Engine won't start
Insufficient fuel level in the float chamber. Check fuel pump supply. Also check the needle valve for patency and signs of jamming.
Spark plugs from a cold engine are full of fuel due to over-hard work on the accelerator during starting. Keep the pedal released and repeat the starting procedure until the engine starts.
Spark plugs of a hot engine are flooded with excessive use of the gas pedal. Keep the pedal released until the engine starts. Make sure the automatic start choke is fully open.
Note. On models equipped with a sight glass on the carburetor float chamber, visually check the fuel level in the chamber.
On models without a viewing window, move the throttle lever while observing fuel injection into the primary chamber of the carburetor.
Check for fuel supply problems by disconnecting the fuel supply line from the carburetor and then cranking the engine. The engine bay is indicated by a strong smell of gasoline and the presence of traces of fuel leaks along the axes of the throttle valves.
Note. See also the checks described in the Checking the power system section of the Section Diagnostics of failures when starting the engine on the road.
Engine stalls when idling
The setting of the speed and / or the quality of the idle mixture is violated. Check and, if necessary, correct the settings with the adjusting screws.
Faulty starter unit. Check choke function and fast idle speed adjustment.
Carburetor float chamber filled. If possible, check the fuel level in the chamber through the viewing window. Clean and blow out the carburetor.
The patency of the idle jet or air jet is broken. Clean and blow out the carburetor.
The bolts securing the carburetor to the intake manifold have loosened. Tighten the bolts and check for air leaks.
There are leaks from the carburetor flange gaskets or the intake manifold. Check and replace defective gaskets. Leaks through the intake manifold gasket can be detected by wetting the suspect joint with engine oil (see accompanying illustration).
Defective fuel cut off solenoid valve. Check the function of the valve, make the necessary repair or replacement.
Insufficient fuel supply to the carburetor. Check for proper fuel flow through the needle valve. Clean and blow out the carburetor. Check the patency of the fuel lines and the fuel filter, as well as the proper functioning of the fuel pump.
Decreased vehicle handling
Faulty or blocked accelerator pump. Clean and blow out the carburetor, replace defective components.
The accelerator pump drive rod is faulty. Check and make necessary repairs.
Faulty automatic start unit. Check the function of the air damper.
Note. To check the accelerator pump circuit, remove the air cleaner and, while holding the choke open, manually move the throttle control lever. A stream of fuel injected into it should be visible through the neck of the carburetor.
There are misfires
Note. Before performing the checks and corrections described below, perform diagnostics of electrical equipment.
The fuel level in the carburetor float chamber has dropped, or the fuel supply to the carburetor is disrupted. Check the level, serviceability of the fuel pump and the patency of the fuel lines and fuel filter.
There is a blockage in the main or high power jet. Disassemble the carburetor, blow out the jets.
Fuel pump defective. Replace.
Water has entered the carburetor. Dry and clean the power system, replace the fuel filter.
There is air suction between the fuel pump and the tank. Eliminate leaks.
Note. Check supply pressure (pressure) and flow rate of the fuel pump, as described in the relevant Section.
Remove the top cover to check for moisture in the carburetor. The procedures for removing the disassembly of the carburetor are described in detail in Chapter Power supply and exhaust systems.
Excessive fuel consumption
The fuel level in the float chamber is too high. Check, make adjustments.
The air cleaner element is dirty. Make a replacement.
The air damper is partially closed. Check and make any necessary corrections.
Fuel pump pressure too high. Replace pump.
There are leaks from the fuel tank, fuel lines or through the filter. Check and make any necessary replacements.
Worn or damaged jets. Check and replace defective components.
Excessive load on the accelerator pump. Change your driving style.
Note. In most cases, excessive fuel consumption is associated with a violation of the air cleaner filter element, which is easily removed and visually inspected. You should also check the settings and the correct functioning of the automatic start.
Fuel injection and engine management systems
(late 4.2 liter models)
Note. The checks below are categorized as basic only. In addition, their implementation should be started only after the results of the procedures listed in the Sections on diagnosing the causes of failure to start the engine on the road allow you to firmly state that the problem is related to malfunctions of the fuel injection and engine control systems.
If the checks described below do not give a positive result, you should seek help from the specialists of the dealership of the car manufacturer, who have at their disposal special and very expensive diagnostic equipment.
Warning! Exercise extreme caution when performing repair or diagnostic procedures on or near electronic ignition system components to avoid serious electrical shock injury. Be aware that there is a high voltage hazardous to health in the secondary circuit of the system
Engine does not start or starts with great difficulty
Faulty ignition system. Check the external condition of the contact terminals of the distributor, the ignition coil and the powerful key of the output stage. Terminals must be clean, free from corrosion products and securely fastened. Check the condition of the spark plugs and the setting of the electrode gaps. Check the distributor cover and slider for cracks, carbon tracks, burnt terminals (see accompanying illustration). Check the condition of the terminals of the BB wires, measure their resistive resistance. Check the condition of the ignition coil and output stage power key.
Fuel supply interrupted. Check fuel pump, fuel pump relay and fuel pressure.
Faulty injectors. Check the electrical circuit of the injectors. Check the condition of the fuse links.
Faulty control relay (ECCS relay). Check relay, replace if necessary.
The electrical connectors of the components of the engine management system are faulty. Check the condition of all electrical connectors, clean the terminals, monitor the reliability of the connections.
Engine starts, then stalls
The setting of the idle speed or ignition timing is violated. Check and make any necessary adjustments.
Fuel supply interrupted. Check fuel pump electrical circuit and fuel pressure.
Faulty ignition system. Check up a condition of spark plugs and correctness of installation of an interelectrode gap. Check the distributor cap and slider for cracks and carbon tracks. Check the condition of the terminals of the BB wires, measure their resistive resistance. Check the condition of all other terminal connections of the ignition system.
There are air leaks or vacuum losses. Check up a condition and reliability of fastening on fittings of corresponding hoses.
The electrical wiring of the fuel management system components is faulty. Check the condition and security of all terminal connections.
There are engine misfires
Spark plugs are defective or dirty, or the electrode gap is incorrectly set.
Defective distributor cap. Check the lid for cracks and moisture.
Faulty BB wires. Check and make any necessary replacements.
Faulty ignition coil. Check and replace if necessary.
Fuel supply interrupted. Check fuel pressure. Check the fuel filter, lines and injectors for leaks.
Moisture has entered the fuel. Drain fuel, replace fuel filter.
Faulty fuel injectors. Check up a condition of electric sockets and an electric chain of injectors.
The engine does not develop full power
The filter element of the air cleaner is clogged or the patency of the air intake path is impaired. Replace element (see accompanying illustration), or remove the cause of the blockage.
Throttle cable adjustment is broken. Make the necessary adjustments, make sure that the damper opens completely.
The setting of the ignition timing is violated. Check, correct.
Fuel supply interrupted. Check fuel pressure. Check the patency of the fuel filter, lines and injectors. Make sure the fuel pressure regulator vacuum hoses are connected and in good condition.
The patency of the exhaust gas system is broken. Check the state of the system, eliminate the cause of the blockage.
Excessive fuel consumption
The filter element of the air cleaner is clogged or the patency of the air intake path is impaired. Replace the element, or eliminate the cause of the blockage.
Fuel pressure not correct. Measure the pressure. Check the continuity of the fuel return line.
There are external leaks in the fuel supply system. Check for signs of leaks at the fittings and components of the power system.
There are internal leaks in the fuel supply system. Check injectors for signs of leaks.
The patency of the exhaust gas system is broken. Check the state of the system, eliminate the cause of the blockage.