Fuse #2 Frustration (Class III Boomer)

[TrippleT]

Jim, sometimes you can do a voltage drop test and determine whether there is a problem in the circuit. If you hook one end of the voltmeter to the lug of the switch and the other to the post on the solenoid or what ever, you may be able to determine if there is a bad wire, or connection. But, since it gave up completely no need to go further. You can do this with any of the wires on there.
I had an old 58 Chevy one time that wouldn't start. And, every where I checked, it had 12 volts. Turned out that the battery cable was almost broke in two on the post connector. There must not have been over two or three wires that were not broken. At any rate a voltmeter still checked 12 volts. There just wasn't enough amps to make things work.
You were right it was not a dead short. Or it would have blown fuses just as fast as you could put them in. I have a short detector that you put in place of a fuse. It is nothing more than a circuit breaker and it has a meter that you run over the wire as the breaker comes on and goes off. You just follow the wire until the meter goes dead and you have found your short. SOMETIMES LOL

 

[jinman]

I'll have to keep that in mind when my 7610s gets high hours.. I wonder if they use the same solenoid.

So.. was it an insulator failure? Phenolic washer split?

Soundguy

The solenoid is just what you would expect. Its a moveable piston attached to a plunger and surrounded by electromagnet windings. An internal spring pushes the plunger and piston out when not energized.

Since the part failed over time with increasing current and heat, I think it is likely that the internal windings shorted out, winding to winding, and then started drawing excess current. The added current caused the wire to heat up and melted the potting compound until the wires came in direct contact with the grounded case. At that point, the solenoid was hot, smoking, and blew the higher amp fuse. Luckily, the lead going to the solenoid didn't get hot or I might have had a much more serious problem.

I checked the solenoid with a 12 volt battery and jumpers after I took it off my tractor. The solenoid would not operate, but I read a dead short to the case from the input spade connector and it got hot in a hurry when connected to the battery.

I'll post some pictures of the two solenoids this weekend.

 

[Soundguy]

Yikes.. a coil failure... I don't like those.. not that a 'contact' failure is any better...

Glad this wasn't a 'flaming' problem..

Soundguy

 

[jinman]

Here are some pictures of the new and old solenoid. On the new solenoid, you can just see a gray washer on the threaded end. It contains an o-ring that seals the opening when screwed into the injector pump. Evidently, the valve inside the pump is surrounded by fluid. In the third picture, you can see the internal o-ring on the cone shaped piece I cut off the back of the solenoid. That keeps the plunger sealed at both ends.

There is an internal coil spring missing because it went somewhere in my garage and I haven't found it yet. You can see the spade connector is burned and so is the potting compound. It stinks.

I checked the new solenoid with my voltmeter. It is exactly 12 ohms through the coil. That means it should only pull 1 amp. Even I can do that math.

I'll get some installation pictures tomorrow if it isn't raining. It's pretty darn simple; you don't even have to raise the hood.

 

[DocHeb]

Jim,

Do you think this might be associated with the prior Fuse #2 events described in the past for other folks?

 

[jinman]

Jim,

Do you think this might be associated with the prior Fuse #2 events described in the past for other folks?

I sure do Chris. New Holland has a new part number for this solenoid. My guess is that the coil on the new one does not pull as much current as the old one. Unfortunately, my old one was failing before I figured this out, and I could not accurately measure the resistance to ground. If someone with an older tractor could measure the resistance of their solenoid's coil, it could help us decide if this is a possible reason or just a coincidence. It's stuffed in behind the fuel filter on the back of the injector pump and not all that easy to get to. After I post pictures of my installation tomorrow, it will be easier to see where to look for the solenoid.

 

[Soundguy]

I'll check the one on my 02' 7610s tomorrow and post back.

Soundguy

 

[jinman]

After I post pictures of my installation tomorrow, it will be easier to see where to look for the solenoid.

Here are pictures of the solenoid installation. I removed the top two hoses to my FEL so I would have more room, but that's all I had to do. You can see just how easy it was to replace the solenoid.

...and it works great. It only gets warm to the touch, not hot. I mowed all day without a problem. I think I can put this problem to rest.

 

[BobRip]

Jinman, I think your increasing the fuse size helped you resolve the problem. With the lower current fuse the fuse blows before the solenoid seriously overheat from the erratic short. Once you put the big fuse in the solenoid could keep getting power and heat up, further damaging the solenoid and helping you isolate the failure. Sometimes you have to force a failure. A hair dryer might have helped.

FYI, a DC solenoid does not pull more current if it sticks open and does not "buzz". An AC solenoid does pull more current when open and if mechanically jamed open will burn up or blow a fuse. Some DC solenoids have a switch in them that opens when the solenoid engages and puts a resistor in series with it. These do pull more power when open, but they are very rare. I have never seen one.
Good job of trouble shooting.

 

[Jae]

Thanks for posting up those pics Jinman...

I was washing my machine just yesterday and was lookin for that lil solenoid in order to give it a quick inspection...couldn't find that durn thing, aparently it was directly in front of me.