Why does the engine die a few seconds after being turned off instead of instantly?

[pinolobu]

This does not happen all the time; about once in a few days.

After killing the engine, sometimes it does not die immediately - the engine would shake and shudder first, before coming to a complete stop.

If I attempt to start the engine immediately after that, it would be quite difficult - i suspect it's due to "overflow" because I can smell petrol if I open the hood. Waiting for some time (20-30 minutes) would solve this "difficult to start" problem.

What's going on, and what would you advise me to do?

PS. I wanted to ask the question here first before going to the mechanics, at least I am armed and ready with some knowledge.

Thanks for any info.

P.S. the car is a 9-yr old manual transmission Iswara Aeroback.

 

[edwin_lcw]

mostly happen to carbies ...... your driving a carburetor car ? i think the auto choke guar ? ..... just a guess .....

 

[lozo]

when you shut off the engine but it still run, this thing is called as dieselling. the fuel self ignites which causes the engine to run without any spark ignition.

 

[gohkokeng]

dude pinolobu i got the problem also before 3rd service 10,000km of LMST

about 9k+ cause i seldom use car.....got this problem due to long time delay no service.

shut down engine then shake bbrrr......... for 1-2 seconds right?

funny is when i park very close to my brother's car then shut down engine and shake......he shocked tot i kiss his car.....hahahahahaha!!!!!!

after 3rd service + i personally take there to change 9.2mm silicon spark cable + Bosch Super 4 spark plug. This problem totally no more already + very stable idling RPM once start engine.

 

[Doink]

mostly ppl say this is due to the car got overheat before...so the gasket kong already and the cooling system not so good...mine was the same...4G13...till now i didnt overhaul it...just dont so fast turn off after revving on the street or racing...i speed and rev kau kau on the highways...then drive slowly after exiting the highway heading towards my house to let the engine cool down...when parked the car then will wait around 5 seconds after off aircond then only off the engine...so far so good...no more that symptom...WELL IT WORKED FOR ME...TRY IT!!!

 

[gohkokeng]

mostly ppl say this is due to the car got overheat before...so the gasket kong already and the cooling system not so good...mine was the same...4G13...till now i didnt overhaul it...just dont so fast turn off after revving on the street or racing...i speed and rev kau kau on the highways...then drive slowly after exiting the highway heading towards my house to let the engine cool down...when parked the car then will wait around 5 seconds after off aircond then only off the engine...so far so good...no more that symptom...WELL IT WORKED FOR ME...TRY IT!!!

DUDE! u reminded me something

ya when i went to 3rd service....my coolant already empty until kering.....
u said overheat......i think that's the problem of shaking when turn off engine for carb. no doubt already.....gasket kong? so serious meh? but after the service is nothing liao....they fill up the coolant and change the whole radiator coolant for me.

was thinking to tahan until service give them refill the coolant.....haha forgot to refill myself........furthermore Malaysia too hot.....

 

[pinolobu]

Thanks for all your input. I hope to get the car checked out soon.

 

[mike5220]

There are many reasons why a car would run on. Higher than usual temp, high compression, fouled plugs, coked up valves/piston heads. Mostly related to heat. Eg, if pistons coked up & is hot enough, it can cause compressed mixture to ignite without sparks & the engine would run on (dieselling). Poor air/fuel mixtue can also cause it although usually you'd get more pre-ignition (knocking). Get it tuned as well.

Poor fuel grade or lower octane will also cause it.

Hope you solve it.