1988 merc 150 hp black max fire

[rikoshaprl]

The end of last season my shunt voltage regulator started a fire on my engine. Fortunately I had a fire extinguisher and put it out. Lots of wiring was burnt. I changed the shunt voltage regulator and idler box. Replaced all burnt wires to three coils on one side. Turns out the stator, one switchbox, and one coil were also damaged . Replaced them. I changed the trigger while I had it open. Also the rectifier for the hell of it.
My question is how do I stop this from happening again? Am I missing some fuse protection somewhere. I have the manual and don't see anything wrong.
PS this forum has been a great help!

 

[j_martin]

Re: 1988 merc 150 hp black max fire

The end of last season my shunt voltage regulator started a fire on my engine. Fortunately I had a fire extinguisher and put it out. Lots of wiring was burnt. I changed the shunt voltage regulator and idler box. Replaced all burnt wires to three coils on one side. Turns out the stator, one switchbox, and one coil were also damaged . Replaced them. I changed the trigger while I had it open. Also the rectifier for the hell of it.
My question is how do I stop this from happening again? Am I missing some fuse protection somewhere. I have the manual and don't see anything wrong.
PS this forum has been a great help!

The rectifier output goes straight to the battery terminal on the solenoid. It wouldn't hurt to put a heavy duty ATO fuse holder in that wire and a 20 or 25 amp fuse.

Don't put the shunt regulator back on. It was such a bad idea you haven't been able to buy one new for years. The 16 amp charging system will slowly toast your battery if you don't use the power, like with livewells, or trimming a lot. Even then, with proper maintainance, a battery will last for 3 years.

If you want to do it the finess way, wire in a 20 amp regulator off'n a dual 40 system. It's TSR circuitry and runs pretty cool, especially if you get one of the later 6 wire ones.

I converted my XR4 to 40 amp. The flywheel cover won't go under the clamshell, but otherwise it fits. I'm looking for a later 1 piece XR4 cowl. I do some back country camping in the north woods, so I needed the extra juice to keep all the batteries up.

hope it helps
John

 

[rikoshaprl]

Re: 1988 merc 150 hp black max fire

Thanks John. There is an in line fuse. I thought it was strange that it didn't blow before the wiring etc. burned. The fuse comes directly from the battery. I'm guessing that once the engine is running, the current is being generated by the stator so that fuse is not really protecting anything.
Rick

 

[j_martin]

Re: 1988 merc 150 hp black max fire

Thanks John. There is an in line fuse. I thought it was strange that it didn't blow before the wiring etc. burned. The fuse comes directly from the battery. I'm guessing that once the engine is running, the current is being generated by the stator so that fuse is not really protecting anything.
Rick

I think the inline fuse goes to the trim. The rectifier connects directly to the solenoid, and also to the fire-starter, i mean regulator. The solenoid then goes directly to the battery. So the path from the battery to the regulator is not fused.

hope it helps
John

 

[rikoshaprl]

Re: 1988 merc 150 hp black max fire

Got it. That's why that son of a gun cost me $550.00! Thanks again.