1994 Mercury Black Max 135 on 200OVOB - No Charge

CNYBoater

Active Member
Aug 14, 2017
386
Boat Info
1994 200 Overnighter, Single Axle Easy Load'r Galvanized Trailer, 2006 Toyota Tacoma Double Cab
Engines
Single 1994 Mercury Black Max V135 O/B
I recently installed new gauges and noticed that my poor voltage readings carried into the new gauge, as well as all gauges dipping doing trim usage. I rewired the gauges with new marine tinned 14 gauge wire as the old non-tinned 16 gauge wires are just old, being a 1994 boat. changing the wires out, gained me a bit of reading, I'm assuming from less resistance and moving the voltmeter closer to the new ignition switch.

anyways... We were out today, and I noticed that the voltmeter was still reading around 12vdc at all RPMs. after an hour or so, we pulled up to a state ramp and tied off and sat in the shade for an hour or so having a picnic. It took 10 minutes and hooking the jump box up to refire the engine, voltage had dropped to around 11.5ish. When we docked up to trailer home, voltmeter was still reading just below 12vdc. On my old outboard, (1978 Johnson 115) I had to replace the rectifier twice. Looking up the parts catalog, it looks like this outboard uses 2 voltage regulars instead. They are rather pricing if I don't want to buy the knockoffs shipping from China. I don't want to risk them melting under the cowl nears god knows what flammable fumes.

So question time... There is a seller on eBay with new, old stock (stamp on the mercury VR unit is 1993) at a very resonable price... Should I buy both 20A rectifiers and replace them as a pair? Should I avoid the eBay old stock items, since these are electric components? CDI and Siera are a bit cheaper, but if I need to do a pair, I'm off the water for a while, as that will come out of my boating fuel budget. I've already spent my maint and upgrade budget for the year. At the moment, its frequent water level checks int he Exide 27MDP battery and put it on the charger at home. but that limits my anchor and restarts for a trip. Kids really wanted to anchor and inflate the lake lounger, but I didn't want to risk it.
 
Going to need to buy new bullet connectors, it melted the harness ends as well. There is some soot on the wires of the other voltage regular and a crack in the epoxy over the circuits but not melted. Ordered a second one to replace it just in case. Wondering if I should put heat shrink tubing over the wires as an added layer of protection from the heat of the block.
IMG_0588.JPG
 
I would…..but then I usually error to the side of caution as they say

The wiring harness is in a sleeve and there is no heat damage to that even though its on clips right next to the block. I couldn't find any identification on it though, so I don't know where to buy heat insulating tubing to put around the wires, if that's even what it is. I was thinking that I'd use long pieces of heat shrink tubing from the back of the regulator over the wire, connector and up to the harness. cover up the whole thing. dielectric grease inside the connectors of course.

I also bought a tube of silicone based heat-sink compound to put on the back of the voltage regulators when I mount them. There was a greasy burnt compound behind it, but it didn't look like thermal paste. I still don't know what toasted the regulators. I haven't disconnected the battery while engine was running, nor cross polaritied anything. Grounds look good, but are all covered in black liquid electrical tape, so I suppose I could disconnect them one at a time, scuff um up to shiny and reattach with a dab of dielectric over them instead of liquid electrical tape.

Sound like a good plan?
 
In most cases like that your trying to charge with too much current or too many batteries or too great of a load on the motors charging system.
What exactly is hooked up to the battery(s)
 
NorCal, I bought a SternMate and epoxied that to the transom, I’ve been out once since I installed it and it was good to about 30mph, then dashes, so I need to adjust the height a bit and try again, think it might be a little high.

As far as battery draw. I have a Exide 27MDF (marine dual purpose) with a perko on/off switch. Bulge pump is wired direct. I have a blue tooth radio, power trim, standard nav lights, horn and dash cluster. All but the temp gauge are new Fario Euro Gauges, speedometer is GPS not water pickup. Radio is a Pyle Bluetooth receiver no am/fm with two 6” speakers.
 
Should I look up the amp draw for each component and list them? When I purchased the boat, it had a group 24 starting battery. I removed the battery holder, filled the holes and upgraded to a group 27, MCA on it are well above the 350 minimum listed in the motor manual. Last year I had a problem with the starter, it'd turn but not spin up the bendex to the flywheel, even though battery charge was sufficient. I disassembled, cleaned the inner casing, windings and checked the brushes. No problems after that, though I don't know if it could have stressed the voltage regulators?

Disappointed in eBay sellers at this point. Second voltage regulator I bought for the questionable VR was DOA, one of the yellow wires was snipped off. Ordered an after market from a different seller in NJ, posted a tracking number in eBay days ago but USPS isn't showing it was dropped off. So much for having this fixed by the weekend.
 
Finally got the new voltage regulators in. Went to test Sunday, and at Idle, just over 12v, throttle up and I get a bit over 14v. Something is wrong though, since the Tach worked fine before I replaced the VR, and it was working with one VR blown and now I idle around 600 but no matter how much throttle I give her the engine spools up but tach is only showing in the 1000 range. Not time I'm at the boat, I'll try swapping the tach lead to the other VR, though I don't see how that should matter.
 

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