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14.5 hp briggs & stratton backfire issue

#1

S

steveandjere

Hey everyone

I have a Simplicity mower with a Briggs and Stratton engine Model 28770 after engine is warm 5-10 Minutes starts to backfire from both carb and muffler. I have replaced the Carb, spark plug, cleaned the flywheel, rechecked all my gaps. Any ideas. Mower had been sitting for 2 years


#2

M

mechanic mark

Please post Simplicity model number, should be 7 numbers as well as all numbers from engine: model xxxxxx, type xxxx, trim xx.


#3

D

d29

Hello.

Your backfiring could be be caused by poor quality fuel which would explain the backfire out of the carburettor.
Alternatively it could also be the engine running to lean on the carburettor which would also cause this to happen.


#4

S

steveandjere

Its a Simplicity Riding Mower Model 1693911

Briggs And Stratton Engine Numbers 287707 0224-01 960815ZD


#5

S

steveandjere

Before I started it I did drain the old Fuel out and refueled it, installed a new fuel filter


#6

D

d29

Has the machine always done it or has it just started recently?


#7

D

dafoneguy

If it's been sitting for 2 years, you may have corrosion in the fuel solenoid. Remove the solenoid from the carburetor bowl and see if the plunger moves up and down. If it's stuck, clean it good with carb cleaner. Then test the solenoid by grounding it to the engine and touch the solenoid power wire to the positive battery terminal to make sure the plunger works. If it works, reinstall the solenoid and see if it still backfires. If the plunger doesn't move, you may have a bad solenoid.


#8

M

mglawnservice

If it turns out to not be a fuel problem you might look at the valves. A sticky valve can cause excessive back firing if not closing proper when the motor fires.


#9

Fish

Fish

What were the valves set at?


#10

S

steveandjere

Fish said:
What were the valves set at?
Click to expand...

Intake was at .004 exhaust was at .006


#11

S

steveandjere

dafoneguy said:
If it's been sitting for 2 years, you may have corrosion in the fuel solenoid. Remove the solenoid from the carburetor bowl and see if the plunger moves up and down. If it's stuck, clean it good with carb cleaner. Then test the solenoid by grounding it to the engine and touch the solenoid power wire to the positive battery terminal to make sure the plunger works. If it works, reinstall the solenoid and see if it still backfires. If the plunger doesn't move, you may have a bad solenoid.
Click to expand...

I replaced the Carb with a new one. wondering if there is a way to adjust it...


#12

S

steveandjere

d29 said:
Has the machine always done it or has it just started recently?
Click to expand...

Person we got it from had said it ran fine 2yrs ago


#13

M

mechanic mark

steveandjere said:
Its a Simplicity Riding Mower Model 1693911

Briggs And Stratton Engine Numbers 287707 0224-01 960815ZD
Click to expand...
Lawn Tractor Manuals | Riding Mower Manual | Simplicity Mowers

Results

Engine & Carburetor Backfire | Mower & Small Engine Repair | Briggs & Stratton FAQ


#14

pugaltitude

pugaltitude

The 287707 will be ohv.

Common thing on the ohv for engine farting and backfiring is the a blown head gasket.

It blows between the valve chamber and the cylinder.


#15

M

mglawnservice

Fish said:
What were the valves set at?
Click to expand...

Here is a link to the head assembly from Briggs,

http://www.briggsandstrattonpartstore.com/?gclid=CICp54Ta674CFcdFMgodQj8A1g#/Briggs_%26_Stratton/287707-0224-01/Head%2c_Valve_Gaskets%2c_Oil_Filter%2c_Dipstick/287707022401/27190003

Link to look up any group of parts for your motor
http://www.briggsandstrattonpartstore.com/?gclid=CICp54Ta674CFcdFMgodQj8A1g#/s/BRG/287707-0224-01//1

Not sure about the fly wheel key, in some models if a little play is present it can affect the timing


#16

S

steveandjere

UPDATE.. Mower running great it ended up being a sticky intake valve. replaced the head reset all gaps and it runs great. thanks for all the help everyone :wink:


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