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JohnF2015, Small Engine Technician
Category: Small Engine
Satisfied Customers: 1102
Experience:  Owner/Service Technician at S & J Small Engines
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I have a Briggs & Stratton Quantum 675 series engine on a

Customer Question

I have a Briggs & Stratton Quantum 675 series engine on a Snapper model SPV 22675HW (7800190) push mower. I changed its oil, got a new spark plug and cleaned the air filter. It starts right up when I pull the cord, but then goes "VROOM chug-a, chug-a, VROOM, " etc. After a couple of minutes it runs more smoothly, but I don't think it's at full power. I've tried to put in only enough gas for each mowing, so I don't think it's stale gas.
Submitted: 1 year ago.
Category: Small Engine
Expert:  JohnF2015 replied 1 year ago.

Hi, my name is***** will be assisting you.

Did you by chance turn the mower on its side when changing the oil?

Customer: replied 1 year ago.
No, never. The owner's manual warns against this. I raised the front of the mower, loosened the bolt beneath and let the oil drain into a pan.
Expert:  JohnF2015 replied 1 year ago.

Remove the air filter and start the machine and see if makes any difference. I would not mow with it this way but just to check it.

Customer: replied 1 year ago.
Tried that but still doesn't work
Expert:  JohnF2015 replied 1 year ago.

Then the next suggestion that I have is to clean the carburetor thoroughly. It sounds like there is something that has made its way into the carburetor and is blocking or partially blocking the jets which is not allowing enough fuel to pass through to keep the engine running at a steady or constant rpm.

Customer: replied 1 year ago.
You can communicate much faster than I can--I access the internet at the public library during hours when it's open, and last week we had a string of rainy days during which I couldn't take the lawn mower out (I never have, anyway). When I removed the air filter the engine started just as before: "VROOM, chug-a, chug-a, VROOM," etc. It made no difference. I'll check the owners manual for the carboretor. I've never seen it. The Quantum engine has a cover over the engine components. Might there be some sort of an additive I could add that might clear the obstruction?
Expert:  JohnF2015 replied 1 year ago.

You could add a carburetor cleaning agent similar to SeaFoam but the machine will then need to run for possibly and hour if not longer for it to do any good. The carburetor is right behind the air filter base or assembly.

Customer: replied 1 year ago.
I seem to have gotten behind: you had said the problem might be in the carburetor, and I said I'd look for information in the Briggs & Stratton Quantum 675 series owner's manual. There the key to the illustrated engine components doesn't list any carburetor. Later in the manual there's a somewhat contradictory paragraph: "
CARBURETOR ADJUSTMENT. Never make adjustments to the carburetor. The carburetor was set at the factory to operate efficiently under most conditions. However, if adjustments are required, see any Briggs & Stratton authorized dealer for service." That was why I asked my question in the first place: There aren't any dealers nearby. Thank you, Peter
Expert:  JohnF2015 replied 1 year ago.

There are no adjustments that can be made on this carburetor. It is fixed jetting and can't be adjusted due to EPA emission regulations. It could however have something partially blocking the jets that would cause this symptom or issue.

I am including a picture of the carburetor with this comment or post so that you might get a better idea of what you are looking for. The reference that I have made to cleaning the jets would be to look at the diagram and pick out the bowl nut that holds the carburetor bowl on (reference # *****), this has three holes in it that serve as the main jets for the carburetor if any one of them becomes blocked or even partially blocked it can cause the machine to run the way that you are describing.

Customer: replied 1 year ago.
Dear *****F2015,
You mentioned a "carburetor cleaning agent" such as Seafoam; is one agent preferable to another? Running the machine for an hour wouldn't be a problem, I'll tie down the bail. Perhaps that would be better than trying to clean it, since I'm not a skilled mechanic. I made a print of your diagram, however, in case I'll need it.
Expert:  JohnF2015 replied 1 year ago.

No, there is really not one preferred over another. I just know that in my area everyone talks about how good SeaFoam is, myself I don't really believe that it does what the company says that it will but everyone has their opinions.

Thank you it has been a pleasure to assist you.

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