1993 Johnson 90 electrical problem...Help!

[piniongear]

I started my 1993 J90 for the first time after a piston replacement. Started easy, ran well. Kept the engine rpm at 3500 or less thru out the day.<br />All day the volt meter showed 13v charging rate. I had put a new CMC power lift jack on the boat at the same time I replaced the engine. Out in the bay the lift stopped going to the low position. It would only raise. After going up all the way, it would not come down so I decided to head back in.<br /> The engine ran fine, except I had to reduce speed due to the elevated engine position. I suddenly noticed the volt meter read 18v rate (pegged the needle on high side) and I looked at my tach to note rpm. The tach was sooty black inside the glass, looking like it had burned and of course was not working. Did the overcharge rate blow the tach?<br /> I pulled the boat out and went to the wash rack to flush the engine. Ran the gas out while the engine idled at normal speed and the volt meter now read 13v. After gas ran out I pulled the engine cover and touched the flywheel.<br /> I recoiled from the flywheel heat! It was so hot that I could not hold my hand on it without getting burned. At the same time I could lay my hand directly on the engine block. While it was quite warm, it was nothing close to the heat on that flywheel.<br /> Anyone have any ideas? That J90 has a 9amp charging system. The tachometer is (was) an OMC 6K unit that I had on the boat and used with my 1978 140HP Evinrude that preceeded this newer 90HP engine. I connected the tach up exactly as my 140 had been connected.<br /> My main question regards the high charging rate and secondary concern is the failure of the brand new power lift.

 

[Silvertip]

Re: 1993 Johnson 90 electrical problem...Help!

Check the voltage at the jack plate motor while someone puts the switch in the down position. No voltage at the motor indicates a wiring/switch problem. If there is voltage at the motor, there is a motor problem. If the motor actually runs, its a hydraulic problem assuming this is a hydraulic unit.<br /><br />As for the tach/electrical problem, the reglator may have blown and quite possibly due to the jack plate problem. This is even more possible if you didn't install fuses in this system. A shorted motor would place high load on the electrical system possibly frying the regulator and in the process, your tach. The volt meter at idle would probably still read 13V even though the regulator is bad. High voltage is also responsible for the tach failure. I think you need to carefully check the jack plate wiring and any other wiring in the vicinity. Pulling the flywheel is also a good idea to check the physical condition of the electrics under it. Sounds like things really got hot. Fix the jack plate first.

 

[piniongear]

Re: 1993 Johnson 90 electrical problem...Help!

Thank you for the suggustions. I agree with what you say because the dealer who I bought the boat from has a good rep and is trying to help me, and I think he sold me an engine without problems.<br /> I suspect the CMC lift resulted in the other problems. I used fuses, but find none blown. I had pushed the reset button the first time the lift failed to lower and that made it work. However, it quit again and then would only go up after that.<br /> The boat is sixty miles away from home so I plan to go down tomorrow and look at the CMC lift first. It is a hydraulic unit but I agree, it is most likely something electrical.<br /> I will let you know what happens, and thanks again for the help.

 

[Silvertip]

Re: 1993 Johnson 90 electrical problem...Help!

OK - if you pressed a reset button, that means there is a resettable circuit breaker in the system. It is apparently in the main 12V line feeding the system and this is where it should be. If that CB opens, the motor is drawing too much current or there is a nasty short in the system. Make sure the jack plate is not binding as it tries to raise or lower. Keep posting things you find and we'll get this thing working.

 

[piniongear]

Re: 1993 Johnson 90 electrical problem...Help!

Thanks Upinsmoke! It turned out to be too cold for me to head down there yet, but I will soon.<br />Pushing the circuit breaker reset button only worked the first time I pushed it. After that it did not.<br />Let me get your opinion on this:<br /> The lift motor wires look to be a size 10ga. They were 6 feet long and connect to the relays with a plug, and then there is perhaps another 1 ft. of wire to relays. Because I needed a dry place to mount relays, I had to add 12 ft of wire up to the console. I used #10 for this so that it would match the original size. I do not know what the motor draws (a large load I would think) but the two relays are 40AMP. That seems heavy for a 12V system.<br /> I may have gotten some kind of short, which in turn blew the engine's rectifier (voltage regulator?) and that of course blew the tach and heated up the flywheel. I am going to closely inspect the engine wiring for heat damage.<br /> I will keep you up to date. Thanks again....Perry

 

[ob15]

Re: 1993 Johnson 90 electrical problem...Help!

After reading your post again piniongear you siad you run the gas out of the motor. I'm not sure if it was missed but you will find that most of the experts here (and please don't consider me one)do not reccomend this. When you run out of gas you run out of oil also. Don't want to kill the motor from lack of oil. Just thought I'd let you know. Hope you get your problems figured out.

 

[Silvertip]

Re: 1993 Johnson 90 electrical problem...Help!

