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.
Over-Boost Protection
The 300 series is equipped with an over-boost protection circuit, consisting of a pressure switch, switch-over valve and wiring. When boost pressure exceeds 16 psi (1.12 kg/cm2 ), the pressure switch closes, grounding the switch-over valve.
The valve vents manifold pressure which would otherwise affect the aneroid compensator on the injection pump. This reduces the quantity of fuel injected and engine speed.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.