40 HP merc 2 Cyl only hitting on one.

[littlepoopers]

Hi All, I'm new to the forum. My 1981 Merc engine is only running on one cylinder. We've checked the stator and coils with an Ohm meter and they check out OK. What does the trigger do, and how do I check it? I also need to know how to check the Switch box. We switched the coils and the same cylinder runs, so I know the coils are OK. Any help will be greatly appreciated.
Thanks.

 

[turtles11756]

Re: 40 HP merc 2 Cyl only hitting on one.

i'm sitting here looking over at a mid 70's merc 402 (40hp) with a new cdi switch box , a new old stock trigger, the original trigger which was repaired, a new stator and still only spark on one cylinder so i can't help you except that the trigger sends the signal to fire to the switch box. someday i'm gonna get the darn thing to fire on both the only thing left is the inner flywheel magnets

 

[verado7]

Re: 40 HP merc 2 Cyl only hitting on one.

reverse the stator input wires on the switchbox -if the spark moved to the dead cylinder - the switchbox is bad . resistance tests are just the first test to do because its quicker and if you find a fault there no need for a longer test -but they aren't to be relied upon for finding ignition problems - what you need is to get a dva adapter -sold here at iboats , cdi electronics and ebay - ( about 70 dollars ) this will allow you to read the actual voltage at each part - however there are a few tricks like teh one i mentioned at the top of the page -its teh first thing i try when a motor looses 1 cyl. or 2cyl. ( on a 4cyl. model) .

 

[littlepoopers]

Re: 40 HP merc 2 Cyl only hitting on one.

Thanks fellas. I've ordered a DVA testor and will check hot numbers. It checks out ok with an Ohm meter. Thanks again.