Starting help/troubleshooting for newb (K181s on 875)

[Ponyboy 64]

Hello all! I've got a noob electrical/starting question (I am new to garden tractors and small engines). I inadvertently left the switch on my 875 in the 'on' position last weekend (when it started/ran OK), for a total of 4 days. Tried to start it and nothing (no starter click, engine turn, or anything...kinda like a dead battery), removed and checked the charge (it was still about 12.8V). Put it on the trickle charger and it showed it was fully charged within a few hours. Re-installed the fully-charged battery, still absolutely nothing. I was working on it last weekend and had also removed the drive belt guard, which bolts into the engine (and is the ground point for the battery), but I believe I put that all back together (in this order: block->washer->ground cable->belt guard->washer->bolt). The fact that it was starting OK and then a few days later it wasn't has me wondering if something didn't burn out while it was in the 'on' position (if that's even possible) or I didn't put something back together correctly

 

Since I noticed this, I've done the following (as noted in the title, this is a K181s engine on my 875 hydro):

 

• ensured battery has full charge
• checked all connections for good contacts (did remove/burnish the + lug and wire on starter)
• checked voltage at + lug on starter, getting 12.8V in the on position
• checked/burnished ground cable (and point on engine) from batter to engine
• replaced positive cable from switch to battery (was starting to fall apart) with new cable and connectors

 

Thoughts on what I should be testing next? 

 

Thanks!

Edited April 29, 2022 by Ponyboy

[squonk 38,844]

If all connections are ok you may have cooked the start winding out of the generator. Look at the coil on the right. do you have a voltmeter? 

 

Edited April 29, 2022 by squonk

[stevasaurus 22,229]

You may have also burnt your points and/or condenser. 

[Ponyboy 64]

34 minutes ago, stevasaurus said:

You may have also burnt your points and/or condenser. 

@stevasaurus, I just pulled my condenser and tested it with my multimeter. I set to 20M ohms, placed neg lead on wire and pos lead on casing and number slowly climbed up to around 13.00-14.00 after holding it there for about 15 seconds - I believe that passes the test if I read the internet correctly.

 

Haven't checked the points yet...will the engine not even attempt to turn over if the points are burnt? This thing is currently acting like I have a dead battery...turn the key and nothing happens.

[Ponyboy 64]

@squonk I do have a voltmeter. Checking for a cooked winding involves pulling the generator and peeking inside at the coils (I believe that's what your photo is, right)? I'll have a chance to do that this weekend.

[squonk 38,844]

Yes that's what my photo is. But before you do that check to see what voltage you have if any, at the large wire at the generator with the key in the start position. It should be a couple of tenths close to your battery voltage. If not, your losing power from the battery itself and switch. It takes 65-80 amps of power to spin the engine. If your voltage drops the amps go up and you start cooking things.

[Ponyboy 64]

37 minutes ago, squonk said:

Yes that's what my photo is. But before you do that check to see what voltage you have if any, at the large wire at the generator with the key in the start position. It should be a couple of tenths close to your battery voltage. If not, your losing power from the battery itself and switch. It takes 65-80 amps of power to spin the engine. If your voltage drops the amps go up and you start cooking things.

@squonk OK, so the large wire at the generator runs back to the switch 'starter' terminal. When I put the key in the 'start' position (all the way to the right) there is no voltage at that wire/lug on the generator. 

[squonk 38,844]

Start tracing back. You may have a bad switch. Do you have 12V at the same wire at the switch terminal? If you do you have a break in the big wire. If not, see if you have 12v at the ignition terminal of the switch with the key in the on position. If you do your switch is shot. Switch part # Cole Hersee 95521-B

[Ponyboy 64]

58 minutes ago, squonk said:

Start tracing back. You may have a bad switch. Do you have 12V at the same wire at the switch terminal? If you do you have a break in the big wire. If not, see if you have 12v at the ignition terminal of the switch with the key in the on position. If you do your switch is shot. Switch part # Cole Hersee 95521-B

@squonk Looks like the switch is bad - 12V at the ignition terminal when switch is on, and then it drops to 0 when starting. I appreciate your help and time on this, thanks!

[953 nut 51,488]

7 minutes ago, Ponyboy said:

Looks like the switch is bad

Use an automotive jumper cable from the battery "+" to the S/G "A" terminal to see if the S/G will turn over.

I think the key left on shouldn't damage anything in the START portion of the S/G, however the commutator and brushes are shared between both functions, need to look at them.     If there was current flowing through the regulator for four days it probably welded a set of contacts in the voltage regulator together. Here are a couple of interesting manuals you may want to read over.

 

 

[clueless 2,898]

First I would just hook up some auto jumper cables to a battery you know for sure is good ( your car) then to the tractor battery and see if it spins over.

[Ponyboy 64]

I am unable to do a few other tests y’all have recommended and am frustrated, not sure what’s going on (unless everything electrical has all of a sudden failed). Got some pics to help.

 

1) I’ve ordered a new switch, should be here this weekend

 

2) I can’t successfully jump my starter. When the switch is On, I have 12V going to the + luv of my starter. On the starter, I ran a jumper from the + to the - lugs (switch is On) and nothing happens. I touch the carburetor and it sparks, back to the - lug, nothing.

 

3) As suggested, I ran the jumper from the bat + to the A terminal on the generator, nothing (again, sparked when I touched the frame).

 

Shouldn’t something be turning over? 

[squonk 38,844]

If you burnt the start winding in generator then yes it  will do nothing. And touching the carb or generator body you are touching hot to ground so yes it will spark.

[Ponyboy 64]

15 minutes ago, squonk said:

If you burnt the start winding in generator then yes it  will do nothing. And touching the carb or generator body you are touching hot to ground so yes it will spark.

Yeah, the spark comment was only to confirm I had power coming out of the + lug on the starter.

 

OK, so back to your original suggestion of pulling the s/g and inspecting it for toasted windings. I'll see if I can get to that this weekend and report back in.

 

Is there anything else I should be checking on the electrical side (something I can test while I can't run the engine)? So far I feel like we've identified a faulty switch (voltage readings in the ON position when it shouldn't) and possibly the starter windings in the s/g.

[squonk 38,844]

You might be able to sniff close to the generator and smell if its burnt

[Handy Don 10,548]

I'd avoid grounding using any part of the fuel system. Sparks and gasoline vapor do not play well together outside of a combustion chamber.

Edited May 4, 2022 by Handy Don

[Ponyboy 64]

Waiting to catch a break on this 875…the long bolt holding the generator onto the mounting bracket is pretty rounded…having a hard time getting any purchase (and it feels pretty frozen on there). May see if I can just get the bracket off the engine first and then monkey with the whole assembly away from the tractor (may be time to purchase a torch and apply some heat).