High Current Draw, 20Amp Fuse Blowing & Smoked LED Headlight

[CaptnDanLKW]

Brief history. 2004 Troy-bilt Super Bronco Kohler Courage 19 Engine. VERY well taken care of, but still had my share of issues. I've always been fairly capable, well read and methodical in all I do but I'm not an expert. Worked out good for me so far.
2 seasons ago - Rebuilt transaxle (not the diff) just the innards, seals and bearings.
This season, oil leak from head gasket, top case (4 screws backed themselves out, one hitting the flywheel - a well known issues) and valve cover. No case damage. So I dismantled, cleaned / soaked (shiny head and valves - like brand new) rebuilt (put in a brand new carb - didn't bother cleaning & servicing). Full serving kit. First turn of the key she ran like new.

The past two time she was hard to start and keep running. Once warmed up it was fine, so I was figuring a carb adjustment might be needed. Though at idle the engine started hunting too.

Now for the problem.
This evening, I could not get it started. Lots of cranking, adjusting choke and throttle positions, nothing. Check spark plug, fuel lines, all seemed good. Finally though to give it a shot of carb cleaner and got it to sputter to a start (barely) while adjusting the throttle. Lots of stalls, but multiple restarts and about a minute I got it running steady but noticed the ammeter pegged, then it cut out - 20amp fuse popped.
Replaced fuse, got it started (difficult again) but while messing with the throttle again, noticed the ammeter current draw decreased with engine speed (Low engine speed still had a higher draw than I'm used to - but I was cranking the starter motor A LOT so I thought the battery could be weak).
While running full speed I saw one of my nice LED headlight cut out and start to smoke. I wasn't checking voltage during all this but I surmise it got way too many volts - I mean that's what fries LED bulbs.
I disconnected by headlights to take them out of the equation and let it run a bit, still high amps and in about 2 minutes it popped again.

Winched it back up into the shed & joined this forum.

I guess few key takeaways here are:
I did remove (carefully) and upper engine - including the coil and transformer. (Carefully and retighten everything with torque wrench to spec)
It has run fine a dozen times since rebuild
Odd high current draw related to engine speed
(Probable) higher than expected voltage on the 12v DC side.

Hope someone was willing to read my story and might have some input where to go next...

Thanks all.
Dan

 

[StarTech]

First thing to do is to the output voltage of the voltage regulator. These on Kohler engines tend to go bad at anytime. Most usually just quit completely but it is possible for to fail in such a way that unregulated voltage is pass to mower.

 

[Rivets]

Post the engines model and spec numbers and I’ll find you a service manual.

 

[CaptnDanLKW]

Model is a SV590. Thanks for offering, I actually have the service manual and just noticed the very good section on testing the electrical. I will pursue that later today or tomorrow. I'm assuming its the Rectifier-Regulator without testing, so I already ordered a new one & a 20A blade type circuit breaker. I can only assume the excessive cranking damaged it. I'll post a follow-up with what I find.

Then I still need to why starting has become impossible and why it began surging at low speeds. I'll probably check the valve lashing and maybe service the old Walbro carb & put it back in. (replacement was a Chinese brand one)

 

[Rivets]

Two things come to mind with hard starting on those engines. First the choke is not closing fully for starting. Second float level is too low, resulting in a lean misturdy when starting.

 

[CaptnDanLKW]

Thanks. Choke is closing, had the filter box off while troubleshooting. New carb came pre-adjusted and worked fine for most of the season but that's on my to-check list once I solve the electrical gremlin.

 

[CaptnDanLKW]

Hey y'all, I'm back with an update - and looking for more help.

It shouldn't be this complicated...

1) New Regulator-Rectifier in
2) Valve Lashing checked - they has a little too much gap, fixed.

Same problem with starting - couldn't get it to turn over.
Took out Cheap-China-Crap-Carb, put back in cleaned and serviced Walbro.
She fired right up. Lesson Learned, and I should have known better.

BUT I still have the same problem - Dangerous High current draw and higher voltage at the headlights (i.e. 12V DC bus).
Voltage at headlight connector.
Engine not running - 12V
Engine Idle - 14.2V
Engine full speed - 15.8V

If I let it run full speed for more than a minute fuse would blow.

One other tested observation - while engine running, I disconnected the battery and the engine died (also had a lot or arcing while taking it off - proving high current draw).
1) This is NOT normal, right? A car can run without its battery. I assume the principals are the same.
2) Could this mean the 'alternator' (coil) is actually the problem? (I mean, what else could it be?)
3) Clarify for me, the transformer is still good since its providing the spark, right?

 

[Rivets]

Please post the model and serial numbers for the tractor. I want to find a wiring diagram, as something does not make sense to me.

 

[Hammermechanicman]

If you have a an anti backfire solenoid when you disconnect the battery it may be shutting off the solenoid killing the engine. Have you tested the AC voltage output of the alternator? Have you replaced the battery? Bad battery can cause high current draw. When you say transformer are you refering to the alternator stator coil or the ignition coil?

 

[StarTech]

Failed voltage regulator. From service manual.

Disregard the battery part as that is if you had a bad battery which it sounds like yours is holding a charge.

BTW many newer cars will not run with the battery disconnected any more as it is now part of the voltage regulation system. Older cars can as they had a different system. It just as if the alternator is completely shut down. It is same with Kawasaki engines where when the battery is no present the voltage regulator shuts down completely.