Tach not working at Idle but works above 1200 RPMs

[Bergertime]

This one puzzles me...

Just recently my tach (all other guages work fine) has stopped working at idle speed.  When I increase the throttle above approx 1200 rpm whether on the hose or in the water the tach jumps to life and seems to be correctly reading engine RPM. At cruising speed my GPS speed matches what I have been normally getting at 4200 rpm so I feel the reading is accurate there.  When I back off the throttle and the engine slows to idle (idling fine now) the tack drops to 0.   Do you all have any suggestions as I am hoping this is a simple issue..

One other electrical question, may or maynot be related: Before I charged my batteries (both were very drained) my volt meter on my dash would read approx. 13.5v to 13.8v give or take a little when operating at cruise speed.  After the first complete charge and I have performed a subsequent one as well my volt meter on the dash rides just above 12v with my GPS saying 12.3v being supplied when at cruise.  

Question: Does this meter fluctuate based on demand? Meaning, since I charged both batteries (110 AC Smart Charger) that the charging demand on the motor is less or should it read the 13v+ all the time regardless of the charging state of your batteries.  Hope I can get some insight on both.

Thanks,

B

[fitz73222]

Well there is typically a correlation between tachometer function and charging system function since the tach gets its signal from the charge pulses. I like to see 13.2-14.2V at cruise. If your cruising at 12.3V you have a problem that may be causing your tach issue.

[Bergertime]

Thats what I am affraid of..  Where would you start?

B

[Capt. Bob]

One other electrical question, may or maynot be related: Before I charged my batteries (both were very drained) my volt meter on my dash would read approx. 13.5v to 13.8v give or take a little when operating at cruise speed.  After the first complete charge and I have performed a subsequent one as well my volt meter on the dash rides just above 12v with my GPS saying 12.3v being supplied when at cruise.

If the battery is fully charged and you have just normal draws on the system (think GPS/VHF/Sounder) you should be reading the output of your charging system minus this draw. I would bet your charging system (when functioning correctly) resides between 14.2-14.6 volts +/-. That's a guess based on my 91 Yamaha which is the same. This voltage output is designed to occur at 3500 rpm as per Yamaha but can go as high as 15 volts +/-. This is based on the charging components age/condition and original specs. In other words, they have given themselves a lot of wiggle room.  

Question: Does this meter fluctuate based on demand? Meaning, since I charged both batteries (110 AC Smart Charger) that the charging demand on the motor is less or should it read the 13v+ all the time regardless of the charging state of your batteries.  Hope I can get some insight on both.

Yes it does but.....
First, if your battery was not fully charged, the voltage indicated would be lower at the start and get higher as the percent charge increased. Let's assume your battery indicated 12v on the meter when you turned on the key but dropped to 10.5 when cranking. Motor fires, you move off and proceed to cruise speed. Your voltage indicated will not be in the high 13s or low 14s at this time. You might be reading in the high 11s or low 12s  but it should slowly increase as the battery demand for charge is reduced over time. This is why, as Fritz states, you want to look for that sweet spot on your charging system as he has indicated. This tells you that the system is functioning as designed, your battery is living in a full state of charge and your other electrical systems are being supplied with correct voltage without taxing the motor charging system.

The tach, again as stated is a good indicator of the charging system condition. I would also asked if you feel that your batteries are indeed fully charged and are in good condition.

Most problems I've read about seem to finger the voltage regulator in your system when the tach starts to act funny. Still, my first look would be the battery(s). Using mine as an example, when they are fully charged (using a smart charger), my voltage indicated is around 13.2 volts (to be clear, this is what I'm seeing on my volt meter when I turn on the key before starting). After starting (I'm at home, running on muffs) with the tach indicating 700 rpm, my voltage meter will read in the mid 13s and climb as high as 14.9v during this flushing process.



 There are no additional loads on the system of course but that is a good indicator of the motor charging system at work. The regulator somehow "dumps" excess voltage to keep from over charging but these older systems are not as sophisticated as newer ones on cars and some outboards.
This is the reason (the wide spec spread) that Yamaha Engineers (Japan) still recommend using only flooded batteries with their outboards. CYA baby. Still many Yammy owners use (myself included) AGM style batteries. Truth is, I also have a Gel.

Good luck.

[Bergertime]

If my issue is the regulator / rectifier how hard is it to replace in the driveway?  Is this something I would want a mechanic to do or a do-it yourself type of job?  I looked up the part and looks like its kinda burried from the schematics on Marine Engine . com.  Not wanting to bite off more than I can chew or run the risk of screwing something else up.

B

[Capt. Bob]

The regulator on the Yamaha is fairly accessible. I need to do some searchin'. I apologize if I gave you the wrong possible culprit.

Here's a start:
viewtopic.php?p=103716#p103716

[Bergertime]

This may help:

http://www.marineengine.com/parts/johns ... ion+System

Item# 57

B

[Capt. Bob]

Look at the link in my last post. It will get you started on troubleshooting the problem. There is also another link a few posts down that takes you to a CDI site you can navigate through to increase your understanding of the entire ignition/charging system.

