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Lawnmower engine issue (B&S 5.5 hp)

Posted by marknmt 5b (My Page) on
Wed, Mar 27, 13 at 20:28

We were given a reasonably new Husqvarna mower with a B&S 5.5 hp Diamond Power 4 cycle engine. The previous owner had overfilled the crankcase, but after draining the engine, cleaning the spark plug and adding new gas (with a touch of Seafoam added) the engine starts and runs.

But there is a noticeable miss as it runs. I still need to replace the air filter, and that may help, but is there anything else I can do to smooth it out?

I really don't think the machine has been used that much; it's kind of a heavy clunker and we may not keep it, but it would be nice to have it in good condition if we find somebody we could give it to.



Follow-Up Postings:

RE: Lawnmower engine issue (B&S 5.5 hp)

Engine MODEL & TYPE numbers allow one to identify which specific engine it is. That helps to identify which carb is used.

IF the air cleaner was saturated with oil, replace it.
I'd invest in a new spark plug. That may not be the problem, but for a couple $, you can eliminate it as a potential cause.

Most of these newer engines are jetted too lean to meet EPA specs. Any gum/varnish in the main jet will reduce its size further, leaning out the mix more. This tends to result in SURGING.

Do you have a surge or a miss?

RE: Lawnmower engine issue (B&S 5.5 hp)

I do have a miss. The spark plug was fouled but otherwise good; I cleaned it thoroughly but don't mind replacing it when I get the new filter.

Will the Seafoam help clean the jets?

Sorry to say I have been unable to locate the model number. I'll post back after I get a chance to take the cowling off.

Thanks for responding.

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