Cummins Diesel Fuel Shutoff Solenoid Repair/Cleaning

My Motorhome wasn't starting at seemingly random intervals.  We'd take it on a trip to the beach and it would run fine, but if you stopped anywhere it wouldn't restart.  It reminded me of a vapor lock on a gas motor.  I grabbed the manual and started reading.  On my mechanical injection 8.3l cummins diesel the solenoid is the device that turns the fuel flow on and off.

Check out this You Tube video for it in action:  http://www.youtube.com/watch?v=MVQdOi3nBhs

One time when it wouldn't start I checked and the solenoid wasn't in the "Run" position.  I put the key in the ON position, ran back and lifted the solenoid into the run position.  It stayed in the RUN position so we continued on our trip.  After the trip I went to buy the part at NAPA . . $230.00 for the part!!!!  I looked online, $180.00 for the part!!!

Since I knew it was just a solenoid, I decided to take a look at it and put a ohm meter on the pins.  There weren't any shorts, when cold at least so I assumed that it worked correctly electrically.  When I started to move the solenoid pin, I noticed it was "crunchy".  So I took it apart . . . . look what I found inside . . .

Click the pictures for bigger photos . . .

The black gravel and dust stuff was inside the bore of the solenoid and I think it was binding up the piston.  The gravel stuff looked like pumice, but it didn't crush between my fingers.  Perhaps it was a pad at the base of the bore to absorb the impact of the piston in the bottom of the bore, but disintegrated???

I examined the piston and bore and found that the piston was scuffed or surface rusted in an area, but the hard chromed finish was perfect otherwise.

I cleaned up the piston with my Dremel Tool, a polishing bonnet and some compound.  It cleaned up perfectly.  I also used the bonnet inside the bore and polished off the rust and minor pits.

(If you ever need a Dremel Tool serviced, send it to Rob Dremel at the Palm Springs Service Center.  http://www.dremel.com/en-us/customerservice/ServiceAndRepair/Pages/default.aspx)

I blew everything out, the rubber boot looked great, so I reassembled it with a new zip tie.  The bore no longer was "Crunchy".

I reinstalled in in the Motorhome, adjusted the nut to set the fuel flow to full flow when fully engaged.

I've taken a couple of trips and put about 750mi since the rebuild/repair and it seems to work great!!!

Update 2/27/2011 - Still works great, not a problem since.  About 3000 miles on it so far.

Todd