1982 150HP - No spark on #5 and #2

[ratlsnaktj]

Yesterday I started up the engine for the first time in a couple months and it sounded a flat and wasn't too happy to throttle up (in gear or neutral rev). I checked the plugs and they all looked good. Next I checked for spark on each cylinder and found #2 and #5 are not getting spark. I'm thinking it might be ignition coils, but I know the trigger coils are in pairs. Are these two cylinders on the same trigger coil? Any recommendations on where to go with this next? Thanks for the help

 

[achris]

Re: 1982 150HP - No spark on #5 and #2

Yes, those 2 cylinders are on the same trigger coil... So the problem could be the trigger, or it could still be one of the switchboxes. Remove the 2 trigger wires and check the resistance of the trigger coil. Then check a good one, either 1 and 4, or 3 and 6... If they are look good, then one of the switchboxes is probably guilty...

Chris.........

 

[ratlsnaktj]

Re: 1982 150HP - No spark on #5 and #2

Chris,

If it was one of the switchboxes shouldn't an entire bank be not sparking? And just to confirm we're on the same page... standing behind the boat, looking towards the bow... cylinders on left are 1-3-5 and cylinders on right are 2-4-6 top to bottom.

 

[achris]

Re: 1982 150HP - No spark on #5 and #2

If it were the SCR or capacitor in the switchbox, then yes, it would kill the whole bank. But if it's a trigger steering diode (1 in each switchbox for each trigger), then only the 2 cylinders associated with that trigger pair would be affected. So, if the trigger coil tests don't find a fault, then one or other of the switchboxes could be the problem.... I'm 5,000 miles from my manuals so I can't post a circuit drawing of the switchbox. If I could you'd see what I mean straight away...

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