Engine doesn't want to shut off

[Dibsen]

I haven't read about anyone else having this problem. when the engine is good and warm after a drive, when I turn the ignition off, the engine will continue to turn over at a slow, rough pace before it sputters out.

So I will either leave the trans in gear and slowly let the clutch out to stall the motor or I will pump the throttle to kill it.

I can take some pics tonight.

[o2batsea]

Timing's out. The phenomenon is known as "dieseling". The engine is running backwards on fuel left in the float bowl.
It could also be that excess carbon is making a "hot spot" in the combustion chamber(s). Thus a properly timed engine can still run on even tho all the external adjustments are good.

[cedryck]

Mine 2.25 petrol will diesel on and shudder, timing is right on, just another natural thing on engines, not something that is terribly harmful to an engine, it does demonstrate good compression. cheers,

[SafeAirOne]

just another natural thing on engines

I'm not sure I totally agree with this assessment.

You've got to ask "what is the ignition source?" when the engine is running on and on long after the coil is de-energized.

The source of ignition is often some abnormally-hot item in the cylinder. It's just a matter of finding out why that item is abnormally hot and correct that issue.

Having said that, didn't they put an anti-run-on solenoid on some carbs to kill the fuel source to prevent post-shutdown dieseling? I guess they threw in the towel on actually solving the root of the problem...

[martindktm]

I had had a few Renault 5 car when I was younger and they had a Weber double barrel carb that Had a shuch solenoid if I remember well....

[Boston]

Classic dieseling. So check timing etc.

[Revtor]

They did install an anti-dieseling solenoid in the US trucks that were getting the smog setup. The solenoid would cut off the idle circuit so your engine couldn't. This solenoid, PCV valve, hoses connecting this to that, another control valve-ey thing on the carb etc, were all part of the various emissions systems implemented through the years.


Your idle may be set a bit high, and/or you may be sucking oil in through the intake somewhere.

~Steve

[Les Parker]

RN has sold the Solenoids for both Zenith and Weber carbs. I used to, many moons ago, work for a Renault Dealer in UK and we had the darndest time stopping the 9's and 11's from "running on" after unleaded fuel was mandatory. Lead substitute pellets used to be offered as an alternate to the solenoids. I'm of the belief ethanol also plays a part in this scenario.

2p