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TROUBLESHOOTING FLOW CHARTS
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Bowl Style Carburetor Troubleshooting
Hunts and Surges Will Run only on Prime Will run only if the choke is used
Determine that the governor system is functioning properly using the proper isolation techniques
Does the engine still hunt and surge?
No
Troubleshoot governor system
Yes
Done!
Partially engage choke or gently touch primer bulb
No
Does the engine improve?
Yes
Inspect, clean or replace mainjet and retest
Does the engine still hunt and surge?
No
Remove and clean carburetor, retest engine
Does the engine still hunt and surge?
Yes
Yes
Replace Carburetor
No
Flow Chart Key Done! Problem
Question
Answer
Action
Result
Compression Diagnostics Troubleshooting Flow Chart Low Power
No
Check for proper top no load speed by model and type number
Is the top no load speed OK?
Check bowden wire/throttle control for full range travel
Low or High
Is it correct?
Yes
Yes
Is there a parasitic load?
Yes
No
Don’t Know
Disengage load by removing belts, etc.
No
Repair as needed
Still low power?
Repair load issues as needed
Partially engage choke
Yes
Is leakage detected?
Check for intake tract leaks, gasket leaks, loose/leaking carburetor space blocks, loose/leaking crossover tubes
Yes
Does speed increase or engine run more smoothly?
No
No Repair as needed
Perform leakdown test
Overhaul carburetor looking closely for obstructed jets
Is leakage detected?
Reading acceptable
Adjust valve lash Leakage unacceptable
Flow Chart Key
Repair as needed
Problem
Question
Answer
Action
Result
Compression Troubleshooting Flow Chart Engine Smokes
What color is the smoke?
White/Blue
Yes
Was engine tipped?
Check for oil fouled filter element
Is the filter fouled?
Check/repair fuel system
Black/Gray
Excessive Oil Consumption
Does oil level drop more than one ounce per hour?
Yes
Is Engine Smoking?
Yes
No
No
No
Oil use acceptable
Check for overfilled oil level Check for fuel contaminated oil Check for proper viscosity
No Leakage unacceptable
Rapair/replace faulty components
Is leakage detected?
Reading acceptable
Perform Crankcase Vacuum Test
Perform Leakdown Test
Yes
Is Vacuum Test OK?
Yes
Replace and run Engine for ten minutes
Is it still smoking?
Low No
Yes
External oil leaks present?
No
Re-check all work
Check breather system Check crankcase seals Check block for porosity
Yes Done!
Repair as needed
No
Is vacuum now ok?
Done!
Yes
Flow Chart Key
Problem
Question
Answer
Action
Result
Fuel System Troubleshooting Flow Chart Check for: Clean, fresh fuel supply, shutoff valve open, carb adjustments properly made, controls functioning
Engine Won’t Start/Run
All ok?
No
Correct and recheck
Yes
Check carburetor mounting gasket
Check spark plug
No
Is the spark plug wet?
Yes
Check for: Clogged air cleaner, stale fuel, oil/water in fuel, misadjusted controls, choke plate closed, damaged needle valve
Yes
Does the engine start/run?
No
Yes
Does the engine start/run?
Check fuel supply/passages
Check carburetor Put fuel in carburetor
Put fuel in spark plug hole
Done!
No
Yes
Does the engine start/run? No
Does it have a Flo-jet Carburetor?
No What kind of carburetor?
Flo-jet Carburetor
Check for: Clogged fuel line/filter, fuel inlet valve closed, improper float level, carburetor fuel passages plugged/restricted, faulty fuel pump
Yes
Diaphragm Carburetor
Recheck other work
Check Compression
Check for: Inlet valve stuck open, improper float level, dirt in the carburetor, loose nozzle(s)
Check for: Gummy/dirty inlet screen, valve stuck, bad diaphragm, restricted passages in tank/carburetor
Done! Done!
Done!
Flow Chart Key
Problem
Question
Answer
Action
Result
Systematic Troubleshooting Electrical System Flow Chart
Engine Won’t Start
Check for spark to ground.
Check spark plug/replace if necessary. Try to start engine.
OK
None
Will engine start?
Check armature air gap.
Incorrect
No
OK
Adjust armature air gap
Check/replace flywheel key
Yes
Will engine start?
Will engine start?
