843 Doesn't Shut Off Above Idle

TBigLug · Aug 30, 2020

1988 843 with Isuzu, when I turn the key off at 1/4 throttle or above the engine loses rpm's but doesn't shut down. I have to bring the throttle all the way back to idle for it to shut off. Is this normal or is there some back feeding of electricity going on? Thanks.

flyerdan · Aug 30, 2020

A quick look at the Isuzu section of the 843 book indicates that the shutdown is integral to the injector pump, unlike the fuel supply shutoff solenoid on the Kubotas.
Since it slows down a bit, I'd suspect that it moves the fuel rail rather than shutting off the supply; hopefully someone more knowledgeable will be along with an answer.

Tazza · Aug 30, 2020

flyerdan said:
A quick look at the Isuzu section of the 843 book indicates that the shutdown is integral to the injector pump, unlike the fuel supply shutoff solenoid on the Kubotas.
Since it slows down a bit, I'd suspect that it moves the fuel rail rather than shutting off the supply; hopefully someone more knowledgeable will be along with an answer.

I'm thinking the same too, if the solenoid is not pulling the rack all the way back, it's not turning all the fuel off. It could be crud stuck in the shut off solenoid so it doens't fully pull back?

flyerdan · Aug 31, 2020

Tazza said:
I'm thinking the same too, if the solenoid is not pulling the rack all the way back, it's not turning all the fuel off. It could be crud stuck in the shut off solenoid so it doens't fully pull back?

I'd bet that it was designed that way, to shut off from idle.
My dad had an old D4 Caterpillar, a '37 or '38. The throttle lever had a button on top that you pressed which allowed it to go past the idle stop to shut it down; chances are that they did the same thing, only with a solenoid and key switch.

TBigLug · Sep 19, 2020

flyerdan said:
I'd bet that it was designed that way, to shut off from idle.
My dad had an old D4 Caterpillar, a '37 or '38. The throttle lever had a button on top that you pressed which allowed it to go past the idle stop to shut it down; chances are that they did the same thing, only with a solenoid and key switch.

Thanks for the input. I think you all are right.