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Johnson 130hp tach/Charge fault

F

FendtLad

New member
Hi All,

I am new to this site so appoligize if I am in the wrong section.

My issue is we brought a Johnson 130hp 4v outboard and the tacho flicks on and off while driving. Also while out using it I saw the charge indicator was below 12v when should be around 13.8ish.

I put the battery charger on to top up the batteries and seemed to charge but tacho is still playing up.

I cant seem to find any information on what wires to check coming out of the rectifier and what readings should be there to determine if the rectifier is faulty. All rectifier testings that I have googled are for different models and have different wire colours. My engine details are:

Model: AJ130TXERR
Serial: G03559524
Year: 1994

I seem to think the rectifer is at fault but would like to know 100% before buying a new one. Any help would be much appreciated.

Thanks
 
Everything points to the regulator/rectifier when the tachometer& charging system goes awry. MY resources do not go as far as some others on this site like joe reeves and racerone,they may respond later this morning.
 
johnnygjr said:
Everything points to the regulator/rectifier when the tachometer& charging system goes awry. MY resources do not go as far as some others on this site like joe reeves and racerone,they may respond later this morning.
Click to expand...

Thank you johnnygjr, thanks for looking, hopefully they might have something for me.
 
Your explanation indicates a faulty charging component as follows:

(Testing Tachometer With Water Cooled Regulator/Rectifier)
(J. Reeves)

A quick check is to simply plug in a another new tachometer as a piece of test equipment. If the new tach works properly and the old tach didn't, obviously the old tach is faulty.... but usually boaters don't carry around a spare tach (see below).

A faulty rectifier wouldn't damage the tachometer, the tachometer simply wouldn't work. This is due to the fact that the tachometer operates off of the charging system and the rectifier converts AC voltage to DC voltage, enabling the charging system. A faulty rectifier disables the charging system, and the tachometer simply doesn't register.

However.... those water cooled regulator/rectifiers that are used on the 35 ampere charging systems (and some others) bring into play a different type problem, and as you've probably found out, they are really a pain to troubleshoot via the proper procedure. There's an easier way.

The tachometer sending/receiving setup operates off of the gray wire at the tachometer. That same gray wire exists at the engine wiring harness which is connected to the engine electrical terminal strip. You'll see that there is a gray wire leading from the regulator/rectifier to that terminal strip, and that there is another gray wire attached to it. That other gray wire is the wire leading to the tachometer which is the one you're looking for.

NOTE: For the later models that DO NOT incorporate a wiring terminal strip, splicing into the "Yellow Wire" mentioned will be necessary.


Normally the Gray wire leading from the tachometer is attached at the terminal strip to another Gray wire which leads from the water cooled voltage regulator/rectifier...... remove the gray wire that leads to the tachometer. Now, find the two (2) yellow wires leading from the stator to that terminal strip. Hopefully one of them is either yellow/gray or is connected to a yellow/gray wire at the terminal strip. If so, connect the gray wire you removed previously to that yellow/gray terminal. Start the engine and check the tachometers operation, and if the tachometer operates as it should, then the regulator/rectifier is faulty and will require replacing. If the tachometer is still faulty, replace the tachometer.

If neither of the yellow wires from the stator is yellow/gray, and neither is attached to a yellow/gray wire, then attach that gray tachometer wire to either yellow stator wire, then the other yellow wire, checking the tachometer operation on both connections.

I've found this method to be a quick and efficient way of finding out which component is faulty.... the tachometer or the regulator/rectifier. It sounds drawn out but really only takes a very short time to run through. If the water cooled regulator/rectifier proves to be faulty, don't put off replacing it as they have been known to catch on fire with disastrous consequences.
 
joereeves said:
Your explanation indicates a faulty charging component as follows:

(Testing Tachometer With Water Cooled Regulator/Rectifier)
(J. Reeves)

A quick check is to simply plug in a another new tachometer as a piece of test equipment. If the new tach works properly and the old tach didn't, obviously the old tach is faulty.... but usually boaters don't carry around a spare tach (see below).

A faulty rectifier wouldn't damage the tachometer, the tachometer simply wouldn't work. This is due to the fact that the tachometer operates off of the charging system and the rectifier converts AC voltage to DC voltage, enabling the charging system. A faulty rectifier disables the charging system, and the tachometer simply doesn't register.

However.... those water cooled regulator/rectifiers that are used on the 35 ampere charging systems (and some others) bring into play a different type problem, and as you've probably found out, they are really a pain to troubleshoot via the proper procedure. There's an easier way.