40 Amps is a heavy current draw but think of the lift motor like a trolling motor. They are typically fused/breakered with 40 or 50 Amp devices. Without a circuit diagram for this installation it will be a challenge to troubleshoot but there are two main circuits to consider. First, the main current feed to this system should be from heavy gauge (probably 10 ga.) red and black wires that likely connect directly to the battery. They should not be tapped into any smaller gauge wires. Then there is the control switch circuit. The switch (up/down) activates the relays to provide the up or down function which amounts to low current used to control a large current. These should be smaller ga. 12v and gnd wires feeding that system as well. The +12V wire to that system could be switched or hot depending on whether you want the system to function only with the ignition on or not. It appears you have a catastrophic electrical problem so you need to look into the lift system wiring before going after the engine or you may just ruin the engine repair. Keep us posted.

 

[piniongear]

Re: 1993 Johnson 90 electrical problem...Help!

Looking under the floor I found the motor wires (two) had come unplugged from the harness due to a very poor design of that plug. I plugged it back together and wrapped it with tape. The lift now works fine in both directions.<br /> I found no sign of wiring overheating under the flywheel or around the rectifier. I still do not know why the engine was overcharging at 18V, nor has my dealer have any idea what it may be.<br /> He loaned me a shop tach to try the next time I get down to the boat. I did not want to buy a new one and then blow a hole in it as happened to my old tach. I pulled the old tach off and the case was melted and a nickle size hole was in the side of it.<br /> So, other than the charging problem and the ruined tach, I am getting closer. Thanks again for the help on this.

 

[Silvertip]

Re: 1993 Johnson 90 electrical problem...Help!

Glad you found the problem and it turned out to be a simple fix. If your voltmeter is reading normally (13.5 to 14.6 or 15 max) between 2000 RPM and wide open throttle, your regulator was not damaged. If it still reads near 18 volts you need a new regulator.

 

[piniongear]

Re: 1993 Johnson 90 electrical problem...Help!

Yessir Upinsmoke, that is the next thing I will check. The last time out it read between 13.5 to 14.6v until the lift quit working. Then it shot up to 18V and blew the tach. At the wash station on the trailer it was back to reading 13.5, but of course the engine rpm was only 1200 max.<br /> So, you are saying that I will know if the rectifier is gone if it overcharges above 2000rpm?<br /> That certainly makes sense. I may have damaged it. I will let you know. Thanks again for hanging with me on this problem. You are a great help!

 

[Silvertip]

Re: 1993 Johnson 90 electrical problem...Help!

Actually, the rectifier is part of the regulator and not a separate unit. If the charging voltage is too high, the regulator will need replacement. Hopefully you won't have to change it but the fact that the tach was smoked, the electrics have been taken a hit.

 

[piniongear]

Re: 1993 Johnson 90 electrical problem...Help!

Upinsmoke, I ran the boat yesterday and this is what happened: The first hour the volt meter read 14V plus a tad. Nothing less, nothing more. All of a sudden the volt meter needle creeps up to a good 16V. After a minute or so it goes back down to 14+ again. I ran the boat for a good five houra and it never got to 18V as it had before when it blew out that old tach, but once it was at 17V.<br /> The loaner tach did not blow, and I returned it to the dealer today and discussed the situation. He nor his mechanic can be sure what is going on. I guess I will just keep running it and see what happens. <br />Thanks again for your help..........piniongear

 

[Silvertip]

Re: 1993 Johnson 90 electrical problem...Help!

I wonder if you don't have a sticky volt meter. These are not especially precise either. Buy or borrow a volt-ohm-milliamp meter and next time out, connect it directly to the battery and monitor it during your outing. On long runs 16, 17 and 18 volts can overcharge a battery. The other problem is that most electronics (radios, locators, etc.) can't safely handle anything more than 15.5 volts. On your last outing, the behavior would be normal since the battery was relatively low and was taking a significant charge which would load the alternator. As the battery charged, it unloaded the alternator so the voltage began to creep up. I still feel you have a regulator that is marginal at best. If you have a shop manual, the meter I recommended can be used to test it.

 

[piniongear]

Re: 1993 Johnson 90 electrical problem...Help!

Thanks Upinsmoke. I agree with you about the regulator being highly suspect. I always keep my battery at home with a Battery Tender hooked to it 24/7. In addition to that, the battery is an Optimal that is not possible to add water to. You could mount this battery upside down. My dealer thought water would be boiling out if the alternator was overcharging, but when I told him what battery I was using he ditched that thought.<br /> I now have a new tach on the boat and I am going to run two wires (temporary only) off that volt meter so that I can quickly attach a digital multimeter to it when the charge rate goes up to double check the volt meter, as you suggest.<br /> I ran this volt meter with my old engine since 1978 and never had a problem until I put the 1993 engine on the boat. That makes me think I have regulator problems. Will stay in touch.......PG