1984 Mariner V-150 spark issues

[archcycle]

A family member just gave me a boat with a 1984 Mariner V-150 s/n 6533174. I've run it before but it's basically been in disuse for several years with the last time it was on the water over a year ago. Now it's got some problems from sitting around in a driveway for ages. I haven't gotten a service manual for it yet and I think the one I need is 90-97658 but would appreciate confirmation. I just got it and am on vacation for the next 4 days and would like to see it moving before I go back to work.

Here's what I know so far-
compression 120 across the board
last year impeller replaced and oil pump disconnected because of several issues with it by a reputable shop
port side sparks great
starboard side intermittent spark issues

The #5 coil was very rotten so I replaced it and the plug wire broke so I replaced that too and #5 started sparking across a good gap on the spark tester. I got power output on a DVA on all cylinders in/out from the starboard powerpack and then checked the other coils with the new plug wire and they sparked. The next day I went back to it and now it's not sparking on the entire starboard bank again even though it's got voltage at the powerpack.

Can someone help me out with the next step here? I've got a powerpack with voltage, a brand new coil, a brand new wire, and no spark. There have been some rotten wires like the hot going into the SB powerpack that were really far gone that I replaced with correctly gauged replacements so its possible that there's just another rotten wire in there that has gotten banged around with all the troubleshooting but so far without the service manual it's been just shooting blind with the voltmeter.

 

[Dukedog]

Re: 1984 Mariner V-150 spark issues

Probably stator, switch box or both. Also rotten wires on stator, trigger that are not visible. Its old and sittin' around was not good for those electrics. They are notorious for rotten wire. If you plan on using it I think you would be ahead by replacing stator, trigger, and both switch boxes............jmo

 

[archcycle]

Re: 1984 Mariner V-150 spark issues

The factory service manual came in the other week and the trigger failed every resistance test, showing no continuity on all tests, but I don't have a whole lot of faith in resistance tests. Especially when the part seems to work.

It didn't have any troubleshooting for the switch boxes but swapping those got great sparks on the starboard side and moved the same problems over to the port side so I replaced it and now all 6 have a good spark.

The plug wires were very rotten and several broke trying to get them out and I had to re-engineer them a bit but the new set arrived yesterday so this weekend I'll get to drop it in the water and see how everything goes.

Anyone have thoughts on that trigger?

edit: my brother replaced the stator a few years ago and probably about 20 motor hours ago. the resistance tests were a little off from the manual specs but he doesn't remember if it was an OEM part and all of them tested right about the same so I'm willing to call that fine.

 

[archcycle]

Re: 1984 Mariner V-150 spark issues

Siphoned out as much of the old gas as I could and put a whole bottle of seafoam and some Stabil marine ethanol treatment in there and filled with fresh gas.

I put it in the water today and it first wouldn't go over 3000rpm. It's definitely not getting power out of all 6 cylinders and I know I have the spark issue fixed so I guess the carbs could be clogged unless there's a rev limiter function of some kind that's holding it back. It was definitely cooling so there's no overheat issue. Any sensors with rev limiters I might look at before tearing down the carbs?