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.
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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - BASIC DIAGNOSTIC PROCEDURESBASIC FUEL SYSTEM CHECKS (DIESEL ENGINES)FUEL SYSTEM PRESSURE TEST
1999 GMC Forward Control 5.7 R, Automatic
Fuel System Pressure Test
1999 GMC Forward Control 5.7 R, AutomaticSECTION Fuel System Pressure Test
NOTE:
For fuel pump circuit testing, see appropriate FUEL SYSTEM ELECTRICAL CIRCUIT under NO START DIAGNOSIS .
- Turn ignition off. Install tee adapter and pressure gauge at injection pump. Start engine and measure fuel pressure.
- If fuel pressure is not 4 psi (.28 kg/cm2 ), check fuel lines and fuel tank sending unit for restriction. If fuel lines and sending unit are okay, replace fuel pump.
RENDER: 1.0x
NO RELATED
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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.