Mowing Elec problem on 1850 (slope mower)

[wasabi]

Hey folks,

Long time between visits for me. life is very full.

Having a weird electrical problem with my 1850. 0nly 300 hours on the unit.
Replaced the circuit breaker with an auto store 15amp (old one was taped together to bypass - not be me )
Now she starts fine and will run for a minute or two and then the new CB trips, shutting her down.

thoughts?

 

[MossRoad]

Long time no hear!

Got a schematic?

 

[woodlandfarms]

So, are you referring to the resetable one on the dash? If so, first and foremost it is 20amp. There are two others on your machine, one 30 amp and one 50 amp. I can provide you a schematic. When does this happen? When you mow? So the solenoid on the PTO valve is a huge power draw. Have you ever taken off the coil off the PTO solenoid? You should. Then run some steel wool around the valve itself and inside the magnet.

Also, you could have a short. Its not uncommon on the terrible wiring in the PT. Usually it happens under the dash in or in the rear box. a "hair" off the wire connections will touch somehting and bring it to a stop. Oh, I have had numerous issues with the wiring at the starter solenoid.

Finally no guarantee your circuit breaker is any good. I have had that happen where the breaker was mediocre an would just release.

 

[SpringHollow]

As it happens, I have to track down what is wrong with the wiring for my starter solenoid. I have not found the time so I just keep jumping the solenoid. Pretty stupid, I know but that is the way it goes lately. I have found mice love the dash on my PT1850 and cause 3/4's of the electrical problems. They must be mutant mice because moth balls do not seen to deter them. The most interesting was when mice made a nest inside the muffler. Picture the man being shot out of a cannon at a circus!

Ken

 

[woodlandfarms]

I have an issue with my starting as well that I have yet to resolve. sometimes you turn the key, things click but hte starter does not turn over. Not sure where the issue is. Going to have to track it down.

 

[wasabi]

Thanks for the feedback. No schematic.

Will get a 20 amp breaker and see if that cures it. Wiring under dash looks ok
Also going to check the fuel solenoid. Terry seems to think that might be in play.

Oddly comforting to know this is happening to others. Misery loves company?

 

[CobyRupert]

Now she starts fine and will run for a minute or two and then the new CB trips, shutting her down.

You need to determine if a load on the system is overloading the breaker, or if a short in the system is tripping the breaker.

(Most) breakers either trip instantly when there is a short circuit (= lots of current, say >600% of the breaker rating), or trip at some (longer) time duration depending on how much they are overloaded (example: lets say it takes 5 minutes to trip when current is 125% of their rating, 3 minutes at 150%, 20 seconds at 300%, etc..)

So...it runs for a minute or two and then trips.
During this minute are you turning on a load (e.g. the PTO solenoid) that may be overloading the breaker to where it trips after a minute?
Or are you traveling over bumps, or have other vibrations that may jiggle a wire and cause a short?

 

[wasabi]

Hey Coby,

Doesn't seem to matter whether under load or not. Runs for about a minute whether in motion or sitting still....then CB pops and she shuts down.

Have tried every which way I can with same results. Haven't put a stop watch on it but I'd bet run time is consistent within ten seconds.

 

[joecoin]

Breakers trip when they get too hot. They get too hot when they draw too much current. As noted, a short (or partial short) will cause that condition.

Since it works for a little while, I'd guess the 20 amp proper breaker may be the answer.

If not, I would get the meter out and start tracing wires with respect to ground.

 

[CobyRupert]

Thermal-magnetic breakers have two mechanisms for tripping.
On a overload (lets say anywhere from 100% to 600% of its current rating) , the heat (thermal) will trip it, the time duration that it allows this current to flow until it trips will be inversely proportional to how much it is overloaded (and how fast the heat builds up.) More current = less time.
On a short circuit (say current >600% of breaker's rating), the magnetic forces around the surge current will magnetically trip the breaker very quickly (almost instantly, almost independent of time).

The bad news when diagnosing if its a short or an overload, is that one can get a short circuit (to frame), but the short circuit current flows through poor resistance (maybe it shorts to paint, or dirt covered metal, etc..) and this limits the current to below the instant magnetic trip level, and it takes a while for the breaker to trip thermally.

 

[woodlandfarms]

Here are some diagrams I have collected. These machines change over time so you cannot use these as gospel. I have also included a complete rewire diagram someone did athat one day I will use

 

[MossRoad]

Looking at that diagram, the 50A breaker only feeds the 20A breaker.

The 20A breaker feeds:
- The black wire feeds the neutral safety switch and the starter solenoid.
- The green wire feeds the fuel control and the hi-temp/lo-oil buzzer.
- Then you have the yellow wire.... YIKES! That feeds pretty much everything else.

Here's how I troubleshoot everything:

This works for pretty much everything. Software, hardware, mechanical devices, electrical devices, etc....

- Cut it in half.
- That determines which half the problem is in.
- Reconnect the problem half.
- Cut the problem half in half.
- Repeat.
- Keep cutting the problem in half until you isolate it.

I'd disconnect that yellow wire at the ignition switch and see if that kills the problem first. It appears none of that stuff is needed to start the machine. It's just lights, gauges, draft control, PTO solenoid, tilt seat, fuel gauge sending unit, oil temp and pressure sending units, and the hydraulic cooling fan.

If the problem persists, the problem is in the upper half of the diagram, which appears to be the fuel control and starter solenoid.

But I'll guess that switching your 15A breaker back to the 20A that its supposed to be may resolve it.

Anyhow, you get the gist.... cut it in half, observe, reconnect, cut, reconnect, cut, etc... until you get it down to the problem component.

 

[SpringHollow]

On my tractor, it does not take much to overload the breaker. If you are undersized, that could definitely be the problem.

Ken

 

[Rip]

From my experience on various outdoor machines, the typical pop-out breakers are not very reliable or water proof and are best replaced with marine type when a standard one starts causing problems. Also usually can go up one step w/o a safety concern....if still keeps tripping, then likely some real overload or intermittent short. May not find at typical auto supply shops though.

 

[woodlandfarms]

I am in Canada at the moment so excuse the Canadian link but this is the fuse my machine came with and what I used to replace Blue Sea Systems 2134, 2 Amp Push Button Circuit Breaker, Sports & Outdoors - Amazon Canada

 

[wasabi]

Wow. What great stuff. Google move over
Thanks to all for such comprehensive information.

I'm ordering a marine grade CB today.
Will advise after intalling that....

doug

 

[joecoin]

Wow. What great stuff. Google move over
Thanks to all for such comprehensive information.

I'm ordering a marine grade CB today.
Will advise after intalling that....

doug

Goof idea to go with marine grade, bad idea to go any higher amperage than original. IMHO.

 

[ponytug]

I always go with marine grade on my PT. I hate fixing something twice. West Marine and Del City for connectors and wire, except for the main harness, which is elevator cable.

I added a series of ground wires all tied back to a single point on the engine. The PT standard ground path is a bit convoluted, especially front to rear. You might also think of checking the alternator output. If the ground lifts, the field can invert, blowing your diodes.

All the best, Peter