Why does my engine still try to run after I shut it off?

Dieseling or engine run-on is a condition that can occur in gasoline powered engines, whereby the engine keeps running for a short period after being turned off, due to fuel igniting without a spark.

Causes of "running on" (continuing to run when ignition is turned off) are most commonly these:

Air leak -- leak at manifold gasket, carburetor gasket, or any of the assorted vacuum diaphragms such as the distributor, air cleaner flap motor, or carburetor choke-pulloff. See Vacuum Leaks

Idle too high. Should be 750 rpm or lower. See Carburetor_Adjustment#Idle_Speed_and_Mixture_Adjustment

Open Chamber type cylinder heads. While these reduce emissions, they are more susceptible to run-on. To reduce run-on, Datsun fitted carburetors with an anti-diesel valve to these engines.

[edit]

How do I stop the engine?

See the causes and solutions above. But for now, you can easily stop the engine:

set hand brake
push clutch pedal down and put in high gear
turn key OFF and at the same time let the clutch out slowly. This will stop the engine

Retrieved from "http://datsun1200.com/modules/mediawiki/index.php?title=Dieseling"

This page has been accessed 7,504 times. This page was last modified 11:42, 16 May 2018. Content is available under Datsun 1200 Club.