Injection & feed pumps
This article covers the differences in how they work and your options if you need to make repairs or replace a pump. The feed pump takes fuel and transfers it to the fuel filter. If the tank is higher than the engine, a feed pump may not be necessary as a gravity feed is possible. The fuel filter removes impurities and the fuel moves onto the injection pump.
fuel and transfers: Pumps
Injection & feed pumps
See the difference between feed and injection pumps
Marine diesels typically have two fuel pumps. One is a low pressure or lift pump. This moves fuel from the tank into the engines injection system. The other is a high pressure or injection pump which provides fuel to the engines injectors.
Yanmar's the feed pumps
On Yanmar's the feed pump is a mechanical/diaphragm pump. On Universal/Westerbeke's the pump is electric, powered with 12V dc, & solenoid operated. Some of the Universal/Westerbke pumps may have a filter that needs to be occasionally changed.
The injection pump then pressurizes the fuel and passes it through the injection nozzle. Additionally the injection pump controls the amount of fuel that is injected and sets the injection timing. The injection pump is the most important part of the entire fuel system.
A well maintained fuel injection system is essential to good performance of your engine. Since pressures are extremely high and tolerances are fine even a small dip in injection performance can be detrimental to your engine's performance.
Incorrect injection pump timing can cause the engine not to start or to be hard to start. It can also cause lack of power or cause your engine to produce white smoke as there is insufficient temperature to properly burn the fuel. A faulty injection pump can be the culprit behind a stalling engine or a rough running engine.
The relative importance of each pump is demonstrated by their pricing. Feed pumps are priced from $ 60 to $ 300. Injection pumps range from $ 500- $ 550to several thousand dollars.
The cost comparison should be taken into mind when it comes to service. Feed pumps may sometimes be serviced by do it your selfers. Injection pumps should not be a DIY project. Either a qualified marine mechanic or a shop specializing in diesel injection should work on injection pumps. The level of precision required in injection pumps makes it a job for professionals with proper equipment.
The bottom line is if you need a lift pump the cost, knowledge and time needed for repair or replacement are less than if you need to replace or repair an injection pump.
Where to find
Whether you need a feed pump or injection pump Marine Diesel Direct can assist you with parts needs.
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