Engine runs on with Key turned off

[kasper58]

My son has a 1993 Isuzu Bighorn 3.1D that has developed an issue with the engine not stopping when the key is turned off and withdrawn.
The only way to kill it, is to remove the 15A Ign/ Eng fuse. Checked Ignition Switch with multimeter at that fuse supply side and switched key... powers on & off.
So some feed-back to supply side of Fuse?
The Alternater was replace a couple months ago with the same model and apart from that not a lot has been done to it.

[stardog]

I suspect it would be a stuck or crook fuel cut off solenoid on the fuel pump .

[kasper58]

Fuel Cut-off Solenoid appears to be fine as Engine stops as soon as he pulls fuse.

[isuzurob]

Mine is the charge relay or alternator is intermittent and if you rev it with key off it will stop

[kasper58]

Just tried that, reved to 4k and bailed.
Thanks for the try.