2013 PACCAR MX-13 – P0087 Fuel pressure – Data valid but too low, most severe

Fault code information

1 trip Stop Engine lamp
3 drive cycle recovery
Readiness group – None
Freeze frame type – Fuel

Description of component(s)

Fuel pressure sensor (F801)
The low-pressure fuel pressure is measured at the end of the low-pressure fuel supply gallery.

Effect on the system:
* Limitation of the engine torque when the fuel pressure is too low.

Fuel temperature sensor (F803)
The fuel temperature is measured in the low-pressure fuel supply gallery between the common rail pump units.

Effect on the system:
* Preventing automatic fuel module water draining activation when the fuel temperature is very low           (the water present may be frozen).
* Limitation of the engine torque when the fuel temperature is too high.

The main components of the fuel filtration module are:
* prefilter
* hand priming pump
* fine filter/water separator
* fuel heater
* water-in-fuel sensor/water drain valve
* Activated Carbon filter
* (MX-11) Fuel pressure sensor

Prefilter
This suction side filter is a 300 micron filter. The filter contains two non-return valves
that are necessary for operation of the priming pump.

Hand priming pump
The hand priming pump must be screwed out before it can be operated.

File filter/water separator element
The filter/water separator is a combined filter element. The element has the no filter-
no run feature. The absence of the filter element results in non-starting of the engine.
The use of a non-original filter results in severely reduced engine performance.
The fine filter is a 3 micron filter.

Fuel heater
The fuel heater is a 300-W self-regulating heater (bi-metal switch and PTC). The heater switches ON below +2 ± 5oC and switches OFF above +24 ± 5oC.

Water-in-fuel sensor/water drain valve
The water-in-fuel sensor/water drain valve is a combined component. The water level in the lower bowl is sensed by the water-in-fuel sensor.

If water is present the PCI ECU activates the water drain valve for 1 second to open the entrance to the AC filter canister. A safety valve (floating ball) prevents external drainage of fuel.

Activated carbon filter
When the AC canister is full, the clean water is drained to the environment.

Fuel pressure sensor
MX-11
Connections

Location of component(s)

Fuel pressure sensor (F801)

Fuel temperature sensor (F803)

Fuel filtration module (L097)

Diagnostic condition

This diagnostic runs when the engine is running for more than 200 seconds.

Set condition of fault code

The PCI ECU (D420) detects that the fuel pressure is too low (gray area of the graph)

Reset condition of fault code

This DTC changes to inactive when the fault is no longer detected.
To validate the repair, key off the ignition for at least 15 seconds, then key on again. Start the engine and operate it at several engine speeds of the engine speed range for more than 25 seconds.

Electrical diagram(s)

Checking data, fuel pressure sensor (F801)

Checking data, fuel temperature sensor (F803)

Technical data

Component and wiring check, fuel pressure sensor (F801)
Component check, fuel pressure sensor (F801)
This type of component cannot be checked with a multimeter or oscilloscope.
Perform the following to assess the component:
* Monitor/test the component with DAVIE
* Perform the wiring check

Component & wiring check, ECU (D420)
Preparation
• Key off the ignition.
• Disconnect connector F801
• Measure on the front side of wiring harness connector F801

Component check, fuel temperature sensor (F803)
Preparation
* Key off the ignition.
* Disconnect connector F803
* Measure on component connector F803

Component & wiring check, ECU (D420)
Preparation
* Key off the ignition.
* Disconnect connector F803
* Measure on the front side of wiring harness connector F803

Possible causes

Restriction in the fuel supply or low performance of the fuel lift pump.
Items to check:
* The position of the nonreturn valves and the cleanliness of the fuel sieve in the hand primer pump,             using the job, “replace strainer (Fuel system), job ID 66976.”
* Fuel pressure according to the job, “check fuel system low pressure (Fuel system), job ID 68720.”

Additional information

* The low-pressure fuel pressure is measured by the fuel pressure sensor (F801).
* Engine torque is reduced (derate) with this DTC active.

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