3208 cat motor

forgot to include the solenid works fine when not bolted to the fuel pump

Hi Boots,
it is not unknown for moisture to get into the shut off housing under the solenoid.
Squirt some CRC or other dewatering-lube spray into the shaft bearing areas and using your finger work the shut off lever back and forth some until you feel it move easier.

It also sometimes needs the shaft to be removed and the seal run area polished to an almost mirror finish with very fine polishing paper as the seal lip drag can stop the lever dropping back down to the run position.

Also check the solenoid plunger for free movement or binding on the sides of the lever slot, once the solenoid plunger retracts to the Run Position, it is only the Gov. spring force that moves the system of linkages to the Run Position--there is a lot of mechanical disadvantage up to the shut off lever and resistance here can stop the Run Position being achieved.

Water is the biggest enemy of these Sleeve Metering Fuel Systems. The pump body is full of fuel at all times and moisture laden fuel can build up rust nodules inside the pump hindering its smooth operation.
You may need to remove the top cover from the pump housing if the above is not successful and slide the racks back and forth and operate the linkages by hand to free them up further.
Hope this helps.
Cheers,
Eddie B.