B1700 keeps blowing 30amp fuse

[Sandypossum89]

1996 B1700
The main 30 amp fuse near the starter keeps blowing on me when I try to start the engine. However I am not 100% sure which key position blows it, run or start. I believe it is start but I don’t have any more fuses handy to double check. Here is what I have done so far and the results.
-unplugged the voltage regulator, results in the starter just spinning, not throwing out the bendix to grab the flywheel.
- replaced the regulator with a cheap one off Amazon and the internals sizzled and melted when I tried to start. Fuse did not blow
-replaced the glow pugs also with cheapo’s off of Amazon.
- regulator plugged in fuse blows
- reg unplugged same spinning of the starter.
-To test the starter I jumped the solenoid with a wrench and it just spins, does not engage throw the bendix and engage the flywheel. Same results regardless of key position.
Also to note I jerry rigged fuse holder on the slow blow socket to use cheap automotive 30 amp fuses so not to waste 6$ every time it blows. But that shouldn’t make a difference in diagnosing the issue I wouldn’t think.
I’m beginning to think I have a bad starter, as I have never encountered one that won’t engage when you jump the solenoid posts.
Of course there are no obvious shorts in the wiring that I can see.

 

[Sandypossum89]

If it is relevant all three glow plugs were stuck in the head with carbon buildup and the tips on two of them were slightly swollen.

 

[Captain13]

If it is relevant all three glow plugs were stuck in the head with carbon buildup and the tips on two of them were slightly swollen.

1. Check the wire at the connector that goes to the glow plugs. I have seen those short on other tractors and cause the fuse to blow. Maybe disconnect the glow plugs and see if that is causing the problem. If it is, the short is in that part of the wiring.
2. Trace from the switch to the starter and look for loose, corroded or wires that have been chaffed and causing a short.
3. It’s odd that the bend is doesn’t engage when you jump it with a wrench.

 

[Russell King]

Glow plugs are bad and need to be replaced if you have not gotten to them yet. No idea if that is the problem but they sound like they need replacement from your description. Use Kubota brand or NGK (same as the Kubota)

 

[Dave_eng]

Typically the your results of your jumping the starter ( just spinning) is because you are not doing the jump properly.

Study this image and confirm you are doing it as shown. I think you are jumping the two large terminals on the solenoid which does not pull in the bendix.

A big caution, if you do the starter jump properly, you are bypassing all safety features and can get run over or have a runaway tractor. best to have someone on the seat with the brakes applied.

My comments re the slow blow fuse blowing:

Unlike other tractors on the same time era, yours has a light bulb that turns on when the glow plugs are heating. Other models used a glow indicator which was a coil of glowing wire.

The engine stop solenoid is powered to allow the engine to start and keep running. Other models do the opposite which confuses some who offer advice.

The engine stop solenoid has two internal coils of wire. One coil is strong, draws a lot of current and is only powered when the key is in the START position. The pull in coil as it is called moves the internal hardware so the fuel can be delivered. When the engine starts and the key is returned to the ON position, the weaker hold coil takes over and holds the engine stop solenoid in the run position.

The pull in coil is connected to the same terminal on the starter solenoid as the starter motor itself.

Disconnect all glow plugs at the engine. Unplug the engine stop solenoid. Now see if the fuse still blows. You can use a lower amperage fuse for these tests.

If the fuse does not blow you are now determining that either the GP's or the engine stop solenoid is the cause of the fuse blowing.

p.s. I recall that the Kubota WSM wiring diagram has an error. It shows the engine stop solenoid pull in coil is not powered through the 30 amp slow blow fuse. If the stop solenoid is still blowing the main fuse this would suggest my recollection of a wiring diagram error is true.

Dave M7040

 

[Sandypossum89]

I replaced the starter and had the same scenario happen
Test voltage at the battery during attempted ignition and it dropped from 12.3 to 9v
Hooked it up to a different battery and it started right up. The strange part is, why would a bad cell in a battery cause a fuse to blow?

 

[i7win7]

deleted incorrect info -

how about a limited current fuse that doesn't blow? 12v incandescent light bulb as a fuse replacement. A 60w bulb will pass 5 amps. If you have a short to ground, light burns at full power. When you find/remove short lamp is dim or goes out. You may want a few lightbulbs before LED's replace everything.

 

[lugbolt]

The 30A fuse isn't in the starter motor circuit, only in the solenoid circuit thus the starter MOTOR won't cause the 30A fuse to fail. Solenoid can, though.

Glow plugs are on anytime the engine is cranking-so that's a possibility that you may have one or more failed glow plugs. Disconnect the wire lead from the glow plugs and try cranking without the wire attached. No fuse busting? You have a bad glow plug-or two-or all three. Fuse still blows? Look at your wiring diagram and see what's on your starting circuit. Keyswitch, wiring, starter, switches, etc. It's a pretty simple system best I remember but as with all electrical problems it's easy to over-think it.