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BN1 - Engine doesnt want to shut off

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BN1 - Engine doesnt want to shut off
#1
andrew54 Andrew P
Mississauga, ON, Canada   CAN
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Hi All,

Once the engine has been run and is warm, i find that more often than not it does not want to shut down. It will buck and run for a few seconds after key is turned off. I've read few threads about the issue, but never a solution.

Just want some ideas; Was thinking

- Timing issue
- Plugs
- Mixture

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Re: BN1 - Engine doesnt want to shut off
#2
PAN Avatar
PAN Alwyn Keepence
Ipswich, Queensland, Australia   AUS
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1954 Austin-Healey 100 "Pan"
1954 Austin-Healey 100
1960 Austin-Healey Sprite "Jette"
G'day Andrew,
Your engine is running-on. This is often caused by too fast an idle speed or a hot spot in the combustion chamber igniting fuel after the ignition is switched off.
It is very bad for the engine so try to avoid letting this continue. Easiest way to stop it is to put the car in top gear and let the clutch out to stall the engine.
Check the idle speed, which should be between 600rpm and 800 rpm.
Low grade fuel can also cause running on.
Cheers,
Alwyn

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about 1 week and 1 day later...
Re: BN1 - Engine doesnt want to shut off
#3
Highlands Guy Avatar
Highlands Guy Geoff G (Disabled)
Bundanoon, NSW, Australia   AUS
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Hi Andrew, I am partly in agreement with Alwyn regarding te idle speed if you can get to 500RPM, that will help. Where I differ with Alwyn is using the transmission to stop the engine, in my view this puts considerable strain on the back axle and the gearbox (unless you use top gear with the clutch depressed). May I suggest you richen up the carburetors slightly or as a friend and Healey owner used to do pull the chock out to flood the combustion chambers (Remember the ignition/spare is not firing). Something I have found helps also is buying the right fuel octane.....In the interest of the pock many folks buy 91 octane but if you know the compression ratio of your engine and it's 9;1 or over use 98 Octane.........our car is 10.3 Compression ratio and we use 98 Octane which when fresh for the pump works really well in stopping the "dieseling"......One last point when you stop,. let the engine idle for a 30 seconds or more to cool the combustion chamber down a little before turning off the ignition - this is just a habit to remember

Cheers
Geoff

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Re: BN1 - Engine doesnt want to shut off
#4
andrew54 Andrew P
Mississauga, ON, Canada   CAN
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Thank you both for suggestions - I haven't driven the car since making this post, but i will try and report back.

I can say that i always use premium fuel so i will say that should not be the issue. In Canada that is 91/93 Octane, which translates to 95/98RON. Letting the car idle is a great idea too.

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Re: BN1 - Engine doesnt want to shut off
#5
maserich Avatar
maserich Rich Heinrich
Scottsdale, AZ, USA   USA
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1926 Chrysler Imperial
1931 Studebaker Garford
1956 Austin-Healey 100
1960 Austin-Healey Bugeye Sprite    & more
I have had a run on problem with old fuel.
Octane booster, Sta-Bil and fresh fuel finally cured my problems.

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