Done!
No
No
Yes
Done!
Yes
Done!
Isolate engine from equipment Check fuel system
Check for spark to ground.
Check compression system
Check coil to block ground.
None
OK
None
OK Fix
Check for misadjusted controls
Check interlock switching
Replace Coil
Check grounding wire diode (if equipped)
Flow Chart Key
Problem
Question
Answer
Action
Result
Governor Troubleshooting Flow Chart Air Vane Governor – Overspeeding
Done! Air Vane Governor – Overspeeding
No Check the cooling system
Is the cooling system ok?
Remove dirt and debris from outside and inside of blower housing, test engine
No
Still overspeeding?
Done!
Yes Yes
No
Check flywheel fins
Are the flywheel fins ok?
Replace flywheel if fins are missing or broken, test engine
No
Still overspeeding?
Yes Done!
Yes
Check for uneven or binding resistance in air vane travel from stop to stop
Resistance problem?
No
Indentify resistance and repair, test engine
Yes
Still overspeeding?
No Yes
Inspect governor spring and controls for damage or improper installation
Replace governor spring or controls, test engine
Done! Flow Chart Key
Problem
Question
Answer
Action
Result
Governor Troubleshooting Flow Chart Air Vane Governor – Engine Runs Too Slow
Air Vane Governor – Engine Runs Too Slow
Done!
Move trottle control to idle, check for binding or uneven resistance in air vane travel from stop to stop
No
Resistance problem?
Indentify resistance and repair, re-test engine
Yes
Engine still runs too slow?
No Yes
Inspect governor spring and controls for damage or improper installation
Replace governor spring or controls, re-test engine
Done!
Flow Chart Key
Problem
Question
Answer
Action
Result
Governor Troubleshooting Flow Chart Hunting and Surging
Hunting and Surging
Adjust carburetor idle speed, idle fuel, and top no load fuel, test engine
No
Still hunting and surging?
Done!
Yes
Perform static governor adjustment procedure, test engine
Still hunting and surging?
Done!
No
Yes
Done!
Inspect governor link spring for damage or improper installation
No
Link spring need repair or replacement?
Repair or replace link spring as needed, test engine
Yes
Still hunting and surging?
No Done!
Yes
Disconnect governor spring, check for binding or uneven resistance in governor arm travel from stop to stop
Resistance problem?
No
Indentify resistance and repair, test engine
Yes
Still hunting and surging?
No Yes
Inspect governor spring and controls for damage or improper installation
Flow Chart Key Replace governor spring or controls, test engine
Done! Problem
Question
Answer
Action
Result
Governor Troubleshooting Flow Chart Mechanical Governor – Engine Runs Too Slow
Mechanical Governor – Engine Runs Too Slow
Perform the static governor adjustment procedure, test engine
Engine still runs too slow?
No
Done!
No
Done!
Yes
Adjust governor spring tension, test engine
Engine still runs too slow?
Yes Done!
Disconnect governor spring, check for binding or uneven resistance in governor arm travel from stop to stop
Resistance problem?
No
Indentify resistance and repair, test engine
Yes
Engine still runs too slow?
No Yes
Inspect governor spring and controls for damage or improper installation
Replace governor spring or controls, test engine
Done! Flow Chart Key
Problem
Question
Answer
Action
Result
Governor Troubleshooting Flow Chart Mechanical Governor Engine Overspeeds
Mechanical Governor Engine Overspeeds
Still overspeeding?
Perform the static governor adjustment procedure, test engine
Still overspeeding?
No
Adjust governor spring tension, test engine
Yes
Done!
Done!
No
Yes Done!
Disconnect governor spring, check for binding or uneven resistance in governor arm travel from stop to stop
Resistance problem?
No
Indentify resistance and repair, test engine
Yes
Still overspeeding?
No
Done! Yes
Move throttle plate to the wide open position and start engine
Does engine return to idle?
No
Remove crankcase cover or sump and inspect or replace internal governor mechanism, test engine
No
Still overspeeding?
Yes Yes
Inspect governor spring and controls for damage or improper installation
Replace governor spring or controls, test engine
Flow Chart Key Done!
Problem
Question
Answer
Action
Result
Compression System Troubleshooting Flow Chart Leakdown Test
Perform Leakdown Test
Reading acceptable
Is leakdown test ok?
