Paccar Low Side Fuel System Pressure Testing

Low Side Fuel System Pressure Testing

Target values:

1) Fuel Supply Line:

-1.5 to 0 PSI – See page 3

2) After Primer Pump:

-2.2 to 0 PSI – See page 4

3) After Lifting Pump:

116 to 131 PSI – See page 5

4) Fuel Pressure gallery:

116 to 131 – See page 6, 7 and 8

5) Injector return line:

68 to 91 PSI – See page 9

6) Injector return Flow:

A

B C

E & F

Low Side Pressure Testing points

Measuring point

Description

A Pressure before the manual fuel lift pump (suction side)

B Pressure after the manual fuel lift pump (suction side)

C Pressure after fuel lift pump (pressure side)

D Pressure return line to fuel tank

E Pressure injector leak

F Injector leak flow

Fuel supply line Pressure

(-1.5 to 0 PSI)

Measurement: Pressure measured at quick coupling of fuel supply line on primer pump.

Tooling: T-shaped adapter (Kit P/N 1903030) with the pressure gauge.

Purpose: Determine restrictions in fuel supply lines and couplings between fuel tank and primer pump.

Fail criteria: Less than -3.6 PSI Check for:

 Fuel line blocked or damaged  Failure of quick-release coupling  Tank venting not functioning  Fuel contaminated or gelled

More than 2.2 PSI Check for:

 Tank venting not functioning

Primer Pump Pressure

Measurement: At quick coupling exiting primer pump.

Tooling: T-shaped adapter (Kit P/N1903030) with quick connecters and pressure gauge

Purpose: Determine restrictions in primer pump.

Fail criteria: Less than -5.8 PSI Check for:

 sieve blocked by contamination  tank venting not functioning

 fuel line routing issues, fuel contaminated or gelled

More than 2.2 PSI Check for:

 tank venting not functioning

Lift Pump Pressure

(116 to 131 PSI)

Measurement: Pressure at banjo of fuel line downstream of lifting pump

Tooling: Hose and extended banjo bolt (Kit P/N1903030)

Purpose: Determine restrictions in lifting pump.

Inlet pressure of fuel module to determine clogging of filter

Fail criteria: Less than 87 PSI Check for:

 Fuel lifting pump worn

 Pressure regulating valve in fuel gallery damaged (pg 7)  External fuel leakage

 Internal fuel leakage in fuel filter module More than 203 PSI

Check for:

 Fuel return blocked between fuel pump and tank

 Pressure regulating valve in fuel gallery damaged (pg 7)  Plugged fuel filter

Pressure in Fuel Gallery (Electrical)

Measurement: Pressure in fuel gallery from ECU

Tooling: DAVIE

Purpose: Outlet pressure of fuel module, used for pressure drop over fuel filter Correct functioning Fuel Gallery Pressure Valve

Fail criteria: Less than 87 PSI Check for:

 fuel pump worn

 pressure regulating valve in fuel gallery damaged (pg 7)  external fuel leakage

 internal fuel leakage in fuel filter module More than 203 PSI

Check for:

fuel return blocked between fuel pump and return tank Less than 58 PSI

Check for:

 fuel filter fully loaded (Plugged)  fuel filter module damaged

Pressure in Fuel Gallery (Mechanical)

Measurement: Pressure in fuel gallery (actual, measured by removing the Fuel Temperature sending unit and installing a pressure gauge)

Tooling:

Purpose:

Fail criteria:

Test conditions:

Outlet pressure of fuel module, used for pressure drop over fuel filter Correct functioning Fuel Gallery Pressure Valve

Less than 87 PSI Check

• fuel pump worn

• pressure regulating valve in fuel gallery damaged (pg 7)

• external fuel leakage

• internal fuel leakage in fuel filter module More than 203 PSI

Check for:

fuel return blocked between fuel pump and return tank Less than 58 PSI

Check for:

• fuel filter fully loaded (Plugged) • fuel filter module damaged

Fuel Gallery Pressure Valve

&

Fuel injector leak valve

 Above the fuel return line is the Fuel Gallery Pressure Valve. The valve is similar to the fuel pressure control valve used on the EPA10 MX13 engine. It is on the low pressure side so it is not subject to the same pressures as the EPA10 valve.

 On the Fuel Return Line is the Injector Leak Valve. Fuel Gallery

Pressure valve

Fuel Injector Leak Valve

Injector Return Line Pressure

Measurement: Pressure at banjo connecting injector return line to engine.

Tooling: Extended banjo, hose (Kit P/N1903030) and pressure gauge

Purpose: Pressure in return line of Fuel injectors, functioning of Injector Leak Valve

Fail criteria: Less than 61 PSI Check for:

 Injector leak valve damaged More than 91 PSI

Check for:

 Injector leak valve damaged  Blocked, damaged return line

Test conditions: Engine running, no load at 1200 +/- 100 rpm

Injector Return Line Flow

Measurement: Flow from injectors

Tooling: Extended banjo, hose (Kit P/N1903030) and beaker

Purpose: Injector bleed flow

Test conditions: Engine Running, no load at 1500 rpm +/- 100 rpm (Fuel rail pressure 36,260 PSI, pressure at this pipe should be 61 to 91 PSI)