HOUSING AS 1421708 - Caterpillar

Introduction
The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, use the solution that is identified below.Problem
There have been a number of isolated instances of issues with electric fuel lift pumps on C7.1 and C6.6engines. If the supply of fuel to the electric fuel lift pump is insufficient, the engine may be derated or the engine may stop. The following symptoms may also be apparent:
Electric fuel lift pump is noisy
Low fuel pressure
High fuel temperature
The fuse or circuit breaker for the electric fuel lift pump may blow or trip
The fuse or circuit breaker for the electric fuel lift pump relay may blow or trip
On C7.1 engines, the diesel particulate filter may not regenerate due to low fuel pressureThe issue can arise due to either of the following reasons:
A restriction of the fuel supply from the fuel tank to the electric fuel lift pump
An overvoltage in the electrical supply to the electric fuel lift pumpSolution
Note: All the affected engines have a return fuel connection banjo bolt on the secondary fuel filter with a smaller orifice. The smaller orifice will restrict reverse fuel flow in a situation where fuel flow from the electric fuel lift pump is insufficient. The reduced flow will cause the engine to be derated or the engine will stop.Perform the following procedure to check the fuel supply to the electric fuel lift pump:
Illustration 1 g03587764
Typical low-pressure fuel system (1) Fuel Tank (2) Fuel isolation valve (3) In-line fuel filter (4) Electric fuel lift pump (5) Fuel return line (6) Primary fuel filter
Make sure that there is sufficient fuel in the fuel tank. If necessary, replenish the fuel tank. Make sure that the correct specification of fuel is used.Note: When performing the following fuel system tests, the Electric Fuel Lift Pump (EFLP) will only operate for 2 minutes unless the engine is running. If necessary, cycle the keyswitch in order to reactivate the pump.
Turn the keyswitch to the OFF position and then disconnect the electrical connector from the EFLP.
With the keyswitch in the ON position, record the voltage at the harness connector for the EFLP. The voltage must be between 20 VDC and 28 VDC. If the voltage is below 20 VDC, investigate the cause.
Turn the keyswitch to the OFF position and then reconnect the electrical connector to the EFLP.
Disconnect the fuel inlet from the primary fuel filter. Place the open end of the disconnected line into a calibrated container.
With the keyswitch in the ON position, measure the flow from the fuel line. Refer to Illustration 2 for the minimum acceptable fuel flow.
Turn the keyswitch to the OFF position and then reconnect the fuel inlet to the primary fuel filter.
Illustration 2 g02527518
Minimum EFLP flow rateNote: In the following steps, use a suitable container to collect the drained fuel.
If the flow rate is less than specified, disconnect the fuel line between the in-line fuel filter and the EFLP. Check that sufficient fuel flows from the line.
If the flow from the line is