Fuel pumps have been a leading course of discussion as of late, because of their cost and seemingly ability for them to fail without warning and in waves. Actually the word fuel pump is politically incorrect as it applies to today’s vehicles. They should really be called fuel pushers today.
The mechanical fuel pump is like any mechanical pump from the earliest type that sucked water from the ground to the type that mounted on the block of an engine. Every mechanical pump is the same. Basically it is a rod attached to a diaphragm that when stroked causes a vacuum that sucks the fuel from the tank to the opposite side of the diaphragm which is then pushed to the carburetor or injectors.
In the older days of carburetors, fuel pumps had to produce relatively little pressure to get enough fuel to the carburetor bowl. In fact we mechanics were more worried about the vacuum side of the pump than the pushing side. We generally looked for 10 inches of vacuum and 4 lbs. of pressure as the guideline for a healthy pump.
Fuel injection was primarily used in European vehicles thanks to Robert Bosch. Bosch injector systems were standard in most European vehicles; their fuel pumps were externally mounted in close proximity to the fuel tank. Vacuum was almost not necessary at all because of the closeness of the pump to the tank. It was almost a gravity system. The pressure side was substantially higher usually between 50-75psi.
As domestic vehicles became fuel injected, fuel pumps were being installed in the fuel tanks and pressures fluctuated from 9-13 psi, to 35psi, to split demand pumps that would demand as high as 64psi to start the engine and then step down to 54 psi to keep the vehicle running, to the newest models that now have a low pressure pump to get the fuel to the high pressure pump which will generate up to 2200psi on gas fired cars to 3100psi on turbo diesel pickups.
Now frankly just how much is due to the pump itself? Relatively little, most pumps can warp up to a higher rpm on demand if a vehicle needs it but for the most part it’s the fuel pressure regulator that controls this. These regulators show up in the craziest places: the early Mercedes was built into the fuel filter, most early domestics ended up in the return side of the fuel rail, and now with the advent of return less fuel systems the regulator as become a part of the pump.
This is just one of the reasons that the price of fuel pumps have been climbing. To add even more cost to this pump, manufactures have incorporated the fuel sending unit onto the pump as a way to decrease the cost of fuel tank manufacture and to make electrical circuits and harness’ easier to consolidate. Thus if your fuel pump stops pumping, you need a fuel pump.
If the pressures going to the injectors are too high or low, you need a fuel pump, or if your fuel gauge stops working or becomes in accurate you need a fuel pump. With the average cost of fuel pumps running about $500.00 and the labor to replace them between $300.00 and $400.00, expect the bill to run between $800.00 and $1000.00. That my friend’s is a chunk of change in anyone’s book.
So what is the way to increase the reliability, and to decrease the cost of ownership of your fuel pump?
First: Make sure that you use a quality TIER 1 FUEL. This means brand names only, BP, Sunoco, Shell, Marathon, Chevron, etc.
Second: Remember that the fuel pump is an electrical motor, and that it heats up. The manufacturers have put the fuel pump in the fuel tank so that it can remain cool, try to never run the fuel level down below a half tank. This insures that the pump will stay immersed all the times.
Third: Never get fuel if the station is getting fuel at the same time. All of the dirt and deposits are be stirred up and the gasoline pump filters can never catch it all.
Fourth: If your vehicle has a fuel filter that is not in the tank, change it yearly, regardless of how many miles that may have on the vehicle.
Fifth: If you are not burning a tank of fuel every week to 2 weeks make sure that you add an anti-ethanol agent so that the fuel does not jell. This fuel separation is the single most cause of fuel pump and injector failure.
So the lesson should be that if you trying to save money by using poor fuel choices, or by not changing your fuel filter in a timely manner, or by running your fuel tanks to the bottom, consider this. An $800.00 fuel pump repair would be 7 years of fuel filter changes. Which is easier to come up with, $120.00 a year for 7 years or a fuel pump for $800.00 in year 4 or 5?
If times are tough and you can only afford $20.00 a week in fuel, bite the bullet one week and fill it up and then go back to putting $20.00 a week on the top side of the tank. It’s the same money just the difference of having a full tank with a cool fuel pump or an empty tank with a tired overheated pump.
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