74 model 402 merc. 40hp not firing help please..

[zanhal]

I had this boat given to me, but it was a basket case.all the wiring was rotten.I rewired the internal harness,repaced stator,rectefier.........it spins over by key good.sounds strong.what next????? switch box? trigger coil,ign.coils.I'm a electrician but I do not know how to check this stuff. please somebody help me.

 

[12Footer]

Re: 74 model 402 merc. 40hp not firing help please..

<br />Hope this turns-out def enough to read.I don't think so.If not, Email me with Merc40HP wiring in the subject line,and I'll send you one you can blow up.<br />Off the head, disconnect the grounding lead from the stator (killl switch wire), and try it..One caution: Try not to ttouch the chassis when testing with this wire undone...It likes to shock you.

 

[petryshyn]

Re: 74 model 402 merc. 40hp not firing help please..

I'd highly recommend a manual for check CDI units. The red and blue wires coming from the stator supply high voltage(150-200v) to the switch box. A peak reading meter is required to measure this voltage as it is a very fast rising spike. There is also a trigger coil under the flywheel as well. The white and brown wires supply a small voltage (.3-.5v) to trigger the switch box at the appropriate times to fire the coils. This small voltage also required a peak reading meter.(although the values you get from a standard DVOM will be low, atleast they would verify the presence of some voltages)<br /><br />If these voltages are OK, and all the wiring is OK, and the kill circuit isn't shorted to ground, then I'd suspect the switch box. I guess there is also a chance of 2 coils being bad at the same time, but very unlikely....