System (Line) Pressure Test
- Install valve between pressure gauge and control pressure regulator. See TEST EQUIPMENT HOOK-UP in this article. Hang gauge from convenient point above level of units to be tested.
- Close 2-way valve to stop flow-through of fuel. Unplug connector at mixture control unit. Turn ignition on. System pressure should be 64-74 psi (4.5-5.2 kg/cm2
).
- If system fuel pressure is too low, check for leaks at fuel lines or connections. Check for a clogged/restricted fuel filter, improper fuel pump delivery rate, or incorrect system pressure adjustment.
- If system fuel pressure is too high, check for clogged/restricted fuel return line, incorrect system pressure adjustment, or pressure regulator control piston binding
- If necessary, adjust system pressure by adding or removing shims to pressure regulator. Pressure will change by 4 psi (0.3 kg/cm2
) by a 0.020" (0.5 mm) shim.
- Transfer valve should open at 50-57 psi (3.5-4.0 kg/cm2
). See Fig 1. If not, engine will be difficult to start. Check by replacing valve and restarting engine.
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