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Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 22893
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Why does my gasoline engine continue to run for a few seconds

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Why does my gasoline engine continue to run for a few seconds after I switch off? It's a Kubota bought in the USA and running on European 95 octane (the lowest octane available here in the UK).

if its running on then its probably the ignition is too far retarded if you can tell me what model of tractor / lawn mower etc it is and I'll try to help further
Customer: replied 3 years ago.

Thanks, ***** ***** get it to you later today.


No problem
Customer: replied 3 years ago.

Hi Matt,

The ride-on mower with the running-on problem is a Kubota ZG 227 with gasoline engine. I bought it in the USA. Looking at the "soot" at the exhaust it seems to run rich. It's difficult to restart hot. Seems to be no adjustment possible at the carburettor (US regs?). And I assumed that the problem may lie with UK fuel having a higher octane than American. It's done 150 hours.

Over to you!
Hello Bob

you're right in saying the mixture adjustment is all sealed off
these engines don't run particularly clean in any case and the best way of checking the mixture strength is to remove the spark plug and check the colour of the deposits

see here for reference but it should be a light brown colour

Also there's a service manual available here

you have to pay for it though
Customer: replied 3 years ago.

Hello Matt,

Thanks again. I'll get the manual. You mentioned the ignition may be too far retarded and suggested, I think, that you might show me how to advance it. Could that be the answer? I have to say that you put my mind at rest when you said that these engines don't run particularly clean.



Hello Bob

there should be an ignition pickup that reads off the crankshaft which then is wired to the igniton coils

this pickup should have some adjustment on the mounting holes so its worth investigating if it can be moved slightly anti- clockwise to give more advance
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