CH740 in new CC XT3 surging & dies (FIXED!)

stembridge

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I'll have to take the battery into town to have it load tested - all I have is a basic 'toaster' tester, which I think isn't meant for small batteries.

The symptoms are such that the engine starts stumbling off and on, usually after running for 15-30 minutes, but sometimes immediately after start, as is my current case. If it runs, it might not kill the engine during one mowing session, but over several sessions seems to get worse until it dies and won't restart (no click from solenoid, no starter rotation, lights and other electrics work, tho). It's not consistent in how and when it dies, at least I've not recognized any pattern yet. It has done this since new, although I didn't recognize it as an electrical issue for some months.

The factory battery was dead when I bought the tractor (had been sitting on their dealer floor for almost a year), so they put a new battery in when I picked it up. One thing I have observed is that the battery seems to lose charge slowly in-between uses. I've seen it get as low as 11.4 volts, which is probably low enough to cause the issues I'm having. Recharging does not correct the stumbling/dying problem, however.

The dealer from whom I purchased is 5+ hours away (they had one of the last XT3s left anywhere close to me), so taking it back there isn't viable. I did take it to a local dealer in the Spring (True Value) that sells a limited range of CC as well as does general lawn equipment repair. Naturally, it ran perfectly for them! He went through the wiring and said he replaced a couple of “sketchy” connectors. Ran fine all summer after that, but started acting up again after I pressure-washed it a couple months ago (not convinced there is any correlation there). Tractor is stored in a garden shed, so it doesn’t sit out in the weather.

I downloaded the 2000 series service manual yesterday, as it seems to be very similar to the XT3. It was very helpful to better understand all the components and how they're wired together. I’m going to run some additional tests today based on what I’ve been reading.

es
 

stembridge

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I've run all my tests on the RCM and safety switches, and everything checked out okay - a real head-scratcher.

One of the yootoob vids I looked at last night showed a guy that used jumper cables (negative side only) to jump directly from the battery (-) to the engine block to get around a bad ground issue. Decided it wouldn't hurt to try myself, despite my ohmmeter suggesting no issues there.

Danged if it didn't start right up!

Just finished lunch, so heading back out to pull it out of the shed, jack it up and see if I can find the battery grounding point and clean that up. I think I may go ahead and make up a direct ground strap, too. Hopefully this will be the permanent fix!

es
 

stembridge

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New ground strap is installed, direct from (-) to the engine block. Starts and runs fine! I drove it over to my garage and jacked it up to see if I could locate the frame end of the battery ground cable, but it still eludes me. Probably buried inside the frame under the operator platform.

I'll dig out the leaf vac tomorrow and give it a good stress test and will report back with results.

es
 

Tiger Small Engine

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New ground strap is installed, direct from (-) to the engine block. Starts and runs fine! I drove it over to my garage and jacked it up to see if I could locate the frame end of the battery ground cable, but it still eludes me. Probably buried inside the frame under the operator platform.

I'll dig out the leaf vac tomorrow and give it a good stress test and will report back with results.

es
“Toaster” battery resistance tester is what I use on 250-350 CCA batteries to test. Sounds like ground issue may have resolved the problem. Now that you have experienced first hand how frustrating some of these issues can be for a shop to diagnose and fix, you can appreciate what they go through. Although in this case, experience would have probably sped up the process. Using jumper cables for good positive and negative connections is something I use from time to time to eliminate electrical problems.
 

stembridge

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I won't call this a permanent fix until I've run it numerous times without issue. I'll update this thread occasionally, hopefully with positive results.

Many, many thanks to everyone for their input!

es
 

stembridge

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IMG_5680.JPG

Ran the tractor with the DR vac for a couple hours today and not a hiccup!

IMG_5679.JPG

I think I found where the battery (-) terminates, at the base of the starter. Didn't pull it off yet, as I needed to get the yard done. Doesn't appear to have any corrosion on it, but we'll see what I find when I remove the bolt.

es
 

slomo

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Look up on youtube the big 3 or big 4 upgrade. Talking about improving the wiring in cars and trucks with stereo systems pulling massive amperage. All circuits need testing UNDER LOAD. Engine off testing gets you na-da.

Need a good ground strap from the engine, frame and body. All tie together to the - battery post. The - battery post is the BEST ground location on any vehicle. Star grounding washers, buss bars and heavy cable are your friends.
 

stembridge

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Ran the tractor with the Johnny Bucket for ~30 minutes moving some topsoil into our kitchen garden area, no issues.

IMG_5717.JPG

@slomo - my sleeve hitch and bucket lift motors are grounded directly to the (-) terminal for the reason you state. I've seen folks discussing the wiring upgrade on car sound systems, which makes a lot of sense.

es
 

Tiger Small Engine

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Ran the tractor with the Johnny Bucket for ~30 minutes moving some topsoil into our kitchen garden area, no issues.

View attachment 67241

@slomo - my sleeve hitch and bucket lift motors are grounded directly to the (-) terminal for the reason you state. I've seen folks discussing the wiring upgrade on car sound systems, which makes a lot of sense.

es
Glad you got it fixed. I have seen loose engine bolts several times this year on customer equipment. Even with the ground on the loose engine bolt, the mower still started and ran. If in doubt I use sandpaper and wire brush to clean up corrosion.
 

slomo

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Typically you want the starter body grounded to the - post. Why? Starter on many vehicles is the biggest amp draw on said vehicle. Now car stereos car easily surpass a car starter so things change with a mega car system. Glad to hear you got her fixed.
 
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