Wisconsin VH4D Carb Solenoid

[yankeerider]

I didn't see this item in any of the parts listings, and was wondering if any of you can tell me the purpose. I'm guessing it's a solenoid that is most likely there to shut off fuel as an anti-diesel measure. I didn't trace the wire too carefully, but I think it's energized in the run position. It's possible it's energized in the start position though, I didn't trace the other wire on the terminal to see.

The engine is running fine, I just want to understand it. This is my first experience with a Wisconsin v4. It's on a Bandit chipper.

 

[banjodunn]

G'day I think you are spot on it is an anti dieseling solenoid and should be powered up in the start and run pos



Jon

 

[brokenot]

In addition to the anti-dieseling application these solenoids are often used for, they're also often tied into the equipment's engine-protection circuitry through a Murphy switch or other similar device. The Murphy switch's start bypass or timer circuit allows the engine to start by powering up the fuel solenoid, and then once the timer elapses, the engine protection circuitry goes "into effect". If the engine oil pressure drops too low, or the engine temperature gets too high, the Murphy switch will cut the power to the fuel solenoid to kill the engine.

Some of the common wiring diagrams are available here:

http://www.fwmurphy.com/uploaded/documents/pdfs/97020B.pdf

 

[yankeerider]

Thank you both. It's interesting that I didn't find any mention of this solenoid in the documentation for the VH4D engine it's on, but it's clearly shown and described in the V465 engine repair manual. Both manuals indicate the same carburetor model- Zenith 87A8.

I looked at my machine again last night. The solenoid is wired exactly as shown in the V465 manual-in parallel with the coil. There's no "interruptor" such as for high temperature or low oil pressure. Of course, the wiring doesn't look factory, so it may have been set up differently at one time.