Sunday, January 10, 2010

Problems with Electric Fuel Pumps

A knowledgeable gentleman that works for a major automotive parts manufacturer told me the other day that his employer loses tens of millions of dollars per year because of new fuel pumps that are returned as defective and they are not defective. I know from personal experience that this is a problem. A local mechanic charged me $1200 in parts and labor and was not able to fix what turned out to be a fuel problem. Another mechanic chased the problem down to either a corroded connection or a relay in the fuel pump electrical system. He cleaned the corroded connection and replaced the relay and it has been running perfectly since then. When we on site working on Store POS Systems, we look for ideas to help other customers. The other day I saw a fuel pump tester in a parts store. It was quite a gadget. It had a pressure regulator, a battery and connectors for the fuel input and output of the pump. You merely set the pressure regulator for the operating pressure for the vehicle, hook the battery to the fuel pump, hook the hose connections to the fuel pump and start the fuel pump running. Assuming that the fuel pump is good it will pump a specified volume of fuel in a specified time. In reality it will pump a lot of fuel or it won't. At this time there is no doubt as to whether the fuel pump is defective or not. Needless to say this parts store does not send back any fuel pumps unless they are really defective. They also save the mechanics a lot of labor.

If the fuel pump is not the problem, it requires a lot of labor to chase down the problem in the fuel pump electrical system. You have to drop the tank and make several voltage measurements on the fuel pump electrical system with the fuel pump under full load. You are usually looking for a measurable voltage across some part of the electrical system. In reality the only measurable voltage should be across the fuel pump itself.

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posted by MIB @ 10:00 AM