Recheck other work
Leakage unacceptable
Where is the air primarily leaking from?
Muffler
Dipstick Tube
Air Cleaner
Cylinder Head
Reset exhaust valve
Check rings
Reset intake valve
Check head gasket
Flow Chart Key
Problem
Question
Answer
Action
Result
Gaseous Fueled Engine Troubleshooting Frost forming on the regulator or on the fuel line – liquid (not vapor) entering the system.
Engine does not accelerate from low speed to high speed or run smoothly when loaded.
Plugged vent ports on the regulator.
Less than 11 inches of water pressure at the inlet of the secondary regulator.
Remove plastic shipping plugs.
Adjust the output of the primary regulator to 11 inches of water pressure. If natural gas supply is lower than 11 inches of water, a different secondary regulator may be required – consult factory.
Wrong type of propane tank – set up for liquid withdrawal.
Tank is positioned wrong (typically tanks that lay on their side).
Fuel tank is overfilled. More than 14 inches of water pressure at the inlet of the secondary regulator at full load.
Plugged fuel filter.
Kinked or obstructed fuel hose.
No or low fuel in tank.
Propane tank is too small.
Fuel transfer solenoid in the wrong position.
Adjust the primary regulator to achieve 11 inches of water pressure while under load. Note: if pressure at inlet of secondary regulator increases upon starting the engine, check primary regulator for holes or tears in the diaphragm or dirt on the inlet seat.
Replace fuel filter.
Fuel tank is too small, especially if the ambient is low.
Restriction within the fuel line.
Fuel tanks have a receptacle for a locator pin that orients the tank for a specific withdrawal. Pin may be in the wrong location or missing. Reposition tank.
Fill to labeled tank capacity only.
Increase the size of the fuel tank to increase the vaporization rate of the fuel. Consult with local gas supplier.
Remove restriction or replace damaged part.
Remove the kink and/or replace the hose.
Refuel the tank.
Appropriately size the fuel tank for the engine horsepower and lowest ambient temperature.
When the fuel solenoid is energized or if the main mixture adjustment screw is completely seated, the engine is configured for propane gas (too lean of a mixture for natural gas). If the fuel solenoid is not energized, the engine is configured for natural gas (too rich mixture with propane).
Gas will not stop flowing after engine is stopped.
Regulator is not adjusted properly.
Atmospheric side of the secondary regulator is pressurized.
Debris on inlet needle of secondary regulator. Carburetor not adjusted properly (natural gas only).
Readjust the mixture needles on the carburetor.
Air leak in the fuel line from secondary to carburetor.
Tighten the clamps or replace the hose.
Holes, tears or damaged diaphragm in secondary regulator.
Replace the fuel tank or change to the vapor withdrawal port.
Regulator not positioned vertically.
Adjust the regulator so that when the outlet tube is placed in water, a gas bubble just begins to form. Back off on the adjustment so that the bubble is maintained but does not grow.
Remove plastic shipping plugs or revise the regulator venting.
Clean the system of debris and install a fuel filter. Use liquid pipe sealant – do not use Teflon tape.
Regulator may only be positioned with the outlet pointing straight up. A directional arrow is also shown on the smooth side of the regulator.
Replace damaged part. Gas leak from fuel line.
Debris on inlet needle of regulator.
Clean system of debris and add a fuel filter. Use liquid pipe sealant – do not use Teflon tape. Loose fitting.
Damaged, cracked or worn hose.
Engine will not start.
Out of fuel.
Tighten fitting – replace if damaged.
Replace hose.
Refuel the tank. Gas leak from regulator.
Fuel supply shut off.
Filter or vacuum lock off is not opening.
Vacuum leak in the vacuum lock off device.
Filter is plugged.
Open fuel tank.
Check for proper operation of all fuel lock off (safety) devices. If electrically actuated, check for dead battery or blown fuse. Replace lock off device if it is not functioning properly
Damaged diaphragm in regulator.
Replace vacuum line or tighten clamps. Replace vacuum lock off if damaged.
Replace filter.
Replace damaged part.
Flow Chart Key
Symptom
Potential Cause
Action
Briggs&Stratton corporation
CE8117-09/08
Customer Education PO BOX 702 Milwaukee, WI 53201 USA 414 259 5333
