Close valve on pressure gauge. With engine off, operate fuel pump. Pressure should rise to level specified in "Pressure Testing" chart.

If pressure is too low, check fuel pump output. Disconnect fuel return line from fuel distributor and run a hose from fuel distributor to container. Operate fuel pump and measure output after 30 seconds. If not as specified in "Fuel Pump Flow" chart, check fuel lines, filter, accumulator and pump.

Fuel Pump Flow Specifications

Application		Flow in 30 Sec. oz. (cc)
BMW, Peugeot, Porsche		24 (750)
Audi, Saab, VW		30 (900)
Mercedes-Benz		32 (1000)
Volvo
	Turbo	35 (1050)
	All Others	27 (800)

If pressure is too high, check for kinked or blocked fuel return line. If lines are clear, system pressure regulator must be adjusted. Turn pump off, loosen return line fitting, and relieve pressure.

Fig 1: Pressure Regulator in Fuel Distributor
Courtesy of NOT AVAILABLE
Loosen line pressure regulator nut. Remove shims, spring(s) and plunger. Raise system pressure by adding shims; lower pressure by removing shims. Be sure "O" rings are in good condition. If plunger is scored or damaged, fuel distributor must be replaced.

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.

Safety Warning

System (Line) Control Pressure Test

Use the Manual With the Right Hardware

When to See a Mechanic