No start, and electrical strangeness

[mudpie]

Howdy. First post, so I hope it's in the right place. I don't know if I should post in the repair section, or the brand section.

I'm trying to get my mothers mower going...Craftsman DYT4000, 18.5hp Intek plus. Last year she had a starting problem, and I traced it to a bad starter solenoid. I replaced it with a used one off a parts mower to get through the last month of the season.

So now it's spring, and time to get the mower going, but the solenoid just clicks. I also notice the starter is smoking. I bought a new solenoid, and had the starter tested at the place I get my parts. They say it's fried, so I take the starter off the same parts mower I've got laying around.

I put on the used starter, and the new solenoid, and it still just clicks. Ok, so probably another bad starter. In the process of checking though, I notice I'm only getting 6v (+/-) to the starter when I turn the key to crank it. I've got 12v going to the solenoid, but not coming from it. I switch back to the old solenoid, still the same reading.

I've now very quickly exceeded my level of knowlege with regard to mowers. Any thoughts appreciated.

 

[ILENGINE]

Either you have a bad connection between the solenoid and starter, or the ground wire from the battery and where it hooks to the mower has a bad connection

 

[Rivets]

ILEingine is correct. I would jump start directly to the starter to confirm, with the parking brake engaged.

 

[mudpie]

I checked earlier, and just now to verify, and this is what I've got...

12.48v at the battery, + to -
12.48v between the battery + and multiple places on the frame
12.48v at the battery side of the solenoid
5.47v at the starter side of the solenoid
5.47v at the starter

I also have continuity between both ends of the cable that goes from the solenoid to the starter. All those numbers fluctuate a little, but I think my battery is getting drained as I keep turning the key more and more to check stuff. I checked a couple hours ago and got readings very close to those.

 

[mudpie]

I tried to jump the starter directly, since I'm only assuming it's bad. Using jumper cables from the battery, I clamped the negative to the frame, and the positive to the post on the starter. It didn't engage, and sparked as if I'd clamped a positive and negative together.

 

[Rivets]

That tells me that the starter is shorted directly to ground. Bad starter? If, the starter didn't spin up and engage. It will give you a good spark when doing this test.

 

[mudpie]

When I had the first one tested and found it was bad, I ordered a replacement. I put this used one on just to see if maybe I'd get lucky temporarily. Obviously it's dead too.

I'll see what happens with the new starter, hopefully tomorrow.

 

[mudpie]

It occurred to me that there was one more check I didn't do....

I'm getting less then 6v at the starter, but when I disconnect the cable from the starter, I get 12v at the end of the cable. When I reconnect it, I only get 6v again.

Obviously something with the starter, right?

 

[Rivets]

You are correct.

 

[mudpie]

I haven't got my new starter yet, but I had a thought....

I've got an 11hp industrial B & S on a water pump, and it's got what appears to be the same starter. I'm guessing there's not much variation. That motor cranks fine, so I pulled the starter and put it on the mower.

Now that it's on the mower, the mower cranks, but very slowly, and not more than a couple revolutions. It seems that compression is overpowering the starters ability to crank. If I let it sit a minute, it cranks again, presumably after compression has bled off. However, it still only cranks a couple revolutions again.

I'm lost. Again. Any thoughts appreciated.

For what it's worth, this mower ran fine last year, but it has now been sitting for 7 months. Also, the battery is new.