Carb Troubleshooting

Carburetor Troubleshooting Guide

 

 

Problem Solution
Overflow of Fuel see solution
Shortage of Fuel flow see solution
Poor idling or stalling see solution
Poor running at low speed (under 1/4 throttle opening) see solution
Poor running at intermediate speed (just above 1/4 throttle opening); hesitation see solution
Poor running at medium speed (1/4-3/4 throttle opening) see solution
Poor running at high speed (1/2 throttle opening) see solution
Hesitation; runs worse when warm see solution
Fuel consumption see solution
Operation of throttle and cable are stiff  see solution
Operation of enrichener see solution
Hard starting (cold engine) see solution
Hard starting (warm engine) see solution

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Overflow of Fuel   top

Clogged Needle Valve

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Disassemble and Clean

Clogged Air Vent

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Clean Air Vent Passage

Abrasion of Needle

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Replace

Excessive Raised Fuel Level

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Replace Valve Seat With Smaller Inlet Diameter

Pressurized Fuel Tank

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Check Vent System on Tank
Shortage of Fuel Flow   top
Check Gasoline Supply

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Refuel
Closed Fuel Valve

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Turn Valve On
Fuel Inlet is not Hooked up Correctly

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Check Fuel Inlet
Needle Valve Clip is not Assembled

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Correctly Assemble
Shortage of Fuel Inlet

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Replace Fuel Fitting
Poor Idling of Stalling   top
Incorrect Adjustment of Pilot Screw

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Adjust
Idle Speed Adjusted Too Low

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Raise Idle Speed
Incorrect Adjustment of Air Screw

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Adjust
Air Leakage From Starter Plunger

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Adjust Starter Level and Plunger Movement
Air Leakage From Adapter

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Tighten Mount Adapter
Clogged Slow Jet

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Disassemble and Clean
Incorrect Slow System Calibration

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Select Slow Jet and Slow Air
 

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Adjust Air Screw
Throttle Shaft and Linkage Sticking

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Clean and Inspect; Lubricate
Incorrect Synchronized Throttle Valves

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Synchronize Throttle Valves
Poor Running at Low Speed (Under 1/4 Throttle Opening)   top
Poor

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Select Correct Jet
Too Lean; No Power

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Larger Size Slow Jet
 

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Use Richer Jet Needle (Larger Straight Diameter)
Too Rich

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Use Smaller Jet Size
Runs Better Without Air Cleaner

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Use Leaner Jet Size
 

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Throttle Valve With A Larger Cutaway
Poor Running at Intermediate Speed (Just Above 1/4 Throttle Opening); Hesitation   top
Clogged Main Jet

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Disassemble and Clean
Calibration Too Lean

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Raise Jet Needle By Lowering Clip
 

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Use Needle Jet With Higher Protrusion
 

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Use Needle Jet With Larger Recess Diameter
Too Lean

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Lower Jet Needle By Raising Clip
 

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Use Needle Jet With Lower Protrusion
 

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Use Needle Jet With Smaller Recess Diameter
Poor Running at Medium Speed (1/4-3/4 Throttle Opening)   top
Too Lean

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Use Richer Jet Needle
 

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Replace Air Funnel For A Longer One
Clogged Air Vent

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Cleaning Required
Poor Running at High Speed (1/2 Throttle Opening)   top
Too Lean

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Use Larger Main Jet
 

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Use Richer Jet Needle
 

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Replace Air Funnel For A Longer One
Clogged Air Vent

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Cleaning Required
Hesitation, Runs Worse When Warm   top

Too Rich

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Use Smaller Main Jet
Fuel Consumption   top
Carb Bore Too Large

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Replace With Smaller Bore
Starter Plunger Seal

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Replace Seal
Calibration

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Use Screen Type Needle Jet
 

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Lower Jet Needle By Raising Clip
 

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Use Smaller Tapered Jet Needle
Operation of Throttle and Cable are Stiff   top
(Maul Tech can cut your spring on any stiff Carburetor to your liking)
Wire Cable Twisted or Pinched

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Eliminate Problem
Tensioned Inner Wire of Cable

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Adjust Proper Play of Inner Wire
Damaged Bearing

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Replace
Dusty Bearing, Dusty Throttle Valve

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Disassemble and Clean or Replace and Lubricate
Dusty Throttle Valve

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Disassemble and Clean or Replace
Rubber Seal of Throttle Shaft

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Replace
Return Spring Force Too Strong

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Use Softer Spring
 

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Shift Position of Spring (CR's Only)
Damaged Floating Valve

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Replace
Stiff Only at Wide Open Throttle

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Adjust Clearance Between Body and Linkarm
Operation of Enrichener   top
Warped Starter Level

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Replace
Clogged

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Disassemble and Clean
Hard Starting (Cold Engine)   top
Clogged Pilot Jet  ---------- Clean Pilot Jet
Lean Starter System

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Replace Starter Jet With Larger Size
Worn out Intake Valves

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Replace with new valves
Incorrect Valve Lash

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Adjust Valves to Specifications
Lean Mixture Due to Open Throttle Valve

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Adjust Throttle Opening or Idle Screw
Hard Starting (Warm Engine)   top
Over Use of Throttle While Engine is Warm

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Stop Pumping the Throttle When Starting
Over Rich Starter System

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Replace the Starter Jet With Smaller One
Shortage of Air Intake

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Adjust Throttle Valve Opening or Idle Screw
Valves are too loose

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Adjust Valves to specifications
Flooded Engine

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Hold Throttle Wide Open and Kick Engine Over 10 Times