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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 12822
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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I have a Toro mower with a Briggs and Stratton engine model

Customer Question

I have a Toro mower with a Briggs and Stratton engine model 128M02 3456-B1. I have used this mower for 4 years with no problems. Today it refused to start. I installed a new Champion RJ18LMC plug and when I tried to start it it backfires.
Submitted: 5 months ago.
Category: Small Engine
Expert:  Peter Bagley replied 5 months ago.

Hello and welcome to just answer and allowing me to assist you. have you checked for a good blue crisp spark, and is there any contamination in the fuel?

Customer: replied 5 months ago.
There is excellent spark and no gas contamination
Expert:  Peter Bagley replied 5 months ago.

ok thank you for that info/ next you said it back fires right

Customer: replied 5 months ago.
It did it twice.
Expert:  Peter Bagley replied 5 months ago.

a couple of things that will do that is timing, lean mixture . so when you try to start it do you chock it or does this have an auto choke

Customer: replied 5 months ago.
Auto choke
Expert:  Peter Bagley replied 5 months ago.

so are you trying to start it cold first when it back fires?

Customer: replied 5 months ago.
I has to be cold since I haven't started it.
Expert:  Peter Bagley replied 5 months ago.

ok then not being there I suspect that the auto choke is not closing enough to rich en the fuel to initially start it properly . Can you access the choke plate and see if it's closed fully or open/

Customer: replied 5 months ago.
It's open. I have the air filter out of it to confirm that.
Expert:  Peter Bagley replied 5 months ago.

so the choke plate is open, that may very well be our problem

does it seem stuck or just no spring tension on the plate

Customer: replied 5 months ago.
The choke plate is closed and it wont start.
Customer: replied 5 months ago.
What now?
Expert:  Peter Bagley replied 5 months ago.

sorry had a glitch on the sight and didn't allow me to respond

Expert:  Peter Bagley replied 5 months ago.

ok try a few times to start with plate closed and then take out the spark plug and see if it is wet with fuel or dry

Customer: replied 5 months ago.
The spark plug is wet.
Customer: replied 5 months ago.
Where do we go from here?
Expert:  Peter Bagley replied 5 months ago.

something is not adding up here first you said the choke was open then it was closed and you have a good spark and fuel but not trying to start? The fuel is new or was it sitting for a long time?

Expert:  Peter Bagley replied 5 months ago.

ok remove the spark plug and burn it off with a lighter and while it's still warm put back in and try

Customer: replied 5 months ago.
The fuel was purchased last Tuesday. The choke plate was closed. Sorry for the confusion. That's what I can't understand. I have fuel and spark but it won't start.
Expert:  Peter Bagley replied 5 months ago.

ok lets do this step by step, good fuel getting to engine , good spark.how old is this unit?

Customer: replied 5 months ago.
I removed the plug and and used a lighter to burn off any excess fuel. Replaced the plug and it still won't start. The mower was purchased new by me 4 years ago. I mow a large yard and buy new gas every week. I bought a new plug this morning and gapped it at .020 per the manual.
Customer: replied 5 months ago.
I pulled the starter cord with the plug removed and gas came out of the plug hole.