Tachometer not working correctly after voltage regulators installed. o

[bobdec]

I have a 1996 Mercury 150 HP model 150XL serial 0G337407 . Had intermittent problem of voltage jumping up to 16-17 volts, so I replaced the two (2) 815279-4 regulators with two Caltric e-bay units with the black ground wire. After that the voltage was solid at 14.1 volts running, but the tachometer was not reading correctly. It reads 1200 RPM at idle, when I can tell it's correctly running at the 700 idle I have it set to, when increasing RPM in neutral the tachometer climbs to 2000 and then just dies and goes to 0 . After engine RPM drops back it then goes back to 1200 at idle. I checked wiring connections multiple times, also the black ground regulator terminals are on one of the regulator mounting studs (same plate as the coil grounds). I switched the gray tach wire to the other regulator and the tach had the same exact error symptoms. I then put one of the old regulators back in. hooked tach to it and it worked perfectly. Looks like the Caltric units are giving incorrect signal... Any one ever heard of this.. almost sounds like a tachometer setting is needed, but the reg is supposed to be a direct replacement.

Here's a link http://www.ebay.com/itm/271170806219?_trksid=p2059210.m2749.l2649&ssPageName=STRK:MEBIDX:IT

 

[Chris1956]

Bob, You could connect the tach signal wire to any of the yellow stator wires. I would recommend you create a bullet Y connector to install inline, between the stator wire and the VR wire, as you do not want to blow any of the diodes in the VRs..

 

[Dukedog]

I checked wiring connections multiple times, also the black ground regulator terminals are on one of the regulator mounting studs (same plate as the coil grounds). I switched the gray tach wire to the other regulator and the tach had the same exact error symptoms. I then put one of the old regulators back in. hooked tach to it and it worked perfectly. Looks like the Caltric units are giving incorrect signal... Any one ever heard of this.. almost sounds like a tachometer setting is needed, but the reg is supposed to be a direct replacement.]

I'd give 'em a call or email. Pretty evident it not a "direct replacement" or its defective..... That's pretty cheap compared ta tha rest. Aftermarket and oem.

 

[bobdec]

I was going to put my oscilloscope on the grey wires of the Cartric's and compare the signals to the OEM regulators, but I just decided it was not worth the time. Maybe it just could be the tach in my ProLine is sensitive to types/levels of input. Caltric does not have phone support, I emailed them and the response was " they should work, if not then return them for credit ". So after paying shipping for purchase and now the return, plus wasting a couple of hours messing around. I decided I don't want them on my engine.. The units were really generic looking, absolutely no numbers or identification on them. Looked like a low cost knockoff product, that's my opinion not based on any facts..

 

[Chris1956]

I used CDI brand VRs on my '93 Merc 135HPV6. The Tach works fine, and the motor keeps the battery charged.

Ironically, the voltage jumps up and down quickly, with the engine running at idle, when I measure it with my digital multimeter. Not sure why that is....

 

[bobdec]

I see CDI's replacement for $150.00 so it must be a better designed unit than Caltric's $35.00 . At low RPM (idle) my alternator output is pretty low at 700 RPM and I notice voltage varies whenever I use any power like tabs or trim at idle. My voltage runs a bit over 12 volts at idle after start up on a discharged battery, but climbs back to 14.1 at idle when the battery is charged up. Power draws at idle (tabs,pump, trim) are more noticeable on my volt meter, may actually drop below 12V . But that all goes away over 2000 RPM and the voltage then stays pretty steady at 14.1. I wonder if these regulators have just have a simple on/off/stepping charge rate and maybe yours is just switching to different charging (voltage) levels as the load varies. I have two batteries, a cranking and a deep cell on a 2-way switch, the voltage levels characteristics are about the same on each.

 

[Chris1956]

Bob, I would think the current rates required on my boat at idle are minimal and steady, as the boat is only recharging the battery at idle. Maybe as the stator spins and provides voltage to switchboxes, the voltages in the charging coils vary slow enough to be read by the digital voltmeter?

Just a guess, as my knowledge of electrical engineering just went off a cliff, with this issue. Maybe an analog meter would give a steady RMS-like reading?