Trouble Shooting Genset Fuel shut off Solenoid

[Max Simmons]

Yesterday I replaced the raw water impellar on my Onan 8.0 MDKD. To make it easier to get at the pump, I removed the fuel shut off solenoid. It was pretty straightforward, 3 wires and a couple bolts. After I put everything back together, the solenoid would not operate. I took pictures of the connections to be sure and not screw up which wire went where. Connections all appear clean and tight, and the solenoid worked fine before, although its been sitting for about 4 months since it last ran. I was able to hold it in the run position and manually shut it down.
Looking for suggestions on how to diagnose this. Thanks

 

[utclmjmper]

If the solenoid works mechanically, ( and it appears that it does,) then it has to be the wiring snafu.. Carefully recheck your image..>>>Dan

 

[jleonard]

clean and lightly lube the shaft.
And check that the connections are clean.

 

[chiropaul]

Also, if the bracket holding the solenoid has some play in it, position the solenoid so that the shaft moves in and out without binding anywhere before tightening it down.

 

[ABfish]

If it's a three-wire solenoid, then it has a ground lead, a pull lead and a hold lead.

The pull lead pulls the shutoff shaft back. It's only energized when the starter is engaged.

The hold lead is energized when the key is switched on. It keeps the fuel solenoid retracted as long as the engine is running or the key is switched on.

If you need to troubleshoot, I highly recommend a Power Probe diagnostic tool-

https://www.amazon.com/Power-Probe-...ocphy=9010003&hvtargid=pla-376660908451&psc=1

 

[Greg QS]

Check to see if it grounds though housing and clean connection points. Also some time when you take off the stab connectors you loosen them up. And sometimes you pull the wires loose in the crimp.

 

[Max Simmons]

If it's a three-wire solenoid, then it has a ground lead, a pull lead and a hold lead.

The pull lead pulls the shutoff shaft back. It's only energized when the starter is engaged.

The hold lead is energized when the key is switched on. It keeps the fuel solenoid retracted as long as the engine is running or the key is switched on.

If you need to troubleshoot, I highly recommend a Power Probe diagnostic tool-

https://www.amazon.com/Power-Probe-...ocphy=9010003&hvtargid=pla-376660908451&psc=1

Thanks for the info. The more I ruminate on this, I think I must have screwed up the ground. I'll be doing more investigative work over the weekend.

 

[PM]

Solenoids are easy to bench test.

pete

 

[Max Simmons]

I thought I'd circle back to this as it may help someone else in the future. After more testing and confirming that the wiring was correct, I finally figured out what I did to screw it up. Somehow, as I was removing the solenoid, I must have tightened the threaded rod that attaches to the fuel shut off, thus shortening the amount of throw. The solenoid plunger was sticking too far out to operate. Simple adjustment and all is good.

 

[High Wire]

Thanks for closing the loop