Replacing Your Fuel Pump

Let's talk about fuel pumps. Have you ever gone out to your car, got behind the wheel and attempted to start the engine only to get a lot of cranking and no starting? Chance are good the problem is limited to only two different car systems. Electrical, or fuel. Sometimes, a combination of the two.

It used to be with cars and trucks that the fuel pump was attached directly to the engine block. The pump had a rather long spring loaded arm projecting from it and this arm fit up in a cavity on the side of the block. In there, was a lobe of the engines cam or crank. This lobe would press down on that arm during the engines revolution as the lobe rotated thereby pressing this arm in a downward motion. This motion operated a rubber diaphragm and valve arrangement within the pump....which sucked fuel from the tank. The fuel would travel via steel line from the tank and into the pump..where a valve would then allow the fuel to pass to a second line leading to the carb. The arm being spring loaded would then return to its original position as soon as the cam lobe was past. This up and down motion of the pumps internal parts served to suck fuel in from the tank, and then push it out to where it was needed.

That was then ! These days our vehicles have need of a more sophisticated method of fuel delivery and the electric fuel pump is now among us. People of the racing stripe have long used electric pumps as they realized that a steady stream of fuel was needed for the fuel injection systems. These days, most vehicles are fuel injected as it is more efficient.

I recall going out to my elderly truck one day to drive to work and finding that I had lots of crank and no start. A splash of lawn mower gasoline into the throat of the Throttle Body Injector system allowed the engine to start right away. This told me that everything was working as it should be..except the fuel delivery system..and that meant the fuel pump. And THAT meant..dropping the fuel tank to get at it.