Power Valve Test
- Disconnect vacuum hose to power valve. Connect hand vacuum pump to power valve. Apply vacuum. Vacuum should remain steady. If vacuum decreases, replace diaphragm and re-test. If vacuum remains steady, proceed to next step.
- Reconnect vacuum hose to power valve. Start engine and allow to warm up. Disconnect hose from power valve and connect a vacuum pump to the hose. Vacuum should not be present. If vacuum is not present, proceed to step 4). If vacuum is proceed to next step.
- Check for voltage at power valve control solenoid valve connector (Yellow wire). If there is voltage, replace power valve control solenoid valve and re-test. If there is no voltage, check and repair fuse, wiring or speed sensor and re-test.
- Jack up front of vehicle and support with safety stands. Block rear wheels and apply emergency brake. Place transmission in 2nd or "D". Check for vacuum at power valve hose No. 14. above 15 MPH. See Figure . If vacuum is present, proceed to step 7). If no vacuum is present, proceed to next step.
- Check for voltage at power valve control solenoid valve (control box connector Yellow wire). If there is voltage, replace speed sensor and re-test. If no voltage is present, disconnect the hose No. 18 at check valve inlet side and check for vacuum. If vacuum is present, check the check valve operation. If check valve is okay, replace power valve control solenoid valve and re-test. If no vacuum is present, disconnect the hose from choke opener and check for vacuum at the opener.
- If there is no vacuum at the opener, remove the opener and clean carburetor port and re-test. If vacuum is present at the opener, check and repair the vacuum lines as necessary. If no problem is found with vacuum lines and vacuum is still not present at power valve above 15 MPH check thermovavle A and cranking leak solenoid valve. Re-test.
- With speed still above 15 MPH, disconnect hose No. 20 from the vacuum pipe manifold to emissions box. See Figure . Check for vacuum at hose No. 14 to power valve. If vacuum disappears, the system is okay and test complete. If vacuum did not disappear, check for continuity across the vacuum switch in emissions box with hose No. 20 disconnected.
- If there is continuity, check for voltage to the power valve control solenoid valve with speed above 15 MPH. If there is voltage, replace power valve control solenoid valve and re-test. If no continuity is present, replace vacuum switch and re-test.