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My father-in-law's Gravely recently had its voltage regulator replaced without being tested (shade tree mechanic friend who was "sure" that was why the battery isn't charging.)

Today I downloaded from kohler.com a service manual (Kohler Courage 23 engine) and the parts manual for this machine from Ariens. I could not find a service manual.

The Kohler service manual does describe how to check both the regulator and the stator, running or not running. Seems that info came about $75 too late because that's what the local shop charged for the new regulator. The friend turning the wrenches didn't ask the man behind the counter to test the regulator and now the old one's gone.

Model 992143
early serial (000168)

So today we realized this mower has a second fuse. I pull the fuse and yep it's blown. Father-in-law says he'd never touched the fuse. It was a 20A so that's what I put back in. Tonight I confirmed from the Gravely wiring diagram that 20A is the correct size fuse. It's a purple wire coming off the regulator's B+ terminal.

Popped in the new fuse and now the battery shows another volt (about 13.4) when running. Yay, fixed. Ran it a little while, pulled fuse, fuse still good, hand the mower off to the wife and she runs it all over the yard and let me tell you that grass didn't stand a chance. Looking good. She stopped it once or twice during her session and it restarted.

Finished after about 40 minutes to park it and it would not start. Barely enough to bump the starter but not crank over. Check fuse ... its bad.

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Still with me? So I'm thinking:

1) Follow the purple wire everywhere possible and verify there's no exposed wire shorting to ground. But other than that, what would cause so much current to be in that wire?

2) The Kohler manual says there should be no more than 14.7v coming from the B+ terminal of the regulator. Again, we haven't actually tested that but instead did test at the battery, 13.4v when engine running (and fuse not blown).

3) Would a bad stator send a crapload of amperage out? I didn't read anything anywhere about testing for amperage from the stator nor regulator, just voltage (at least 28 VAC from stator according to Kohler.)

At the risk of complicating the issue before adequately checking what I know to check I've just now also read of some additional possibilities:

-- random freed bolt or conductive debris coming in contact with stator (pull flywheel to see)

-- weak fuse holder causing vibration-induced connection/disconnection of the fuse blades that causes an electrical spike (do all regulator/stator tests first)

-- PTO clutch gradually drains system as heat/time builds up (disconnect PTO clutch and engage PTO switch and see if fuse blows or doesn't) <<--- seems iffy, since the PTO isn't in that circuit and never stops working.


Tonight, sitting at the computer, I'm REALLY liking the weak fuse holder idea. This one does flop around, and yes the fuse does go in and out of the holder super-easy. I could slightly bend the fuse blades to get them to hold more securely, zip tie the fuse holder to something stable, and then see how long the fuse lasts.

I ran some tests according to the Kohler service manual.

The first test is to see if charging rate increases with RPM. It does, although I don't have a way to use their specific test load. And instead of using an ammeter at the rectifier/regulator's B+ terminal I watched the voltage reading at the battery increase when RPMs were increased beyond idle.

The second test is to remove the connector at the rectifier/regulator and measure AC voltage at the stator wires at normal engine running speed. I get 34.5 volts AC at about 1/4 throttle. (This mower lacks a strong park brake. I won't run it full throttle without sitting in the chair. It could launch itself through a wall. Anyway, it passed the test. (Test is for "at least 28" VAC at a higher RPM).

The third test is stator resistance. This was trickier because my meter's lowest range is 200 ohms and the test looks for a range between 0.064 ohm and 0.2 ohm. My digital meter does not resolve that finely. Touching the leads together reads about 0.05 or 0.06 ohm; at the stator it reads maybe 0.1 higher? I sorta forgot the exact number actually but doing the math it seemed in range.

The 4th test is to look for continuity at each stator wire to ground and there was none (test passed).

The 5th test is the lone test for the rectifier/regulator. It wants to see "no more than 14.7" VDC from the B+ terminal (not at the battery). I saw 14.9 at the lower RPM. Again this is for a supposedly new rectifier/regulator. That translated into about 14.0 volts at the battery.


