The heart of your electronic fuel injection system is the fuel pump. This is usually situated in or near your fuel tank. Its job is to push fuel out of the tank to the injectors and create enough pressure for the injectors to deliver adequate fuel in any operating conditions. This pressure must also meet vehicle requirements as stated by the manufacturer. If it doesn’t your engine performance, fuel economy and emissions can suffer.
The Importance of Flow and Pressure
A fuel pump not up to OE flow or pressure requirements can cause problems with emissions and operation of your car. A weak pump that cannot produce enough pressure may disrupt the calibration of the fuel system. This can result in your engine starving for fuel, hard starting, poor idling, hesitation or lack of power.
If you need to replace your fuel pump, make sure you use a replacement that meets all OE specifications. Many brands do not, so be careful when you buy a new fuel pump. Is a cheaper model worth the risk of causing serious damage to your fuel injection system?
What Causes Fuel Pump Failure
When you start up your car, your fuel pump goes to work. After years of work they experience wear. The armature bushings, commutator, brushes, pump vanes, gears, and rollers gradually lose pressure and flow. This wear is accelerated if sediment or rust makes its way past the in filter sock. In some cases your pump fails because contaminants have entered the fuel pump and clogged it. This causes overheating and your motor will burn out. Fuel starvation can also accelerate wear because your fuel pump relies on the fuel for lubrication and cooling.
Diagnosing Fuel Pump Problems
In the event your fuel pump stops working, the first place to look is the pump voltage supply and electrical connectors. Look for an open relay, loose wire or blown fuse. If your battery voltage is too low the pump will not be able to generate enough pressure.
If these are fine, then you will need to measure the fuel delivery and static output pressure. If either of these is below the manufacturer specifications, you will have to replace your fuel pump.
Replacing Your Fuel Pump
Choosing the right fuel pump means more than just the right make, model, year and engine size. It means selecting one that meets every OE performance specification and fits like the original. Many companies have consolidated parts to make a few pumps fit a variety of cars. This can cause performance problems and the fuel pump won’t fit properly.
Comparisons showed these glaring shortcomings from some brands:
1. One fuel pump covered 70 OEM part numbers, however the fuel delivery was 42 to 50 percent less than required by OE specifications
2. Another pump also covered 70 OEM part numbers, yet had the fuel delivery of 25 percent below OE specifications
3. The third competitor covered an astounding 153 OEM part numbers, but fuel delivery was 30 to 42 percent less and exceeded electrical usage as much as 33 to 50 percent
4. Some competitors actually use different sizes or types than the original. A 38 mm in diameter pump is supposed to be able to replace a 51 mm pump? To help you make it fit you are given a rubber sleeve! If that isn’t bad enough, the outlet pipe is off-center causing the fuel pump to stick out nearly an inch more than an OE pump.
5. Another trick employed by competitors is using the same inlet filter screen for various cars. This means a poor fit in most cases because of the variety of shapes manufacturers use in the fuel pot reservoir.
Important Things to Remember
When installing a new fuel pump avoid problems by remembering:
1. Inspect the inside of the tank and clear away any debris or rust. Installing a new pump into a dirty tank will result in premature failure
2. When replacing an in-tank pump, disconnect the battery first or you may get unwanted sparks. Drain the tank before you remove the tank straps and open the retaining collar. Make sure you don’t have any flames or sparks nearby
3. When replacing your fuel pump, replace the filter screen too and install a new gasket or O-ring on the sealing collar
4. Never jump test your new pump before installation. If you run a fuel pump dry you will damage it. Test only after fuel has been put in the tank. Replace rubber or braided fuel lines showing signs of flaking or cracking with proper EFI hoses.