The tachometer sending/receiving setup operates off of the gray wire at the tachometer. That same gray wire exists at the engine wiring harness which is connected to the engine electrical terminal strip. You'll see that there is a gray wire leading from the regulator/rectifier to that terminal strip, and that there is another gray wire attached to it. That other gray wire is the wire leading to the tachometer which is the one you're looking for.

NOTE: For the later models that DO NOT incorporate a wiring terminal strip, splicing into the "Yellow Wire" mentioned will be necessary.


Normally the Gray wire leading from the tachometer is attached at the terminal strip to another Gray wire which leads from the water cooled voltage regulator/rectifier...... remove the gray wire that leads to the tachometer. Now, find the two (2) yellow wires leading from the stator to that terminal strip. Hopefully one of them is either yellow/gray or is connected to a yellow/gray wire at the terminal strip. If so, connect the gray wire you removed previously to that yellow/gray terminal. Start the engine and check the tachometers operation, and if the tachometer operates as it should, then the regulator/rectifier is faulty and will require replacing. If the tachometer is still faulty, replace the tachometer.

If neither of the yellow wires from the stator is yellow/gray, and neither is attached to a yellow/gray wire, then attach that gray tachometer wire to either yellow stator wire, then the other yellow wire, checking the tachometer operation on both connections.

I've found this method to be a quick and efficient way of finding out which component is faulty.... the tachometer or the regulator/rectifier. It sounds drawn out but really only takes a very short time to run through. If the water cooled regulator/rectifier proves to be faulty, don't put off replacing it as they have been known to catch on fire with disastrous consequences.
Click to expand...

Hi Joereeves,

Thank you for your help and information, Regarding the tacho when I say flicking I mean it will be working fine then all of a sudden stop working for a couple of seconds then fire back up and may go fine for an hour or so then stop working for 10mins. Very intermittent. I will try the tests but can pretty much be certain it will be working fine when I strike it up.

Thanks again for your help. Much appreciated.
 
FendtLad said:
Hi Joereeves,

1 - Regarding the tacho when I say flicking I mean it will be working fine then all of a sudden stop working for a couple of seconds then fire back up and may go fine for an hour or so then stop working for 10mins. Very intermittent.

2 - I will try the tests but can pretty much be certain it will be working fine when I strike it up.
Click to expand...

1 - Yes I knew exactly what you meant. I've encountered just that many times since the alternator system came into existence in the early 1960's.

2 - The system being intermittent, I feel sure that when you first test it via the method I devised, it'll be in perfect operating condition... never fails. Leave the tachometer wires in the alternative mode as I stated for an outing. If the tachometer functions perfectly with no flicking, jumping around, dropping to zero, whatever... BUT returns to being problematic when you return the tachometer wiring to its rightful terminal attachments... that obviously proves my point.
 
We have just replaced the water pump and rectifier. The water pump definitely needed replacing due to the last cowboy mechanic put to much sealant around outside of impeller casing which blocked the bleed port up. Question: When engine is running at idle should there be 13.8v charging? We only have 12.4v and it doesn't change much when you increase the revs. We have yet to try it in the water to give a decent test. Could there be a stator issue not supplying current? is there a test for that?

Thanks
 
13.8 to 14.7 would be good at 2000 rpms. The stator assembly has charge coils that charge the batteries. there is a test for that with a dvm
 
johnnygjr said:
13.8 to 14.7 would be good at 2000 rpms. The stator assembly has charge coils that charge the batteries. there is a test for that with a dvm
Click to expand...

Also the new rectifier has 2 yellow wires both without trace colours on them. It doesn't matter which yellow colour they go onto leading to the stator? Am I correct in my thinking?
 
I have charged the batteries overnight. Started and tested voltage and now have 14.3 volts at idle. Any ideas why it wasn't charging prior to charging the batteries? Or could it be that since the rectifier is only a 10 amp one it takes a while to come up to 14v?
 
If this makes sense, the alternator needs 12 volts from positive battery post to positive battery terminal on the alternator, Usually the single red wire to the back of alternator, You need 12 volts to make14.3
 
johnnygjr said:
If this makes sense, the alternator needs 12 volts from positive battery post to positive battery terminal on the alternator, Usually the single red wire to the back of alternator, You need 12 volts to make14.3
Click to expand...

Thanks for that johnny, I hope to get it in the water soon so will give it a good test then.

Thanks everyone for your help thus far. Will let you know how I get on.
 
Apologizes for taking so long to reply. We have had the boat in the water this weekend and seems to be charging fine now so problem solved. Thanks everyone for there input. much appreciated. I need to start a new thread now regarding the steering on it. Thanks
 
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