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I made a mistake last night an inserted a 25A fuse. My father-in-law mowed part of his yard for a solid 30 minutes but the fuse didn't blow (or melt anything, but he did say the fuse holder was warm ...)

I've put a 20A back in and zip tied a few things I saw dangling. I'm going to mow a while and blow another fuse ... I suppose.

Update
(since there are so many here concerned with the outcome)


Mowed some. Fuse OK. Mowed more. Still OK. Aimed for the entire yards all around. Nothing heavy or tall, but lots of ground to cover over a lot of bumpy terrain.

Eventually I drained the left tank and discovered what seems like an issue with the right tank gas delivery. (Ran for a minute or two, mostly did not. I swapped gas caps in case the Right one's air vent was clogged but that didn't help.)

During all of these restart attempts while I was farting around with the tanks, I'd say the starter a couple times would not budge (like a dead battery?) but overall it cranked like normal. Do the Kohler's have a hot-start condition? Does the starter or solenoid or something get heat soaked? I finished what I wanted to mow on the Left tank.

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Speculation:
If there was any problem with a weak fuse holder I helped that by slightly bending the fuse blade to create a secure connection. As noted I also zip tied a couple things flopping around, But I never found anything frayed, exposed, etc.

Oh, and when I'd disconnected the rectifier/regulator to run the tests, its connector might not have been plugged in totally completely by the last guy. I just don't know for sure. When I reconnected it it seemed to not want to go on fully but I made a point of carefully squeezing the connector one as flush as I could get it. Maybe I got it on more completely.

I'm mostly convinced the stator and rectifier/regulator are OK unless someone here tells me otherwise. I'm done for the night but will check the battery in the morning and charging status again.

This morning the battery shows about 12.7v.

Starts right up. I pull it out of the garage, shut it off and go hook up the trailer to take it back to my father-in-law's.

Starts right up. As I position it near the trailer it dies and will only budge the starter a little before giving up. 12.6v showing on the battery.

-- >> What starting voltage is needed? Are we somehow on the cusp? I also noticed this last issue evening when running out of gas but chalked it up to a random heat soak issue.

I'm now going to look at the condition of the main fuse holder. I know that if/when that fuse is removed the engine dies. Maybe it's weak.

[Edit] This fun never stops.


Had it running from the left tank yesterday and this morning. Won't run from left tank this morning. Pull fuel line from tank: NO pickup tube. WTF. Pull fuel line from right tank: NO pickup tube. They BOTH fell off yesterday. Left pickup tube cracked. I cut a clean line and reused it. The right tank's hose has its screen missing; I looked but couldn't see it. What I did fish out was a rubber hose with different screen attached. THAT hose fell off because whomever installed it didn't buy fuel line! It swelled.

I'm off to the store for a new fuel line. I still need to find out why the starter sometimes won't budge with a full battery, and then after a minute (and about 0.1 v more) it spins right up.

Most starter solenoids have a minimum trip voltage.
This is done to prevent the starter melting from drawing too many amps
What people fail to understand is an electrical load is the constant, voltage & amps are the variables
So if the starter motor is rated at 12kw (12000 watts ) a good 12 V battery will pump 1000 amps into it
If the battery is weak and only putting out 10V then the starter will draw 1200 amps.
Amps = heat so at some level the heat will be enough to melt the solder or even the copper wires if the amps get too high
Before every one jumps down my throat, the numbers were picked to be easy to understand not to represent the actual voltages & ampages.

usually the prime suspect with poor cranking is a bad ground an the quick test is to run a jumper from the battery ground to a point near the starter .
I usually use the oil drain plug

Thanks Bert. I'll look at battery and solenoid cables in the morning.

To me, it acts like it's got "bad spots" on something (starter, flywheel magnet, I don't know.) It either spins fully and the engine is running in a second, or the starter engages and you can see the top fan turn a little and stop like something's holding it back.

