So I thought I would start a thread about my current issue. I have a 1980 Mercury 115 inline on the back of my 1990 SeaRay that won't run. When I picked the boat up, the owner fired it up (after the engine lugging from what sounded like a dead battery and a jump from my truck) and it sounded great. Get it home, and now it won't run. After some reading on the wiring diagrams, I found a few issues with the PO's or PPO's wiring. First off, they had a wire running from the positive terminal of the battery to a ground on the boat and none of my gauges or radio would work. Fixed that and put correct terminals on and voila, everything else on the boat works now. Then they have a wire running off the mercury switch plus 1 wire off each ignition box running to the gray harness wire, when according to the diagram the black/yellow wire should be connected to all of these and the gray wire should run to the rectifier. Here is a few pics:
You see in this pic, the gray wire is connected to a wire from the mercury switch, one from the top ignition box and one from the lower:
Here's the Mercury Switch, the black/yellow wire was connected to this switch via a green wire, then a green wire ran off this switch to the bundle connected to the gray wire:
And a pic of the rectifier:
I hooked the black/yellow wire to the ones running from the mercury switch and ignition boxes and used a jumper from the gray wire to the rectifier to do some testing. Motor spins over great, won't fire. I pulled the #3 and #4 plug to test for spark (figured if only one ignition box was bad one of them would work). Held the plug against the block, nothing. So it seems like I have zero spark. I tested the black/yellow wire and it seems grounded (didn't get continuity to ground but if I used it as my ground on my meter it worked), so I tried disconnecting the black/yellow wire from that bundle and ran power to it to see if she'd fire, nothing. Can someone point me in a good direction? Am I doing these tests right? This is my first Mercury and other than your typical maintenance and some carb/fuel pump rebuilds, this is my first extensive boat motor project. I also put my leads on the ignition coils while cranking and I got negative volts, weird huh? And yes, I had the leads hooked up correctly.
You see in this pic, the gray wire is connected to a wire from the mercury switch, one from the top ignition box and one from the lower:
Here's the Mercury Switch, the black/yellow wire was connected to this switch via a green wire, then a green wire ran off this switch to the bundle connected to the gray wire:
And a pic of the rectifier:
I hooked the black/yellow wire to the ones running from the mercury switch and ignition boxes and used a jumper from the gray wire to the rectifier to do some testing. Motor spins over great, won't fire. I pulled the #3 and #4 plug to test for spark (figured if only one ignition box was bad one of them would work). Held the plug against the block, nothing. So it seems like I have zero spark. I tested the black/yellow wire and it seems grounded (didn't get continuity to ground but if I used it as my ground on my meter it worked), so I tried disconnecting the black/yellow wire from that bundle and ran power to it to see if she'd fire, nothing. Can someone point me in a good direction? Am I doing these tests right? This is my first Mercury and other than your typical maintenance and some carb/fuel pump rebuilds, this is my first extensive boat motor project. I also put my leads on the ignition coils while cranking and I got negative volts, weird huh? And yes, I had the leads hooked up correctly.