Rectifier location on 3cyl 90hp Mercury

"I'm having some electrica

"I'm having some electrical problems on a "new" old boat I just bought. This is my first boat and I'm still learning... It pops a starter motor fuse as soon as I connect it to the battery, I mean instantly. I checked and bought the right type fuses (SFE 20A) and replaced the solenoid, ignition switch and a voltage regulator--none of these things made a difference. I also bought a triangular/diamond shaped rectifier that is specked for the serial number, but I can't seem to find it anywhere on the engine... I have a generic SELOC repair manual for Mercury/Mariner engines but it does not show a physical location of it. Any idea where I might find it? The only place I haven't looked yet is under the flywheel it seems unless I'm staring right at it... can it be under the flywheel?

My Engine is 1995 Mercury Outboard, 2-stroke, 3-cyl, model# 90ELPTO.

Thanks in advance.
-Paul"

"remove the wiring plug from t

"remove the wiring plug from the engine, does it still pop the fuse? That 20 amp fuse is to power the accesories like the gauges, tach, depth finder and start relay. I dought the rectifier is the problem. Depending on the serial number, some have the rectifier and some have a alternator regulator. Here is a link, check out the different serial number and the electric picture
http://www.usboatsupply.com/Mercury_Mercruiser_Parts_Catalog3a.php?mc=01&ms=5830 &si=554"

"JB- thanks for your reply and

"JB- thanks for your reply and suggestions, I did in fact use these exact diagrams to purchase my parts except my serial #0G273410. link to diagram

So the diagram shows the rectifier #23 on their list as well as Voltage Regulator (#5)-is this the same as Alternator Regulator?

I will try disconnecting the wiring harness from the motor--and I'm guessing if the fuse still blows, I'll need to replace the wiring harness, otherwise I should be looking anywhere between the engine and the speedometer cluster, is this a correct assumption?

Thanks again for your help!"

"right you are, should have lo

"right you are, should have looked down. Here's what I'm thinking, the most common problem is with the accesories. Volt reg = alt reg. If you un-plug the harness to the engine it should isolate power to only the engine when you hook the battery up. The fuse will have power and the harnesss in the engine will be live. If the fuse doesn't blow then the engine is good, and the problem is in the wiring of the boat or gauges. If someone has hooked up the battery backwards then the rectifier would be shot along with lots of other stuff, be carefull."

"JB - I think I did in fact re

"JB - I think I did in fact reversed the battery cables the first time I hocked it up (they're both black), I have since traced and labeled the +/- and added the color coded covers, but do think i fried the rectifier and have not had any luck locating it... the fact that the diagram shows a dotted line after the rectifier usually indicates the location, but it does not appear to be there at least not the same shape/size, it is possible the previous owner used an after-market rectifier, but I'm not quite sure what/where I need to be looking for. Do you think If I took some photos of the engine it would help to post them here? I'll try the harness first when I get home from work and report back with my findings."

"Paul, this should help (n

"Paul, this should help (number 23 in the picture) - and besides, JB loves my diagrams

"

"JB- per your suggestion, I di

"JB- per your suggestion, I disconnected the wiring harness and the fuse stopped blowing, YAY! After tracing the wire from the engine all the way down to the cluster, I believe I found the faulty place... somewhere near the gas tank it appears the large wiring harness has been spliced or repaired earlier and the casing seems to be melted and brittle, it would make sense that the wires would melt together at this location as it's a weak link. It was getting to dark to really tell what was what--so I left it for another day.

As for the rectifier -- Grahm, thanks for the diagram... Yeah, I know the diagram shows the rectifier, and that's why I bought the part, but I can't seem to locate it on the engine it self. I've removed the ignition coil assembly identified by #21 and #26 in the diagram and all I see is the back of the ignition plate (#19)... is it behind it, or do I simply don't have one?

I guess I'll repair the fried wiring and see if the boat starts, and if not proceed to locating the the illusive rectifier... but judging from some of the responses I've been getting here and elsewhere it is often rectifier OR voltage regulator, but then again sometimes it has both... go figure.

-Paul"

"Graham a little slow today, t

"Graham a little slow today, to much corn whiskey, he didn't see the links above, ha ha. Don't worry about the rectifier it doesn't sound like its the problem with the fuse, although it might be a problem later. Repair the wires and get back to us."

