TROUBLESHOOTING FLOW CHARTS
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? Troubleshoot governor system Partially engage choke or gently touch primer bulb Does the engine improve? Inspect, clean or replace mainjet and retest Does the engine still hunt and surge? Remove and clean carburetor, retest engine Does the engine still hunt and surge? Replace Carburetor
Compression Diagnostics Troubleshooting Flow Chart Low Power Check for proper top no load speed by model and type number Is the top no load speed OK? Is there a parasitic load? Check bowden wire/throttle control for full range travel Low or High Yes Don t Know Is it correct? Disengage load by removing belts, etc. Repair as needed Still low power? Repair load issues as needed Partially engage choke Is leakage detected? Check for intake tract leaks, gasket leaks, loose/leaking carburetor space blocks, loose/leaking crossover tubes Does speed increase or engine run more smoothly? Repair as needed Perform leakdown test Overhaul carburetor looking closely for obstructed jets Is leakage detected? Reading acceptable Adjust valve lash Leakage unacceptable Repair as needed
Compression Troubleshooting Flow Chart Engine Smokes What color is the smoke? Black/Gray Check/repair fuel system Excessive Oil Consumption White/Blue Is Engine Smoking? Does oil level drop more than one ounce per hour? Was engine tipped? Check for oil fouled filter element Check for overfilled oil level Check for fuel contaminated oil Check for proper viscosity Oil use acceptable Is the filter fouled? Leakage unacceptable Rapair/replace faulty components Replace and run Engine for ten minutes Is leakage detected? Reading acceptable Perform Crankcase Vacuum Test Is it still smoking? Perform Leakdown Test Is Vacuum Test OK? Low External oil leaks present? Re-check all work Check breather system Check crankcase seals Check block for porosity Repair as needed Is vacuum now ok?
Fuel System Troubleshooting Flow Chart Engine Won t Start/Run Check for: Clean, fresh fuel supply, shutoff valve open, carb adjustments properly made, controls functioning All ok? Correct and recheck Check carburetor mounting gasket Check spark plug Is the spark plug wet? Check for: Clogged air cleaner, stale fuel, oil/water in fuel, misadjusted controls, choke plate closed, damaged needle valve Does the engine start/run? Does the engine start/run? Check fuel supply/passages Check carburetor Put fuel in carburetor Put fuel in spark plug hole Does the engine start/run? Does it have a Flo-jet Carburetor? What kind of carburetor? Diaphragm Carburetor Recheck other work Flo-jet Carburetor Check for: Gummy/dirty inlet screen, valve stuck, bad diaphragm, restricted passages in tank/carburetor Check Compression Check for: Inlet valve stuck open, improper float level, dirt in the carburetor, loose nozzle(s) Check for: Clogged fuel line/filter, fuel inlet valve closed, improper float level, carburetor fuel passages plugged/restricted, faulty fuel pump
Systematic Troubleshooting Electrical System Flow Chart Engine Won t Start Check for spark to ground. OK Check spark plug/replace if necessary. Try to start engine. ne Will engine start? Check armature air gap. Incorrect OK Adjust armature air gap Check/replace flywheel key Will engine start? Will engine start? Isolate engine from equipment Check fuel system Check compression system Check for spark to ground. ne Check coil to block ground. ne OK OK Fix Check for misadjusted controls Check interlock switching Check grounding wire diode (if equipped) Replace Coil
Governor Troubleshooting Flow Chart Air Vane Governor Overspeeding Air Vane Governor Overspeeding Check the cooling system Is the cooling system ok? Remove dirt and debris from outside and inside of blower housing, test engine Still overspeeding? Check flywheel fins Are the flywheel fins ok? Replace flywheel if fins are missing or broken, test engine Still overspeeding? Check for uneven or binding resistance in air vane travel from stop to stop Resistance problem? Indentify resistance and repair, test engine Still overspeeding? Inspect governor spring and controls for damage or improper installation Replace governor spring or controls, test engine
Governor Troubleshooting Flow Chart Air Vane Governor Engine Runs Too Slow Air Vane Governor Engine Runs Too Slow Move trottle control to idle, check for binding or uneven resistance in air vane travel from stop to stop Resistance problem? Indentify resistance and repair, re-test engine Engine still runs too slow? Inspect governor spring and controls for damage or improper installation Replace governor spring or controls, re-test engine
