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 MANUALSPONTIAC1987GRAND PRIX BROUGHAM, 5.0 HREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEM4.3L TBI TESTS W/CODESCHART A7 - FUEL SYSTEM DIAGNOSISCHART A7 (2 OF 2) - FUEL SYSTEM DIAGNOSIS
1987 Pontiac Grand Prix Brougham, 5.0 H
Chart A7 (2 Of 2) - Fuel System Diagnosis
1987 Pontiac Grand Prix Brougham, 5.0 HSECTION Chart A7 (2 Of 2) - Fuel System Diagnosis
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- Has regulated fuel pressure, but pressure is less than 9 psi (.6 kg/cm2
). Check the following when this condition occurs:
- Amount of fuel to injectors is okay, but pressure is too low. Fuel system will be running lean and may set Code 44. Also exhibits hard starting cold and poor overall performance.
- Has restricted fuel flow causing pressure drop. Normally, a vehicle with a fuel pressure of less than 9 psi (6.2 kg/cm2 ) at idle will not be driveable. However, if the pressure drop occurs only while driving, the engine will normally surge, then stop, as pressure begins to drop rapidly.
- Restricting the fuel return line allows the fuel pump to develop its maximum pressure (dead head pressure). When battery voltage is applied to the fuel pump test terminal, pressure should be 13-18 psi (90-124 kg/cm2 ).
- This test determines if the high fuel pressure is due to a restricted fuel return line or throttle body pressure regulator malfunction.
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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.