On the Yammy, the CDI cover(?) comes off and the regulator is very accessible. Might be the same for your Jonnyrude.
Price...

Good luck.

[Bergertime]

Thanks!  I just got done looking at the link provided and it was very informative on troubleshooting.  Much appreciated Bob!  Just another bump in the road!

B

[Georgie]

B-

The symptoms you mention do point directly towards the rectifier/regulator, but I'm not a fan of buying replacement parts without confirming diagnosis, especially since you generally can't return electrical parts.  I don't have a Looper service manual to verify specs, but if you can find someone who does (Beuller???...Beuller???....) and you have a decent voltmeter you can test the function of your rectifier/regulator to verify if it's bad.  That said, worst case scenerio some of the fasteners/bolts might be buried under the flywheel (the later model crossflows were frustratingly buried  :evil:  making what used to be a 3 minute job take MUCH longer if the flywheel was stubborn).  Aside from that potential headache, the rest of the replacement job would be something you tackle without much difficulty.  I can verify on my neighbor's 225 tonight if it helps.

[Bergertime]

Ryan,

Several other people have said the same thing especially since the faulty reading on the tach is accompanied with low voltage output per my gauge.  I have looked at the diagram but can you give me some help on where it's located on the motor.  That with the diagram I should be able to determine if it's something I want to tackle.  As far as diagnosis goes I was just going to buy (then return) a standalone tach and plug it in to see if the problem (reading zero at idle) is present. My thought was that if I could rule out a faulty tach then the next stop was the rectifier.  Unhooking and hooking up pairs of wires makes me a little uneasy which was suggested in an older thread. If it’s not a big deal verification with your neighbor would be greatly appreciated.  Thanks

Bruce

[Georgie]

B-

Based on the schematic, the regulator/rectifier is located directly underneath the powerpack (Part #57) at the aft top of the powerhead.  If you can get to the bolts identified by #45 on the schematic, then you should be able to do the replacement without taking off the flywheel.     Just color code or label the wires/plugs and take photos from every possible angle before you start disassembling things and continue to take more photos as you go. This is definitely a very managable DIY project.

...and not to insult you or restate the obvious, but make sure your battery connections are all clean and tight.  Poor/intermittent ground connections cause a myriad of electrical issues.

[Bergertime]

Thanks again Ryan.. your guidance is much appreciated!

Bruce

[bondobill]

I had the same issue on my 200 Yami a couple years back.
Wasn't charging.
Batteries where around 6 years old so I thought maybe they where the problem, I replaced both of them at a cost of over
$300. Didn't help, still not charging over 12 v.
Me and electrical issues don't get along so I made a appointment to bring boat to a shop on the following Monday.
I had a service manual for engine so on the Sunday morn before I was to bring the boat in I thought what the heck I'll read through the electrical trouble shooting section. Manual said the majority of charging problems stem from either a loose or corroded connection or a bad wire.
well I popped the hood and started tightening every bolt and nut on the electrical system.
When I got to the regulator it had a ground wire running to metal bracket it was mounted to, when I tried to tighten the bolt it was tight but I could move the wire around on the bolt   . Turned out the mechanic I had bought the motor from the year before had installed a bolt that was too long and was bottoming out before it made good contact with the ground.
Why it took a year to create a problem I have no idea.
Installed a shorter bolt and fired her up and she was charging again.
You might get lucky like I did and have nothing more than a loose wire somewhere.
BTW
the batteries I thought where bad   while one is in my Vette ,and the other is used as a jumping battery  

Bill

[Bergertime]

All -

Well, after I got back from using the boat last week I was trying to trouble shoot an intermittent trim/tilt issue I have been dealing with over quite some time before digging into the testing of my regulator /rectifier. This time re-seating the relays had no effect (I know I am getting power there) so I started to dig into the wiring under the relay mount and found nothing wrong.  I decided to change out the relays and replaced both with new ones and now it works perfectly.  

However, (here comes the bad news) as I was working in that area I notice a large chunk of magnet attached to the side of the starter...  Out came the four letter words knowing what that meant!!!  Well to keep a long story short (pics included) that piece of magnet is not supposed to be there and was certainly missing from the flywheel (pics included).  

Pulling the flywheel was more than I wanted to take on myself so I took her into a trusted mechanic.  Well, I had three magnets that needed to be replaced and my stator was totally hosed causing my voltage issue and likely a host of other problems.  When the magnet came off it severely damaged every single one of the coils so I am not sure how my engine was even running or generating any voltage.

Got her back last night and took her out for a run... She runs like new, tach working and the voltage output is in the correct range at idle and cruise!  Was not an inexpensive repair but a necessary one.  Thanks again to all.. Hope this thread may help some newbie like me in the future.





Calm Waters and Tight Lines.
 

B