Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
High Altitude Compensation System: Operation: Gas
At high altitudes (above 4000 ft.), fuel supply is decreased in the same proportion as the air density. Normally, the control pressure is regulated by a diaphragm and a spring. To achieve altitude compensation, another diaphragm with a spring and a chamber have been added. See Fig 1 .
The chamber maintains a constant low altitude (below 4000 ft.) pressure while the pressure outside it varies according to altitude. The pressure difference causes the diaphragm to exert more or less pressure on the inner spring.
At increasing altitudes, decreasing pressure outside the diaphragm chamber causes the lower diaphragm to rise. The resulting increase of pressure on the upper diaphragm increases control pressure. This provides a correct air/fuel mixture.
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.