shuts off when jumper cables removed

[chim]

My first guess would be bad battery. "Bad" in this case is high internal resistance -AKA dead (as opposed to a short). An alternator requires outside power from the battery to generate electricity. Old cars with dead batteries and generators could be jumped and they would run unless the load on the generator was too great. Residual magnetism in a generator provides enough field strength to make it work.

Alternator-equipped machines with truly dead batteries will die as soon as the jumpers are removed because there's no way to excite the alternator.

Edit to add: A bad connection or "open" internally is possible in a fairly new battery. Several years ago I had a dead battery in my truck. That particular battery had both top and side terminals. When they ran a test on it, it was only dead on the side terminals. It tested fine on the top terminals. It was a relatively new battery and was replaced.

 

[Soundguy]

except he has a dynamo.. that's essentially a permanet magnet low output fixed field alternator. no power input needed for excitation.

My first guess would be bad battery. "Bad" in this case is high internal resistance -AKA dead (as opposed to a short). An alternator requires outside power from the battery to generate electricity. Old cars with dead batteries and generators could be jumped and they would run unless the load on the generator was too great. Residual magnetism in a generator provides enough field strength to make it work.

Alternator-equipped machines with truly dead batteries will die as soon as the jumpers are removed because there's no way to excite the alternator.

 

[chim]

except he has a dynamo.. that's essentially a permanet magnet low output fixed field alternator. no power input needed for excitation.

I thought there were generators (dynamos) and alternators. Kubota says they use alternators Any further info would be appreciated.

 

[Soundguy]

I thought there were generators (dynamos) and alternators. Kubota says they use alternators Any further info would be appreciated.

on the low end of the food chain you basicalle have a permanent magnet dynamo that makes ac volt output that is then rectified and regulated in an external regulator. there is no field control. it's a ball of wire spinning inside a fixed magnetic field ( ie.. magnets glued to the inside of the casing ). it's low output.. but fairly reliable.

then you have the standard old style DC generator. .. basically 2-3 types.. 2 brush regulated and un regualted, and 3 brush ... all have field coils instead of permanent magnets. the external regulated ones use a 2 or 3 bobbin external mechanical voltage regulator to control field current.. the contact literally vibrates open and close to power the field, and thus vary field current. as field strength changes, so does output strength on the armature. the genny has a built in comutator which is just a clever wireing scheme with brush pickups so that the output of the generator is actually DC.. it's bumpy ugly dc.. but it is DC..... other variants use a 3rd brush to control field current manually with a dial moving the 3rd brush.. some also use a 'tickle' switch tied to a lamp switch that is essentiall a fixed resistor controlled field circuit... most of those fixed ressitor types have a hi / low setting depending on lamps or switch position.. different manufacturers used different versions.

then you get the alternator.. whole new ball game.. harder to explain without getting techno-geek... but it is also variable field.. uses a stator, has a diode trio and produces essentially 3 phase ac that is rectified in the alternator. alder alts use a external regulator.. somewhat like an old style generator reg.. some use a solid state built in reg. just depends on what ya got.

I've seen tractors that use all 3. I'm not a kubota guy. OP stated dynamo. I answered based on 'dynamo'.....

 

[Leejohn]

Tractor should run even without a battery or alternator, just couuldn't shut it off with the key. Check the fuel shutoff solenoid relay-timer, it's bad. The battery could also be bad?????

 

[Tx Jim]

Tractor should run even without a battery or alternator, just couuldn't shut it off with the key. Check the fuel shutoff solenoid relay-timer, it's bad. The battery could also be bad?????

Please explain how the engine can run with no battery or alternator attached? I'm not stating your statement is incorrect I just want to know "HOW/WHAT" controls the fuel with no electricity?? Thanks,Jim

 

[Soundguy]

many diesels have a fuel lift pump built into the front end of the injection pump.

some machines also have cam driven fuel pumps, not to mention.. many times tanks are perched for gravity feed to the IP.

all depends on the setup...

as long as nothing is killing a fuel-shutoff solenoid. a diesel .. an older diesel.. don't need a battery..

With a striaght gear trans, you could park on a hill, roll her started and run all day as long as you had say.. a mechanical oil pressure gauge and not an idiot lamp... and never need a single volt / amp of electricity.. at the end of the day, fuel up and park on the hill again. I know some farmers that have tractors with bad starters that STILL do that... couple that with manual fuel kill cables like my ford 1000 series have.. and you are good to go.

 

[k0ua]

My Kubota B7500 had a manual fuel shut off knob/cable. Start her up, and throw away the key. As long as you didn't pull that knob out, she would run all day.. The instrument panel didn't work but the tractor run and operated fine.

 

[robbyr]

I think my dad's L2600 will do the same thing.

 

[Tx Jim]

But not on a Kubota B2320 which is what this thread was started about as it has an electrically operated fuel controller