Let go of the key and it "rests" (the starter lets go of the engine.) Let it wait some seconds and it might instantly spin and the engine's running normally. This is all with the battery at 12.6 or 12.7v although I think it'll work the starter at less than that also.

My father-in-law fixed a Briggs on another mower that did that. Not sure if he used sandpaper on the flywheel or WD40 or both. That one was rusty, this one's not (magnet looks decent here).

yes it could be a bad spot on the starter
No the flywheel has nothing to do with anything except to display your ignorance of magnetism on Y-tube.

I have a proceedure which I will paste under this.
Modify it to suit your situation.
Most of the time bad cranking is a failure of the decompression mechanism
Next one off the plate is a bad ground.
When servicing mowers I clean the contact points then paint over with liquid electrical tape.
It is not uncommon to find battery cables corroded well inside the insulation on mowers that get left outside as water wick up the open end of the cables.
These cable will show 0 Ohms with a meter but will not carry the heavy current needed to crank the engine.

Before you start, pull the spark plug & try to rotate the engine by hand.
No use checking the electrics if you have a hydraulic lock, seized engine or jambed belt overloading the stater motor.
Assuming the engine turns freely.

I like to start from the starter motor and go backwards .
Do the following 5 tests, regardless of the results from an or all of them as there can be more than one problem and you want to isolate where the problem lies.
Elimination of individual parts is important so you know by the end, the battery, solenoid & heavy power circuits are all in good order.

1) try to jump the starter motor directly from your car or truck.
+ on the starter first then - to a good ground near the starter ( drain plug of lift hook are good )
Starter turns = starter good

2) do the same directly from the mowers battery
Starter turns = mower battery good
No turn = duff battery, recharge it & try again.

3) check for voltage ( + 12V ) at the solenoid trigger wire with the key in start position
3a) same with ground trigger wire ( 4 wire solenoid ) or body of solenoid ( 3 wire solenoid)
( I like to test V from the battery hot terminal to ground terminal rather than ohms as they give funny readings )

4) leave ground jumper in place ( from step 2 ) & try key start.
Starter turns = power connection good but ground connection suspect ( most common )
Confirm it by trying again, extra ground removed

5) Remove the trigger ( thin ) wire / wires from the solenoid.
Ground one on a 4 wire solenoid & bridge from the hot terminal to the other.
Starter cranks = solenoid good.
Solenoid is not polarity sensitive, BUT THE WIRING IS so make sure you remove the thin control wires.
Note a thinner wire on the hot terminal is not a control wire. It is the main power feed to the mower.


From here on things become very mower dependant as starting circuits are getting changed all the time.
Basically the power goes in a loop from the hot side of the solenoid ( saves wire, no other reason ) through the fuse to the B terminal on the key switch then to the PTO switch then to the parking brake switch then to the solenoid trigger switch , easy peasy after you grow the 3rd arm. Use a test lamp and follow the power.
However a lot of mowers with a 4 pole solenoid, run a secondary ground control circuit to the ground solenoid wire through the lap bars.
Then to stop this interfearing with the normal safety function of the ground kill, it goes to a relay with the ground as the switched connection.
These are a PIA as the + control wire to the relay comes from the power loop above and the ground side of the control comes via the normal cut out functions of the lap bars.
Be very careful because if you have a system like this and accidentally send 12V down the ground loop you can fry the magnetos on some circuits.nd from the grounding bolt to one of the starter mounting bolts & paint over both with liquid electrical tape.

At all times the starter never fails to energize.

Ignored the mower for a day and a half. Today I went to the garage and metered the battery: 12.6v and guess what? The starter engaged but would only grunt. It tried to spin, like all those other times it's tried to. Engine twitched only.

Yes I can spin the flywheel by hand. Not very easily, and there's s hydraulic pump also turning etc.

Out of curiosity I look at battery voltage (at the battery) while cranking. Drops to about 7-8 volts. The Internet suggests the drop should only be to down to about 8-9 volts, suggesting the starter is asking for too much current.