Governor Troubleshooting Flow Chart Hunting and Surging Hunting and Surging Adjust carburetor idle speed, idle fuel, and top no load fuel, test engine Still hunting and surging? Perform static governor adjustment procedure, test engine Still hunting and surging? Inspect governor link spring for damage or improper installation Link spring need repair or replacement? Repair or replace link spring as needed, test engine Still hunting and surging? Disconnect governor spring, check for binding or uneven resistance in governor arm travel from stop to stop Resistance problem? Indentify resistance and repair, test engine Still hunting and surging? Inspect governor spring and controls for damage or improper installation Replace governor spring or controls, test engine
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? Adjust governor spring tension, test engine Engine still runs too slow? Disconnect governor spring, check for binding or uneven resistance in governor arm travel from stop to stop Resistance problem? Indentify resistance and repair, test engine Engine still runs too slow? Inspect governor spring and controls for damage or improper installation Replace governor spring or controls, test engine
Governor Troubleshooting Flow Chart Mechanical Governor Engine Overspeeds Mechanical Governor Engine Overspeeds Perform the static governor adjustment procedure, test engine Still overspeeding? Adjust governor spring tension, test engine Still overspeeding? Disconnect governor spring, check for binding or uneven resistance in governor arm travel from stop to stop Resistance problem? Indentify resistance and repair, test engine Still overspeeding? Move throttle plate to the wide open position and start engine Does engine return to idle? Remove crankcase cover or sump and inspect or replace internal governor mechanism, test engine Still overspeeding? Inspect governor spring and controls for damage or improper installation Replace governor spring or controls, test engine
Compression System Troubleshooting Flow Chart Leakdown Test Perform Leakdown Test Is leakdown test ok? Reading acceptable 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
Gaseous Fueled Engine Troubleshooting Engine does not accelerate from low speed to high speed or run smoothly when loaded. Frost forming on the regulator or on the fuel line liquid (not vapor) entering the system. Plugged vent ports on the regulator. Remove plastic shipping plugs. Wrong type of propane tank set up for liquid withdrawal. Replace the fuel tank or change to the vapor withdrawal port. Less than 11 inches of water pressure at the inlet of the secondary regulator. 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. Tank is positioned wrong (typically tanks that lay on their side). 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. More than 14 inches of water pressure at the inlet of the secondary regulator at full load. Adjust the primary regulator to achieve 11 inches of water pressure while under load. te: 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. Fuel tank is overfilled. Fuel tank is too small, especially if the ambient is low. 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. Plugged fuel filter. Replace fuel filter. Restriction within the fuel line. Remove restriction or replace damaged part. Kinked or obstructed fuel hose. Remove the kink and/or replace the hose. or low fuel in tank. Refuel the tank. Gas will not stop flowing after engine is stopped. Propane tank is too small. Appropriately size the fuel tank for the engine horsepower and lowest ambient temperature. Regulator is not adjusted properly. 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. Fuel transfer solenoid in the wrong position. 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). Atmospheric side of the secondary regulator is pressurized. Remove plastic shipping plugs or revise the regulator venting. Carburetor not adjusted properly (natural gas only). Readjust the mixture needles on the carburetor. Debris on inlet needle of secondary regulator. Clean the system of debris and install a fuel filter. Use liquid pipe sealant do not use Teflon tape. Air leak in the fuel line from secondary to carburetor. Tighten the clamps or replace the hose. Regulator not positioned vertically. Regulator may only be positioned with the outlet pointing straight up. A directional arrow is also shown on the smooth side of the regulator. Holes, tears or damaged diaphragm in secondary 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. Tighten fitting replace if damaged. Engine will not start. Damaged, cracked or worn hose. Replace hose. Out of fuel. Refuel the tank. Gas leak from regulator. Fuel supply shut off. Open fuel tank. Filter or vacuum lock off is not opening. 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 damaged part. Vacuum leak in the vacuum lock off device. Replace vacuum line or tighten clamps. Replace vacuum lock off if damaged. Filter is plugged. Replace filter. Symptom Potential Cause
CE8117-09/08 Briggs&Stratton corporation Customer Education PO BOX 702 Milwaukee, WI 53201 USA 414 259 5333