Just about every automobile on the road today with a gas motor is equipped with an electric fuel pump. If you own a car; chances are it has an electric fuel pump.
Prior to fuel injection there was the carburetor. Carbureted engines had a mechanical fuel pump mounted on the engine. This style of pump usually was driven off of an eccentric lobe on the camshaft.
Carburetors did not need a lot of fuel pressure to feed them; in turn created a small problem with this style of setup. The combination of low fuel pressure and heat generated either by the engine and/or outside ambient temperatures (hot weather) or the combination of both; caused the fuel to vaporize (vapor lock).
Mechanical fuel pumps were not designed to pump vapor. Vapor locking caused the vehicle to spit, sputter and sometime just die; when the engine finally cooled down then the vehicle would start up just fine.
Most electric fuel pumps are located in the fuel tank of your automobile. There are several reasons why the manufacturers mounted this style of pump in the fuel tank:
o When fuel injection came around; this system required higher fuel pressures to function properly. Electric fuel pumps were designed to pump fuel at high pressure. The combination of higher operating pressures and mounting these pumps in the fuel tank; eliminated any possible vapor locking.
o Keeping the fuel pump submerged in fuel; keeps the pump cool and allows a constant supply of fuel to the engine. Plus; with the fuel pump submerged in fuel, there is a least likelihood of an explosion. Liquid fuel does not explode, fuel vapors do.
o The benefit of having a fuel pump mounted in the tank is that a suction style pump at the engine could suck in air through a bad connection. This is a hard problem to diagnose, but a leaking connection in a pressurized line is a lot easier to see.
A potential hazard of electric fuel pumps is that all the lines are pressurized from the tank to the engine.
Although mechanical fuel pumps may be safer than the electric fuel pumps; (because of the lower pressures required for mechanical fuel pumps) they are also cheaper to purchase and replace compared to the electric fuel pump.
Here are two reasons why electric fuel pumps are more expensive to replace:
o Component: The electric fuel pump is a more complex component compared to the old mechanical pumps. Buying an electric fuel pump over the counter from your local parts store will vary depending on the make and model of your vehicle. An aftermarket brand pump will run somewhere between $75.00 to $150.00, that’s being conservative. Buying a genuine manufacturer pump will run you considerably more.
o The fuel tank usually has to be removed in order to replace the fuel pump. This procedure requires a lot more time and labor. Having your local repair shop tackle this procedure will be quite expensive.
One of the hard facts to remember is that most electric fuel pumps prematurely fail due to improper maintenance. This fact reference comes from 20 years of being in the automotive and truck industry.
Here are Robb’s top three reasons why electric fuel pumps fail prematurely; in order:
o Plugged Fuel Filter: Unless you have a local shop who takes care of all your vehicle service and maintenance; most people overlook replacing the fuel filter.
Many people don’t even know that a fuel filter exists on their vehicle. As the fuel filter becomes more restricted through time; the pump has to work harder to push fuel through the system.
The more restricted the filter becomes the harder the pump has to work, eventually burning up the fuel pump. Replacing the fuel filter every 15,000 to 20,000 miles will help get the longest life out of your electric fuel pump.
o Running Off The Low Side Of Your Fuel Tank: Constantly running your vehicle below a ¼ tank causes the fuel pump to overheat. Remember earlier I mentioned that having the pump submerged in fuel keeps the pump running cool.
Filling your tank up before it gets below a ¼ is a good habit to get into. It will also prolong the life of your electric fuel pump.
o Cheap Fuel: Fuel that has an ethanol blend in it is usually cheaper to purchase at the pump. Your vehicle may not be equipped to handle ethanol blended fuel.
There is usually a tag or sticker under the hood that will specify if your engine is equipped to handle ethanol blended fuel. If you own a newer vehicle, (year 2002 and up) this should not be a problem; I would refer to your owners manual just to be sure.
Ethanol blended fuel does not have the lubricating properties to keep the fuel pump and system o-rings and seals properly lubricated. Higher octane fuel (more expensive fuel) has these lubricating properties.
I suggest adding a fuel additive to your ethanol blended fuel if your vehicle is not equipped to handle this kind of fuel.
I hope this article was informative and my tips and recommendations are helpful. I know what it cost to bring a broken vehicle in the shop to be fixed, it’s not cheap.
Supplying you with a little more understanding and knowledge about your vehicle and electric fuel pump will help keep your vehicle out of the shop. You will also increase the life of your electric fuel pump if you decide to follow these guidelines.
If for some reason your fuel pump does fail and it has to be replaced, at least you will have the knowledge to understand what is going on and be able to relate to what the Service Manager is explaining to you.