PDA

View Full Version : '87 merc ignition problem



MattM
02-03-2010, 11:15 PM
Hi,

Getting the boat out a little early this year and have no spark in the plug wires, but have spark in the coil wire. Can this only be the rotor and cap? thunderbolt ignition.

thanks for any help, Matt

MOP
02-04-2010, 06:39 AM
Do you have insulated pliers? If so take the coil wire out of the cap hold it about 1" from ground, if it jumps that gap repeatedly as the engine turns then my first shot would be a set of wires and cap & rotor. The Sierra cap & rotor are every bit as good as the merc parts at about 1/2 the $$, spend the saved $$ on good quality name brand wires. Wires go the heck a lot faster in our boats then many realize.

Phil

mrfixxall
02-04-2010, 09:46 AM
Hi,

Getting the boat out a little early this year and have no spark in the plug wires, but have spark in the coil wire. Can this only be the rotor and cap? thunderbolt ignition.

thanks for any help, Matt

Sounds like the rotor is firing to ground..pull the rotor and see if theirs a hole burnt in the center ..

silverghost
02-04-2010, 10:22 AM
Rotor & cap are the first things to look at.
Next would be all connections at ignition coil & keyswitch. Check engine grounds (-).
Next would be the ignition coil & finally plug wires.
If you have points & condenser, not Mercury. electronic ign. look there also.
With a boat of this age a good ignition tune-up might be in order .

thehow33
02-04-2010, 08:23 PM
Sounds like the rotor is firing to ground..pull the rotor and see if theirs a hole burnt in the center ..

I agree with Fix same thing happened to me on my Mustang...But right before that happened I had moisture getting inside the cap.