1989 Evinrude 150SL Tach Trouble

[madbanchee]

I just bought the boat a couple of weeks ago... It had an inoperable fuel guage and tachometer but i thought "I can fix that!" So here I am, the fuel sender floats were saturated, now fixed. The tach however has me stumpped. The first time on the water I noticed the volt guage rise near 18v on WOT so I started looking into the regulator/rectifier module, found the gray tach wire on the terminal strip of the engine, measured it with a DVM and had nothing. So I started shopping the web and found this link... <br /><br /> http://outboardparts.com/omc/mall/electronics/140150rect.htm <br /><br />If you look at the "details" for the part (193-5204) there is a note that says this...<br /><br />"Warning!! Walmart and AutoZone marine batteries are incompatible with this regulator. The Duralast and Everstart batteries are overcharging and even a new regulator will fail. New circuits are being experimented with."<br /><br />Well, you guessed it, I have an Everstart battery in my boat! I called the vendor (outboardparts.com) today and asked what these findings were based on. I was told "The manufacture, CDI." and nothing further. Yep, I called CDI Electronics and they confirmed this and told me that this is common knowledge in the industry and that it's typical for the DIY'er to not get word of this unless he was an avid boater who went to trade shows and read the trade magazines. CDI also told me that this was a common problem with the OMC/Evinrude parts however the OEM parts would probably last a little longer. BTW, the local dealer I called before I called CDI said they never heard of this and would guarentee the part for 90 days. Anyway, CDI told me if I replaced my battery with an Interstate or something else there would be a good chance my problem would go away and the tach would work.<br /><br />So here I am, I did swap the battery with an Interstate I happened to have. Now, the gray (tach) wire on the terminal strip and infact the back of the tach itself now have about 7.5-8 volts DC (at idle) but the tach still does not work. I bought another tach from a liquidator for $30 but that doesn't work either. The tach I bought looked like it had been kicked around without the box so I really can't say it was new. Could it be possible that I now have two bad tachometers? Without having a "peak" volt meter is there anything I can do to verify the tach signal I see is real? I did notice on the DVM the amplitude increased slightly as gave a little throttle to the engine (9.1v maybe). If I get my hands on an oscilloscope does anyone know what I can expect to see. Likewise, this stems another thought, can I drive signal into the tach from a function generator to test it?

 

[Joe Reeves]

Re: 1989 Evinrude 150SL Tach Trouble

The tachometer on that engine operates off of the charging system.<br /><br />The tach usually has four terminals:<br /><br />"S" (sensor) = Gray wire<br /><br />"G" (ground) = Black wire<br /><br />"I" (ignition) = Purple wire<br /><br />"L" (light) = Blue wire<br /><br />On the back of the tach is a numbered dial which should be set to #6.

 

[madbanchee]

Re: 1989 Evinrude 150SL Tach Trouble

Thanks, but I have all that already. Sorry for the long post but the real question is what is the signal supposed to look like? What should it read on a DVM? Likewise, can I simulate some way to verify the tach? Thanks again.

 

[madbanchee]

Re: 1989 Evinrude 150SL Tach Trouble

So I did this...<br />I fed a 525 Hz signal from a frequency generator in to the original tach as a bench test and it read 5250 RPM as expected. It calculates as follows...<br /><br />525/6=87.5 (use the factor of 6 for PUL/REV)<br />Since 87.5 represents the REV/SEC, multiply by 60.<br />87.5*60=5250 RPM.<br /><br />I figured this is a fair way to not only test the tachometer but also verify the accuracy. My tach happens to be within 50 RPM. I don't think I can expect anything closer than that for an OEM tach that's 15 years old!<br /><br />I wish I would have thought of this before I bought the replacement but heck, now I have a shop tach! I just have to justify this somehow with the wife!<br /><br />So, the realization is this... The regulator/rectifier module's tach output must be a straight DC voltage. I'm kind of thinking something as simple as a resistor of an RC filter is blown inside the module leaving the capacitor saturated. I might play around with a couple of R values on the back side of the tach but I probably should get the boat back on the water and see what the regulator's charge circuit is doing.<br /><br />Has anybody here ever heard of a reg/rec failing this way?

 

[kmaglothin]

Re: 1989 Evinrude 150SL Tach Trouble

Your post is a very familiar problem as I am going through the exact same issue. Johnson GT150 ...replaced rec/reg...overcharging just like yours...I had a Walmart battery (Everstart) so I replaced it with a Sears Diehard Marine battery and it made no difference at all. I am now in the process of sending the rec/reg back to CDI to check it. I am probably going to get told that it is fine and then be charged $25 dollars for them to check it. I am still wondering how the "cart can drive the horse" so to speak by having the battery "tell" the regulator what to put out. So I tested the sensing circuit and it sees the normal battery voltage so why then would the regulator put out 16 - 18 volts when the battery doesn't need it. I have isolated everything from the battery and still get the same readings. Talking about frustrating. I am VERY interested in what ever you find out.

