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"Dieseling" older Nissan P'up

On the show today (11/22), a caller spoke about her acquired Nissan pickup running after the key was removed.



Did anyone else get a visual of “Uncle Buck’s” car like I did? (From the movie)



yep!

vac leak at the throttle shaft.lmao!

keep the shiney side up and the rubber side down.

BANDIT OUT!

The condition was common in the early '70s.

In response to the Clean Air Act manufacturers raised the operating temperatures of engines in order to achieve more complete combustion. This left enough heat in the cylinders that as long as fuel was getting pulled in, combustion sometimes happened and the engine kept dieseling.

With carburators, as long as air is getting pulled through the venturi and there’s fuel in the float bowl, some fuel will get pulled in. And combust. And keep the crank rotating. Which keeps air getting pulled in. Which keeps pulling fuel from the float bowl. And a continuous loop happens until the float bowl gets too low.

Manufacturers solved this by adding solenoids to the throttle plate plnkage, called “idle stop solenoids” that completely closed the throttle plate when deenergized and choked the engine to a stop.

In short, what Uncle Buck’s car suffered from was a real and not uncommon condition.