Cold engine surging

F

Firespooks

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• Oct 11, 2025 / Cold engine surging

• #1

I have a 38” Husqvarna lawn tractor with a 18 1/2 HP B & S on it. When it is cold out side and I start it , the engine surges until it is warmed up. Then it runs smoothly. Is this normal ? Or should I be maintaining something ?

 

ILENGINE

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• Oct 11, 2025 / Cold engine surging

• #2

That is actually normal especially with the newer EPA mowers because they run too lean when they are cold.. I have seen several newer engines that won't even start below 50 degrees without outside assistance.

 

A

Auto Doc's

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• Oct 11, 2025 / Cold engine surging

• #3

Does it have a manual choke or automatic?

 

F

Firespooks

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• Oct 11, 2025 / Cold engine surging

• #4

Auto Doc's said:

Does it have a manual choke or automatic?

Click to expand...

Manual

 

S

slomo

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• Oct 11, 2025 / Cold engine surging

• #5

Firespooks said:

When it is cold out side and I start it

Click to expand...

What temp in F are you calling cold?

 

F

Firespooks

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• Oct 11, 2025 / Cold engine surging

• #6

Around 50 degrees.

 

Craftsman Garage

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• Oct 17, 2025 / Cold engine surging

• #7

Well, when you think about it, it actually makes sense, similar to what ILENGINE said. When air is cold, it is more dense, thus the engine actually pulls more air in with the same stroke. The fuel mixture stays the same whether cold or hot. So it runs lean for a little bit, but it's normal and nothing to worry about. If it has manual choke, you could pull the choke out more when running cold to even out the mixture.