TESTING

Belt Tension and Air Leaks

1. Before proceeding with the tests, check the pump drive belt tension to see if it is within specifications.
2. Turn the pump by hand. If it has seized, the belt will slip, making a noise. Disregard any chirping, squealing, or rolling sounds from inside the pump. These are normal when it is turned by hand.
3. Check the hoses and connections for leaks. Hissing or a blast of air is indicative of a leak. Soapy water, applied lightly around the area in question, is a good method for detecting leaks.

   Fig. 1: Troubleshooting the air injection system AIR INJECTION SYSTEM DIAGNOSIS

Air Output

1. Disconnect the air supply hose at the anti–backfire valve.
2. Connect a vacuum gauge, using a suitable adaptor, to the air supply hose.

   NOTE: If there are two hoses, plug the second one.

3. With the engine at normal operating temperature, increase the idle speed and watch the vacuum gauge.
4. The air flow from the pump should be steady and fall between 1.5–6 psi (10–41 kPa). If it is unsteady or falls below this, the pump is defective and must be replaced.

Pump Noise Diagnosis

The air pump is normally noisy. As engine speed increases, the noise of the pump will rise in pitch. The rolling sound the pump bearings make is normal. But if this sound becomes objectionable at certain speeds, the pump is defective and will have to be replaced.

A continual hissing sound from the air pump pressure relief valve at idle, indicates a defective valve. Replace the relief valve.

If the pump rear bearing fails, a continual knocking sound will be heard.

Anti–Backfire Valve

1. Detach the air supply hose which runs between the pump and the gulp valve.
2. Connect a tachometer and run the engine to 1500–2000 rpm.
3. Allow the throttle to snap closed. This should produce a loud sucking sound from the gulp valve.
4. Repeat this operation several times. If no sound is present, the valve is not working, or the vacuum connections are loose.

Check Valve Test

1. Before starting the test, check all of the hoses and connections for leaks.
2. Detach the air supply hose from the check valve.
3. Insert a suitable probe into the check valve and depress the plate. Release it. The plate should return to its original position against the valve seat. If binding is evident, replace the valve.
4. With the engine running at normal operating temperature, gradually increase its speed to 1500 rpm. Check for exhaust gas leakage. If any is present, replace the valve assembly.

Air By–pass valve (EA62 Only)

Check the air by–pass valve to be sure that it is open when the choke is closed.

If the by–pass valve is not operating in this manner, adjust its operating cable.