Faulty Solenoids?

[LN Pipeline]

The fuel shut-off solenoid on an 8.3 cummins is activated by two of these solenoids.



One for PULL, and one for HOLD. The PULL solenoid quit functioning, so I purchased another one (Cole Hersee 24063). The new solenoid worked once, then quit working. Got another new Cole Hersee, and same thing. It worked once, then quit working.

I took the old good solenoid off the HOLD wires, and wired it to the PULL wires. It worked fine. Activated it probably 2 dozen times to see if it would burn up.

I purchased a NAPA ST93 solenoid and installed it on the PULL wire. Unplugged the fuel solenoid on the pump to make sure it was not the culprit. The NAPA solenoid won’t activate at all.

The 12V activating wires light up when they are supposed to, and no shorts. The 12V activating wire for the PULL solenoid also activates the starter solenoid, and the starter solenoid works fine. The 24V wires have no shorts and share the same terminal at the starter.

Does anyone have any idea what’s going on here? It seems like I got three faulty solenoids since the old one on the HOLD wire worked fine when swapped.

Is there a better option for a 24V continuous duty solenoid?

 

[Bluox]

What are you working on that has 12 and 24 volts?
Those are not solenoids but are magnetic switches.
Bad Bob

 

[LN Pipeline]

The magnetic switches apparently were not faulty.

It’s a large Tesmec trencher. It has what I believe is called a Murphy switch. Most everything in the dash is 12 volts, the fuel shut-off solenoid is 24.

Some wiring differed from what the service manual showed. I changed it back to how it was supposed to be, and it now works.

I don’t know why the second magnetic switch was added, or why it started burning up. Until recently, it was functioning properly that way. I put an inline 20 amp fuse before the fuel solenoid to hopefully protect it.

 

[muzy]

Concentric neutral perhaps?
Cheers