Weber Carburetor Troubleshooting Guide

repair and adaptation of Weber carburetors. This guide is to help pinpoint problems by diagnosing engine symptoms associated with specific vehicle operating conditions.

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Test the fuel flow at the fuel filter and then at the Fuel Pump:
Check to see if the fuel tank is empty or if the lines are blockeThey maybe
If the vehicle is equipped with an electric fuel pump, test the pump by applying
Check to see if the fuel is old or ba( If vehicle has been out of service for an
Check to see if the fuel is contaminated with rust or water:
Test the fuel pressure output with a fuel pressure gaugIf the fuel pressure
See if the Fuel Return and the Fuel supply line are reverseOn some Weber
Make sure that none of the fuel lines are crimped or kinked.
Do a compression check on all of the cylinders. Compression should be over
See if the intake manifold bolts or loose or missing.
If you have a heated intakMake sure that the heat source is connected.
To make sure that you do not have any vacuum leaks, check all vacuum
Testing the vacuum system with a handheld vacuum pump is very helpful
Using the method of pinching off hoses is helpful when you have hoses that
Using Carburetor Cleaner to check for leaks. This will help you find defective
Testing the choke and the throttle linkage:
Testing the Idle Speed Adjustment:
Testing the Fast Idle Adjustment:
Testing the Automatic Choke adjustment.
Testing the choke thermostat assembly
Testing the idle cut-off solenoid (if equipped)
Testing the idle mixture adjustment:
Cleaning the idle circuit
Make sure that all of the vacuum lines are installed to the correct signal source.
Set the Float Level
Replace spark plugs; use only new spark plugs with the correct heat range.
Make sure that the ground strap is properly connecteIt is necessary that
Double check or have any work coincidental to the problem such as
Check for any damage to the exhaust system or an internally collapsed muffler.
Check your sparkplugs. Most Shop manuals have a chart in color showing
See if the Transmission is slippinThis applies to both automatic and standard.
Make sure that the fuel tank vent hose is not plugged at the canister.
Some Vehicles , including Nissans, have two wires that go to the electric choke.
Some original Electric Fuel pumps pressure exceeds 3.5 psCheck with a
On some water cooled VW\\\’s , vibrations caused by worn motor mounts may
When the throttle return spring is located on the same side as the throttle
On progressive carbs incorrect installation of the throttle lever can cause

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