 2 of 4 coils gives a good spark.

Hi
I finally made my DVA meter. According to this diagram
http://forums.iboats.com/showthread.php?t=374544
Measured my cables, and obtained the following values.

The problem during the last two years, is that the engine been sick. Very sick.
No revs, no speed.
Earlier jobs
Changed the lower sealbox crankshaft, Gaskets changed on the carburetor, Fuelpump, etc.
etc..
Eventually discovered that the two coils did not give a spark when the engine speed increased over1500 rpm

Measurement between cable from box to the coil and earth.
Idling/High speed
Green/Black 254/260
Green/Red 253/260
Green/White 190/106
Green 190/103

Measurement of red and red/white from the stator
Plus on red/white
Idling/High speed
135/230
Minus on red/white
90/230

Measuring between blue and blue/white from the stator
Plus on blue/white
Idling/High speed
260/300
Minus on blue / white
300/270

DVA-measurement on the trigger wires got around 8V
Then the question is, what does this tell me?

 

[Dave1027]

Re: Only 2 of 4 coils gives a good spark.

Have you tried replacing the switchbox? That's what it sounds like the problem is.

 

[ixs]

Re: Only 2 of 4 coils gives a good spark.

YEEEEEES!!!!!!!!
Changed the box. And now it flies like a rocket.

 

[ixs]

Re: Only 2 of 4 coils gives a good spark.

Hi
Works very good, 30 knots.
But after two weeks. Some b*s*t*a*d stole the engine.