"Hey, I heard that [img][/img]

"Hey, I heard that

Paul, the rectifier should be plain as day with that cover off. Making me suspect that it was toasted somewhere along the line and whoever had the motor didn't want to spend the 40 bucks at Merc (or 25 bucks aftermarket) to replace it.

Is there a couple of yellow wires just kinda hangin' there that go nowhere???"

"Thanks guys, Graham I'll

"Thanks guys, Graham I'll check for the yellow wires-- from memory I don't recall seeing any just hanging out. So it's not a vital part since they left it out or it is and they just sold the boat to me w/o it? I'll try to take some pics tonight to make this post a little more interesting

Thanks!"

That fuse has nothing to do wi

That fuse has nothing to do with the rectifier.
#5 on the picture is the regulator/rectifier. #23 is a terminal block only. That spot is where the cube rectifier used to be on the Gen 1 engine that had a 9 amp stator if it was upgraded. Merc stopped putting that on the 90 long ago. You cannot have both

"Hey Bandit--you are correct,

"Hey Bandit--you are correct, I do have a terminal block in the spot where the rectifier is suppose to be. Thanks it was driving me nuts that the manual shows it but I don't have one.

Well, I took the casing off from the suspected wire and the fears were realized and it appears worse then I imagined, the ground wire's casing is completely melted all the way down to the cluster. Bad, right? So what's the normal practice in situations like this? Replace all the wiring... if that's the case where does one go to get this long wire... cause RadioShack definitely doesn't have it. ;-)"

"<[img]"http://www.marineengin

"
The ground wire in the 12 wire cable? And popping fuses? That whole harness needs to be replaced. ~$250 US at the Merc dealer.
Here's what I think happened:
The black ground 16 gauge wire was trying to ground the the whole boat and got heated to oblivion. That fuses all the wires in the case together and causes shorts everywhere. The accessory lights and pumps need to have there own power and ground on the fuse box. Any wires behind the dash that connect the two together is a recipe for disaster. Especially any ground wire running between the gauges ground and the fuse box grounding point. If the accessory ground was failing back by the batteries than the load got transfered to engine cable and burned it out. Same with the positive that will pop fuses.
Looks like you have some major rewiring to do. Good luck..."

"'Bandit--You mean the har

"'Bandit--You mean the harness from the engine all the way down to the cluster? I could not find a part number anywhere in the online catalog... if this a generic part or engine specific? Any idea what the part number would be or you'd think they would know which one I need.

For your viewing pleasure:
The wire"">
Closeup"">
Burned to a crisp"">
The other end

"That is pretty well destroyed

"That is pretty well destroyed!!

side mount box:
84-17179a1 15 feet
84-17179a1 20 feet
Dash mount key:
84-816626A15 or 20 or 25. Depending on the length."

"<[img]"http://www.marineengin

" my own fault... live and learn.

Thanks for those part numbers, I've ordered one... I was hoping to the take the boat on our camping trip next weekend... don't know if that's going to happen."

Not entirely. The regulator is

Not entirely. The regulator is from flipping the connections. Check out what I said.

"A quick update and another wi

"A quick update and another wiring question... so last week finally I received the new harness and was able to get the boat started - YAY! Thank you everyone for helping me with this. As a result I pulled out a lot of old wire and it appears the boat manufacturer or perhaps the previous owner did not use the Mercury engine harness, instead it was cut off and a different plug was attached. I was able to figure everything out except for the 5-wire tachometer plug. I had to cut it since I don't have the female end of it anywhere and found the wires needed for the tachometer, battery, ground and the actual tack wire--the guage works, however I still have two wires I don't know what to do with, one is beige/blue that comes out of warning horn and another is brown/white and I have no idea what it is. I don't really know where to connect both of those or whether I even need to connect at all, the alarm horn does not sound the initial 2 beeps as it used to when you start the boat so I'd like to have that working if I can.

Thanks again for your help."

Just ignore those other two wi

Just ignore those other two wires. One went to a trim gauge the other to the horn. That beeper hock to a module on the engine that may be bad.

"Thanks 'Bandit!

It suc

"Thanks 'Bandit!

It sucked missing some of the best weather we've ever had here in Seattle, but I sure learned a lot about my boat. Thank you everyone for your help, I don't think I'd be where I'm at, if it wasn't for you."