<VV> run on

[Jim Burkhard]

Mike is right... I kept waiting for the original poster to be a little 
(OK, a LOT!) more descriptive with repect to his problem.  People are 
reading his post at least 2 different ways:

1.  Does the engine buck and snort and cough for a second or two (or 
more!) after the key is turned off?  This is "dieseling" and involves 
the engine running WITHOUT spark -- it's purely pre-ignition -- hot 
spots in the chamber.  A build up of carbon in the chambers can be a 
cause (as can a too hot spark plug) and low octane fuel will 
accentuate the problem, as will a too-high idle speed. Spark advance 
isn't a direct effect (becuase the ignition is off, there is NO 
spark!), but an over-retarded hot engine will be more prone to run-on. 
Likewise, an over-advanced engine that is knocking immediately before 
key-off can have hot spots in the chambers.   If you aren't beating on 
the engine just before you shut it down and see this problme, it isn't 
an overadvance issue, though.

2.  Other folks took the "engine won't shut off" description to mean 
that the engine idles INDEFINITELY smooth as silk just like the key 
was still in the "ON" position.  Sparks are firing, even though they 
shouldn't be and you've got an electrical problem causing it -- power 
feeding back somewhere to keep the coil alive even after key-off.

Now, which is it?   I think we need a much better description of 
everything that happens...

Jim Burkhard


Mikeamauro at aol.com wrote:
> 
> 
> "...when I turn the ignition off the motor keeps on running. How can  I 
> rectify this?..."
> 
>  
> I respond to this "Run On" complaint, thinking the poster was  complaining 
> about a classic "Run On" condition... i.e.: the power to the  ignition system is 
> removed, but the engine keeps running due to a  "dieseling" situation. I've 
> watched the ensuing posts, and still haven't seen a  positive identification of 
> the underlying cause. Is the problem true  dieseling, or is power continuing 
> to be supplied to the coil after the key is  moved to the "OFF" position. 
> Depending on the actual cause,  the pathway to solving the problem is drastically  
> different.     
>  
> Mike Mauro