 

[kmaglothin]

Re: 1989 Evinrude 150SL Tach Trouble

I just received this reply to my overcharging problem from CDI...I will need to see what they are talking about before trying this test but I thought I would share it with you...so for what it is worth here it is...<br /><br />"The purple wire is the sense wire if the voltage is lower on this wire then the system will overcharge. You can bypass the purple wire by hooking the purple wire out of the regulator directly to the red wire for testing. If it continues to overcharge then the regulator may be defective. send it in and we will test it and replace it if it is still within the years warranty.<br />Thansk<br />Ray"

 

[madbanchee]

Re: 1989 Evinrude 150SL Tach Trouble

Ranger, I will find out more this weekend when I get the boat back on the water (as long as the weather holds up, looks like rain in the forcast though). I will be able to get the RPM up to monitor the voltage and see if I'm still overcharging. I'm curious though... did CDI suggest anything if shorting the purple wire eliminates the overcharging? Think about it.<br /><br />Another thing, is your tach output doing the same as I described? I think I can get my hands on a scope and should be able to look at the signal on the tach wire. If you look at the install instructions for the regulator (CDI p/n 193-5204) the last note on the bottom of the page mentions checking the tach wire for 10K ohms to ground. This must be a pull-down of some sort like I mentioned earlier. I'll let you know what I find out tonight. BTW have you ever heard anything about air getting trapped in the top of the block and preventing the regulator to cool?

 

[kmaglothin]

Re: 1989 Evinrude 150SL Tach Trouble

No...at this point they have not told me what could be the alternative to a bad regulator. I thought I would eliminate the regulator first then go from there...I really believe the regulator is bad...because I have already tested the sensing wire (purple) and I know the reg/rec is seeing normal battery voltage but I will try their test.<br /><br />My tach is stable...although when I first installed the new reg/rec it was erratic but I think that may have been a bad connection that I resolved.<br /><br />As far as the heat buildup...yes...at least on my model motor there is a problem with heat buildup at that area of the motor. I have been told this by two different techs. It also plays havoc with the stator after a few years of running...I had to replace my stator due to the heat damage to the charging coils that are located directly above the reg/rec...the coils had started melting and there was obvious heat damage to the coil cases. <br /><br />I will let you know what I find out...I will test it later this afternoon.

 

[madbanchee]

Re: 1989 Evinrude 150SL Tach Trouble

I've heard of a way to vent the top of the block by drilling and tapping a hole above one of the the top cylinders at some specific location and then moving the water "pee" hose from the side of the block to this new location. It sounds a little scarry to do this without doing a full tear down on the engine and risking metal chips/shavings getting inside the block. Afterall, I can't say I ever saw a magnet that picked up aluminum. The note I read on this said to use thick axle grease or something to retain the chips as the hole is drilled and tapped. This may 'help' the situation but I'd be afraid that's all it would do. I can understand how air might get sucked up on a tight turn with too much trim but I guess one must be careful how they drive.

 

[kmaglothin]

Re: 1989 Evinrude 150SL Tach Trouble

From what I have been told the heat effect takes a while to occur. I have not read about the venting that you wrote about but as for me I would say the risks would outweigh the benefits of that modification. My reg/rec just went out over the last month...my engine is 17 years old and I am the original owner...so if I can get another 17 years out of this engine I could live with that for sure.

 

[kmaglothin]

Re: 1989 Evinrude 150SL Tach Trouble

Well...isolated the regulator...made no difference...it seems to be freeflowing...sending out whatever the stator sends it. So...I will box it up and send it back to CDI. Don't know if you have the same problem but I have heard from a number of people that these units are coming from CDI faulty.

 

[madbanchee]

Re: 1989 Evinrude 150SL Tach Trouble

Well I don't have anything to tell as far as overcharging goes but I did measure the tach signal with the scope and got a pretty clean dc line; hardly a ripple. The tach line also has the 10K like it is supposed to. Overcharging or not, I'm pretty convinced I need a new regulator. I'll post again after I get the boat in the water.

 

[kmaglothin]

Re: 1989 Evinrude 150SL Tach Trouble

I would say that if you are getting 18 volts when running you probably have a bad regulator. My problem was that I had just put on a new regulator and was getting overcharging...before that I had low voltage...in the 11 volt range all the time. One thing you can do is look at the top of the reg/rec module and look for any melting or cracking. After I got my old one off it had a bubble on it and had cracks throughout.

 

[holy ghost flies]

Re: 1989 Evinrude 150SL Tach Trouble

i had a simular problem with my 1991 150hp evinrude. it was the retifier. if the tach don't work that is a 75% chance of being the problem. the retifier converts the voltage from ac to dc and it runs the tach. it will run around 250 dollars for a 35 amp and for a low amp as cheap as 50 dollars

 

[madbanchee]

Re: 1989 Evinrude 150SL Tach Trouble

Well, CDI was mostly right... the battery no longer overcharges and maintains 13.5 to 14 volts. Who would have thought the battery itself would couse a problem! I still do not have a good tach signal. I have DC output from the regulator but no pulse. I guess the rectifier is bad and will need to be replaced. I did find the regulator module somewhere on the web for $160 shipping included. All the local dealers want $200 - $212.

 

[kmaglothin]

Re: 1989 Evinrude 150SL Tach Trouble

I have sent my reg/rec back to CDI for testing...I have changed batteries already and didn't see any change. I am eager to see what CDI finds out about the regulator section of the module. I guess I should prepare myself for them saying the module is fine and then need to look for another battery.