Mercruiser 3.0/120 Backfire now No Fire

[ScooterMcTavish]

Hi All,

My brother bought my 85 Glasstream with a Mercruiser 120 and took it up to his lake yesterday. I had last used it two weeks ago, and the boat ran 100%. However, before selling it, I had to have a leak at a cracked bellows (ouch) and a throttle cable repaired. Let's just say I lost close to a grand on the boat, but my nephews will be riding in it, and my brother is not mechanically inclined. At least I can sleep at night.

Regardless, this worked out as I almost expected. After towing the boat for 200 mi down some pretty bumpy roads, he didn't pretrip the boat before taking it out on the lake. So after running well for a few minutes, he loses two spark plug cables, one off the distributor, and one off a spark plug. Of course the boat then backfires (probably arced a spark), and now he can't get it to start.

I'm guessing he may have cooked at least 1 (if not both) wires. He could have also cooked the distributor/rotor, and the coil.

What say you all. Or could something worse have happened?

 

[Scott Danforth]

probably fouled the two plugs. I would pull the plugs, take a look. recheck the wires, check the dwell, and timing.

would probably suggest a set of wires and a new cap and rotor and points while you are at it.

 

[Fishermark]

...So after running well for a few minutes, he loses two spark plug cables, one off the distributor, and one off a spark plug. /QUOTE]

How do you lose two spark plug cables? I take it you mean they fell off? A bumpy road would not cause them to fall off unless they were not put on completely.

Regardless, I would suggest new cables and double checking the firing order. (1-3-4-2).

 

[ScooterMcTavish]

Well, he's taken it to the boat doctor, so I'm sure he'll get set up well anyways.

When I changed the plugs this spring, all of the cables were seated firmly, so I have no idea how they got off other than his explanation. The same thought occurred to me too, but when it was in the shop before his pickup, all it had was throttle cable/bellows repair. No reason to touch the wires.

Based on a phone call, it sounds like he had the firing order right. Should note that one lead fell off the distributor, and one fell off a plug, so really no way to mix them up.

Very odd in general, I agree.