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.
1994 GMC Forward Control 7.4 NFACTORY OEM SERVICE PROCEDURE
Fuel System Checks
- Check the Supply to injection pump. Refer to BASIC TESTING - 6.5L DIESEL
- Check for air in fuel system. article
- Check the fuel return from injection pump. Refer to BASIC TESTING - 6.5L DIESEL article
- Check engine shut-off solenoid operation.
- Check the fuel injection nozzles. See INJECTORS
- Check the fuel tank cap vent.
- Check for an internal injection pump problem.
Factory Service Tools
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.
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