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I have a 200A engine starter, the kind you wheel out on the shop floor. With POS directly on starter, NEG to battery post I flipped the switch. It was a struggle and slowly turned. Granted that assumed the battery ground cable was good but I couldn't (yet) find a good spot otherwise.

I took a break and removed both spark plugs ... I wanted to get a sense of how much quicker it would spin without them. By now, after a few more attempts the mower battery had got down to about 12.3v. With both plugs removed, the engine now spun what I'd call "normally," but not perhaps with the speed you'd expect of an engine with no compression.

With jumper cables I attached POS to starter and now had the NEG attached to oil dipstick bracket, which is about 1 inch from the secure negative cable.

With plugs still removed, my truck's battery more easily spun the engine. I reinstalled the spark plugs and ... the truck (it's running) will not spin the mower's starter. Same as with the mower's battery: the starter never fails to engage but can't turn the engine more than a grunt. That’s with my truck’s battery directly connected to the starter, nothing in the way.

Later, I connect the battery charger/starter (set to “hi”) and notice by its ammeter it’s really charging the battery. With its help the mower immediately starts easily. Like this, the charger's hitting it with just over 16v and I can hear the battery audibly protest a little. I flick the charger to "low" and it now reads about 13.9 on the battery. It still starts up easily, with a voltage drop down to 12.something at the battery.

I want a load tester for the battery. If I take it back and they see it’s over 12v (charged up) they’ll say it’s good. If I let the mower sit a day or two it won’t start on its own, even at 12.6v--that I do not understand, but I realize that's not the whole picture if it's got a weak cell. I will see if it ever fails to spin the starter with the big charger hooked up to it.

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With the charger turned off the battery quickly moves towards 13.1v and mostly holds steady, creeping lower very slightly. It'll easily start the mower on its own and without losing more than a tenth of a volt afterwards. Tomorrow I bet it'll start, but after more than a day? Doubtful.

At 12.9v the engine gives one very quick, slight hesitation after the first grunt and then spins fast the rest of the 1/2 second it takes to start the engine. At over 13v it's a continuous action. As the battery voltage drops closer to 12.5v, that quick initial hesitation turns into *all* it'll do.

Oh, and the voltage drop when starting = 2.2 volts. Sounds good to me.

With the battery at 12..9v I put the POS from the meter on the starter post and the NEG from the meter on the battery's ground post. It dropped to 10.7v while (easily) spinning.

I just did voltage drop tests on the ground side, between battery NEG post and starter housing where it bolts to the block and also a test between battery and engine block.

In both cases the results were the same: intermittently high readings that corresponded to slow/failed starting.

When it spun easily the voltage drop was no more than 0.2v
When it wanted to "hesitate/stop" the voltage drop reading was at a solid 0.5v or so.


I could run the tests successfully and run them with failures with the only variable being when I turned the key.

At first I used only the battery and it went from 12.7v (same as last night's final reading) down to 12.3v, so at that point I added my battery charger set to "low" (13.9v showing at battery now).

Even with the boost from the charger, it would still frequently have higher resistance and fail to spin the starter easily.

I'm somewhat gratified that it's failing more now; that will make it easier to diagnose. I might temporarily replace the battery cabling, solenoid and starter cable and see if the intermittent nature of this disappears.

It's getting old running tests and having the same exact tests both pass and fail.

Installed a 6 yr old battery I have from another mower. It did slightly better than the 3 month old battery. Didn't fail to start but didn't have much grunt, either. This same battery works fine in my John Deere LX176 which has now decided to not activate its starter at all.

Took the normal battery back to the store. They tested it and replaced it. Their tester is the kind that "checks CCA" (by way of measuring internal resistance?) and it only had about 240 CCA (rated for 340 CCA). It was showing 12.65v.

The new one works better, but again anything less than about 12.9 or so volts is gonna still get that first grunt before the full spin. Overall this is the best yet but I still don't know if the starter has too much resistance.