Pel job

[Quattromike]

Are there any bonnet switches or low oil pressure/overheat sensors on it? Ignition modules will sometimes override these for a while during/after ignition which would give you your 30 second delay. We sometimes have similar issues with chippers that have control boxes, they can also get confused if started before allowing the pre-heat to count down to zero

Was also going to suggest checking critical engine sensors like oil pressure, temperature, fuel filter and such. Could be something there stopping the engine to protect it

 

[Smiffy]

Tbh if it runs fine without the stop solenoid being wired in correctly just run a new wire to it with either a switch on the dash or piggy back of the live on the ignition switch
I have done this with a thwaites that would randomly cut out as you drive around
Just stick an in line fuse holder in and by passed everything straight to a spare switched live it had on the back of the ignition barrel

 

[Steve]

Tbh if it runs fine without the stop solenoid being wired in correctly just run a new wire to it with either a switch on the dash or piggy back of the live on the ignition switch
I have done this with a thwaites that would randomly cut out as you drive around
Just stick an in line fuse holder in and by passed everything straight to a spare switched live it had on the back of the ignition barrel

Problem is if you over ride say a low oil level or low oil pressure switch the consequences could be costly. I would investigate further if it were mine.