90hp mercury fuse/rectifier problem

[Texasmark]

On the two red wires, they are different sizes....not in front of me so I can't give you the AWGs. My bet is that the small one is for housekeeping voltages to the regulator and the other larger one is 0-16A (Red Stator) output for battery charging.

Sam, your picture is ok except on these1998 and later engines there is no separate terminal block....the solenoid stud is the TB.

Looks like we are all in agreement.....battery gets a look first.

Still can't figure out a connection to RPMs and the fuse blowing, unless you are pumping the Up trim switch ensuring trim stays in max up.....to get your expected top speed. Butttt that's just solenoid control current, no way near 20 amps.........."Gremlins".

 

[georgia088]

No trim is necessary to blow the fuse. WOT blows fuse with no accessories on and no trim used. I could check the resistance on the switch (not exactly sure if I am just checking for direct short or if there is some chart with ohm readings on it?), but in my mind, nothing within the switch could cause it to only blow at WOT. I will change batteries (hopefully this weekend) and report back either way. Thanks again!

 

[Faztbullet]

You say your going to change batteries(as in two)....Do you have this wired to dual batteries? Do you have a battery selector switch installed?

 

[georgia088]

You say your going to change batteries(as in two)....Do you have this wired to dual batteries? Do you have a battery selector switch installed?

No, I only have one battery. I do have a battery on/off switch, but it only cuts the main power off from the one battery.

Thanks.

 

[Texasmark]

No trim is necessary to blow the fuse. WOT blows fuse with no accessories on and no trim used. I could check the resistance on the switch (not exactly sure if I am just checking for direct short or if there is some chart with ohm readings on it?), but in my mind, nothing within the switch could cause it to only blow at WOT. I will change batteries (hopefully this weekend) and report back either way. Thanks again!

Ahhhhhhhhhhhhh. I think you just inadvertently nailed it. The switch consists of silver semi-circles embossed in a phenolic or other dielectric substance for retention. Back side of the substrate/substance is where the pinout is for connecting the wires. There are printed circuits between the dots where needed and the wiper may or may not pass over them...not an issue.

The silver material of which both connecting surfaces consist, over time, makes a conducting path between terminals and can cause short circuits within the switch....moisture and foreign objects like dirt and salt corrosion can hasten the problem.

Buttttttt the switch isn't the problem. The control box has a "hot" wire binding on/pinched by the moving part of the shifter/throttle control. The only place touching occurs is when the throttle is wide open and that's intermittent as it also takes the boat bouncing up and down on the waves to make contact. So line up the control, add the vibration, wait for the right moment and bingo.

Next step, after you get the battery question solved, is to open the remote control and carefully inspect the wiring for insulation worn off that could contact metal as a result of the control set to the WOT position. Red, Red/purple stripe, or purple would be your first thoughts in pursuing your investigation.

What else makes sense????????

 

[sam am I]

If the control box metal guts are grounded (usually sorta are due to linkage), this certainly could be the case BUT, the fuse would (normally?) be vaporizing if a trim switch power feed wire in the box was shorting to ground.

Was thinking also to test this possibility (when and if) , he could also just disconnect that power feed instead of dismantling the thing.....Could set the trim in, disconnect power, would certainly be fine to just do a test run w/o trim.

 

[georgia088]

Ahhhhhhhhhhhhh. I think you just inadvertently nailed it. The switch consists of silver semi-circles embossed in a phenolic or other dielectric substance for retention. Back side of the substrate/substance is where the pinout is for connecting the wires. There are printed circuits between the dots where needed and the wiper may or may not pass over them...not an issue.

The silver material of which both connecting surfaces consist, over time, makes a conducting path between terminals and can cause short circuits within the switch....moisture and foreign objects like dirt and salt corrosion can hasten the problem.

Buttttttt the switch isn't the problem. The control box has a "hot" wire binding on/pinched by the moving part of the shifter/throttle control. The only place touching occurs is when the throttle is wide open and that's intermittent as it also takes the boat bouncing up and down on the waves to make contact. So line up the control, add the vibration, wait for the right moment and bingo.

Next step, after you get the battery question solved, is to open the remote control and carefully inspect the wiring for insulation worn off that could contact metal as a result of the control set to the WOT position. Red, Red/purple stripe, or purple would be your first thoughts in pursuing your investigation.

What else makes sense????????

