Troubleshooting any diesel or gasoline fuel system

Any diesel or gasoline internal combustion engine requires fuel


supply (flow and pressure) to start. Although many different types


systems, they are all similar in basic fuel delivery. Most systems have some


a kind of low pressure pump that delivers fuel at a low pressure of 3-80 psi to the main


source of delivery at higher pressure to the combustion chamber through some form


injection or carburetor device for supplying and spraying fuel.

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The first step in any diagnosis is to test the fuel at the correct pressure for that engine.


a specific engine after transferring fuel or booster/primer pump. These pumps


either electrical or mechanical, and may be in the fuel tank, or externally closed


to the tank (electric feed pump) or mechanical pump mounted on the engine


and run through a cam or, in some cases, a gear pump mounted on the diesel itself.


High pressure fuel pump or built into high pressure fuel pump.

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pressure and fuel flow are straight forward with electric pumps. Turning off


feed pump output, fuel pressure/flow rate can be seen and measured.


If there is no flow/pressure, check that the pump has the correct


Voltage. Many problems arise with wiring, fuses or relays,


preventing the pump from building up pressure/flow.

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in some cases, the pump may work, but the mesh is clogged


tank filter. we have had cases where we had to apply air pressure to


a line going to the tank to "blow out" a clogged filter in the tank. If


in this case, the removal and cleaning of the tank will be required. Eat


several tank mount designs, some have multiple strainers that can be plugged but can also be cleaned and reused. This is especially true for


diesel engines, as they are much more prone to algae growth in the tank.

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the same flow/pressure test method can be used with an external


installed mechanical pumps in the engine compartment. Gear pumps built


internally with the injection pump of diesel fuel can only be checked with very


specialized equipment for the restoration of high pressure fuel pumps and


at the testing stage. At AMBAC, each type of injection pump is carefully


is tested during the recovery process to ensure it meets or exceeds the requirements.


OEM specification. As the official manufacturer of all USMC diesel engines.


equipment, AMBAC prides itself on its strict standards.

Once


fuel pressure/pressure meets OEM specifications, we can exclude


feed/lift/pump/rail pump as part of the problem and move on to the actual


fuel injection or delivery systems for the next troubleshooting step (see


fuel systems troubleshooting blog).