Solenoid on the miller bluestar 2 E AC/DC

[rocky top]

My solenoid is not pulling the piston far enough in to throttle the engine to 3000 RPM ( welding power). When I flip the power switch on I can see the piston move a little, but does advanced the throttle at all. I have cleaned the piston and solenoid and piston moves freely. Has anyone had a solenoid go bad?

[duaneb55]

You can check the throttle solenoid coil resistance between leads #37 & #38.

Should be approximately 5ohms with the plunger extended and approximately 24ohms with the plunger pushed firmly all the way in. My guess is the pull winding has failed and you'll probably get the 24ohms reading with the plunger extended or pushed in.

The hold windings don't have sufficient force to pull the plunger in against the speed spring tension which is why it will only move slightly. If you manually push the plunger all the way in to increase engine speed to weld RPM with the switch in the AUTO IDLE OFF position the plunger should stay in if the hold windings are good. However, the solenoid is still defective if the above test indicates the pull-in windings have failed.