This is similar to the battery on/off switch that I have. https://www.ebay.com/i/202496607440?chn=ps&mkevt=1&mkcid=28

I assume you are talking about the ignition switch on the dash? As far as the wires inside the f/r throttle controller, I have not taken the throttle apart, but I have turned the ignition switch to the on position and pushed the throttle all the way to WOT and "wiggled" it to try and recreate the fuse blowing. I have done this several times and haven't been able to do it. Obviously, it could be that I am not able to recreate what a moving boat would do though. Its weird that the fuse always seems to blow about 45 seconds-1 and half minutes of going to WOT. Smooth water, rough water, doesn't seem to matter. Also, this engine has never been around salt water. It does stay in a fresh water lake year round under a covered boat dock. (trying to give as much info as possible.) Thanks again!

 

[georgia088]

If the control box metal guts are grounded (usually sorta are due to linkage), this certainly could be the case BUT, the fuse would (normally?) be vaporizing if a trim switch power feed wire in the box was shorting to ground.

Was thinking also to test this possibility (when and if) , he could also just disconnect that power feed instead of dismantling the thing.....Could set the trim in, disconnect power, would certainly be fine to just do a test run w/o trim.

This seems to be an easy test I can do. Can you tell me which wire to disconnect to disable the trim and test?

 

[sam am I]

Well depends on your control box of course but, generally speaking if you have a simple side mount console type or the like, the trim switch has a cable leading into the box, should be a connector you can just unplug........see below as an example.

 

[Texasmark]

".......the fuse always seems to blow about 45 seconds-1 and half minutes of going to WOT." This is indicative of a load that is slightly above the rating of the fuse....so you are sucking 20-25 amps. A moderate to low resistance and the length of your cabling to and from the engine, 14 AWG wire assumed, could do that.

My reference was to the Mercury'Quicksilver side mount Commander 2000 or 3000 to name a couple that have everything within the control. With your switch being dash mounted, that eliminates several wires that could be damaged within the box. That could still leave the trim power as I see a trim button on your handle.

Going to guess the wire out the rear is for an alarm transducer within the control....what else could it be. The front wire, coming out where it does seems to have a barely visible red on the left, green on the right ...assuming blue in the center meaning this is your trim power. Looking at the location of the exit point, and the control lever adjacent to it, I would say that this could be your smoking gun. Well worth your time to disassemble and investigate.......quick answer would be to quickly get up to your WOT speed and immediately unplug it, before the fuse has had time to blow....seems you can do that.

 

[Faztbullet]

Bypass the battery selector switch...seen loose/bad internal connection cause all sort of gremlin problems..

 

[georgia088]

I wasn’t able to run the boat this weekend, but my dad was. He didn’t get to run it much, but this is where we’re at....

This is what he did. Put brand new battery in. The fuse still blew. Bypassed battery selector. Still blew. thought he unplugged trim (he unplugged yellow wires coming out of Back) the fuse still blew. Unplugged stator from under cowl, ran it WOT 5-10 minutes. Fuse didn’t blow. Rectifier still working. So, he connected it back and ran the same distance. Back with stator connected.... fuse didn’t blow.... go figure. Started raining; so that’s where we are for now. Thoughts?

thanks again!

 

[Texasmark]

Corrosion in fittings you touched. When you said you disconnected the stator, what color were the wires....green with white or a pair of yellow?

 

[georgia088]

Corrosion in fittings you touched. When you said you disconnected the stator, what color were the wires....green with white or a pair of yellow?

He says he thinks it was yellow. I have unplugged and plugged all the wires in several times to try and eliminate any bad connections.

 

[sam am I]

Unplugged stator from under cowl, ran it WOT 5-10 minutes. Fuse didn’t blow. Rectifier still working. So, he connected it back and ran the same distance.

Not sure I understand..........If you unplugged the stator, the rectifier has to stop working (outputting charge voltage) at that instant because the stator's charge winding feeds it, right?

Maybe you meant "still working" as in it didn't literally blow up? Which it shouldn't.......

Anyway, dis-connecting the stator stopped the fuse from blowing, then reconnecting it and now life is good? So an "upstream" issue!!

So yeah, as TM and FB said, flaky connections can cause weird things to happen. Perhaps the poor connection caused the rec/reg to lose regulation and thus, the output voltage was excessive?

However, what I find odd is didn't you say you replaced these specific items back in post #1? Then went back to the original part again? This (I would think) w/should have had you connecting and re-connecting several times those same exact connections your dad just did? Hmmmm, dad has the magic touch?

As mentioned earlier, if too high of charge voltage is applied to a battery, it will always draw excessive current. That current, in our case, WILL(has to) flow through the main fuse as the rec/reg is the excessive voltage source BUT, we should see this on a volt meter.

Does your boat has a volt meter on the dash? Might have been jumping waaay up, like in the 16++ volt range..

 

[georgia088]

Not sure I understand..........If you unplugged the stator, the rectifier has to stop working (outputting charge voltage) at that instant because the stator's charge winding feeds it, right?

