My '94 fuel shut-off solenoid is requiring frequent assist to open. Holds fine one helped up. How can I confirm bad solenoid vs. flakey relay or low voltage (wiring) issue. Just want to make sure before committing to the big $$$ purchase. Any recommendations on suppliers for the solenoid if I do need one? Prices range from $160 to $350 for "same" part.

 

Pull the harness out, grab a multi-meter, and check all 3 lines. One will be a ground. One will be a low amperage, the other higher. The higher one is the lift wire, the other is the hold wire. If there's no lift amperage (only comes on for a few seconds, so you'll need to watch it while someone else cycles the key), replace the relay.

 

i had the same problem. the dust boot that covers solenoid got caught up in solenoid and burnt the relay up. to diagnose i took the heater relay thats right next to the solenoid relay on the firewall and swapped em. it worked. so i had a cheap 30.00 amp relay in the toolbox and used it for about a couple of months until it flaked. i had to get a 70 amp relay to handle the load.
the 70 amp relay can get pricey especially from napa. good luck.

 

Their are 2 coils inside the solenoid. A pull coil and a hold coil. The hold coil is energized with the key on, the pull coil is energized when the starter is engaged via the relay on the firewall.

If their is nothing binding up within the kill linkage/solenoid itself, double check the blue wire running to the drivers side battery (typically rots off!) and if that checks out good the next and also common culprit is the relay on the firewall which can easily be checked with a multimeter.