LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Buick >> 1995 >> Roadmaster Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Testing >> Basic Fuel System Checks (A-7) >> Fuel System Pressure Test >> Fuel Pressure Check
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Fuel Pressure Check

  1. Relieve fuel pressure as previously described in FUEL PRESSURE RELIEF. Connect Fuel Pressure Gauge (J-34730-1) to fuel pressure fitting on fuel rail. With gauge installed, turn ignition on. With ignition on and engine off, fuel pressure should read within specification. See FUEL PRESSURE  table. If no fuel pressure is present, go to step 5).
  2. Start engine. Pressure should drop 3-10 psi (.2-.7 kg/cm2 ). Turn ignition off. Pressure should hold. If pressure does not hold, check for leaking injectors or fittings. If injectors or fittings are not leaking, replace pressure regulator.
  3. If pressure is present but less than specification, check for restricted delivery line or fuel filter. Repair as necessary. If no restriction is evident, apply battery voltage to fuel pump test connector using a 10-amp fused jumper wire. For location of fuel pump test connector, see COMPONENT LOCATIONS in appropriate I - SYSTEM & COMPONENT TESTING article in the ENGINE PERFORMANCE section.
  4. Gradually pinch off fuel return line between gauge and fuel tank. If fuel pressure increases to within specification, replace fuel pressure regulator. If fuel pressure does not increase with line pinched, check for faulty in-tank fuel pump or partially blocked fuel strainer.
  5. Apply battery voltage to fuel pump test connector using a 10-amp fused jumper wire. For location of fuel pump test connector, see COMPONENT LOCATIONS in I - SYSTEM & COMPONENT TESTING article in the ENGINE PERFORMANCE section. Observe fuel pressure reading. If fuel pressure is still not present, check wiring between test connector and fuel pump. If wiring is okay, replace fuel pump.
  6. If fuel pressure is present with voltage applied to test connector, test fuel pump relay and voltage supply to relay. See I - SYSTEM & COMPONENT TESTING article in the ENGINE PERFORMANCE section.
FUEL PRESSURE

Application psi (kg/cm2 )
All Models 41-47 (2.88-3.30)