Maybe you meant "still working" as in it didn't literally blow up? Which it shouldn't.......

Anyway, dis-connecting the stator stopped the fuse from blowing, then reconnecting it and now life is good? So an "upstream" issue!!

So yeah, as TM and FB said, flaky connections can cause weird things to happen. Perhaps the poor connection caused the rec/reg to lose regulation and thus, the output voltage was excessive?

However, what I find odd is didn't you say you replaced these specific items back in post #1? Then went back to the original part again? This (I would think) w/should have had you connecting and re-connecting several times those same exact connections your dad just did? Hmmmm, dad has the magic touch?

As mentioned earlier, if too high of charge voltage is applied to a battery, it will always draw excessive current. That current, in our case, WILL(has to) flow through the main fuse as the rec/reg is the excessive voltage source BUT, we should see this on a volt meter.

Does your boat has a volt meter on the dash? Might have been jumping waaay up, like in the 16++ volt range..

Yea, my post was unclear. When the stator was unplugged the rectifier wasn’t working. But the fuse didn’t blow either. Plugged the stator back up and fuse didn’t blow and rectifier worked, and it didn’t burn up like the previous one did... so maybe problem was in connections??? But, with my luck I doubt it.

yes, I do have voltage meter on fish finder. It has always read 12.7-14.1v. I’ve never seen it spike high.

 

[sam am I]

Yea, my post was unclear. When the stator was unplugged the rectifier wasn’t working. But the fuse didn’t blow either. Plugged the stator back up and fuse didn’t blow and rectifier worked, and it didn’t burn up like the previous one did... so maybe problem was in connections??? But, with my luck I doubt it.

yes, I do have voltage meter on fish finder. It has always read 12.7-14.1v. I’ve never seen it spike high.

No worries.....and yes, maybe with some luck you did. However as you know, you can wish in one hand and.....well, you know the rest? HOWEVER.............

The sample/update rate on the fish finder's voltmeter might not have allowed you to see the voltage increases/decreases (spiking)if they were quicker in nature. Usually, connection issues(like maybe yours) "make and break" (spikes) rapidly as the temperature at the junction point increases (breaks) and decreases(makes) so fast, it's hard to see w/o a analog meter or scope.

 

[georgia088]

I know this is an old thread, but it is my old thread and my problem is related to the same boat/issue. So, if you read all the info in this thread, you will see that I was having issues with the main 20 amp fuse under the cowl blowing. I think it was related to the charging system, but not sure.
The fuse was blowing at WOT. I’m not sure why, and still don’t know, but it stopped....

Fast forward 6ish months and now my charging system is not working. The voltage on fish finder doesn’t change at all when boat is cranked vs off. Or, when you increase rpms. It stays around 12.1 v no matter what unless an accessory is on and it will drop below 12v.
I had two reg/rectifiers, so I put the new aftermarket one I ordered before when I was blowing fuses off and put the old one back on. No change. Still not charging.
Any ideas? How do you test if the reg/rectifier is getting the correct input voltage (I assume this comes from stator?)?
Thanks!

 

[Texasmark]

16 Amp Red Stator: Restance between yellow wires at 25C is between 0.16 and 0.19 Ohms...don't forget to touch the leads together to measure the lead resistance...on my meter it's 0.4 ohms so my readings would be between .56 and .59 ohms. Both leads infinite resistance to engine block...ground.

Black 16 Amp is 0.1 to 0.5 Ohms. Only other test listed in the Serv. Man. is a current test and skipping through it:
Idle Amperes: 2.5
2k RPM 16
5k 17.5
It didn't define the voltge nor the load. So I would guess you get a carbon pile, like is used in a battery load tester (Harbor Freight sells them for about $60) and contains an ammeter and voltmeter...you will need a separate low current ammeter...auto parts store for that.....wired in series with the negative lead between the stator and the test set.....the scale on the test set is for battery load testing....100's of amps is the reason.

Since that meter is designed for DC voltage, connect it at the large red wire outputfrom the Rect-regl output, with nothing else attached to that lead....black lead to Reg-rect ground...engine block...batt - terminal.
Crank engine and run at idle and then I'd crank the load for 2.5 amps and check the voltmeter on the instrument for 13 or VDC. With that resistance set, I'd leave the resistance of the pile alone and just concentrate on the amperage. If you go back and check voltage at the highest RPMs it should be up around 14.5 VDC.

If you do much mechanic work, or have a lot of things with batteries around your place...or your neighbors, you'd be surprised how handy it is to have that battery load checker handy....you aren't wasting your money on buying it. It's a real troubleshooting tool for batteries and their maintainers.