The sounds and sights of people washing their vehicles have already begun, but when taking cleanliness into consideration, it’s important to remember that it’s not just the external parts that need to be kept clean. Even more important is making sure the internal systems are running clean – particularly when it comes to the fuel system, as contamination is the leading cause of fuel pump failure.
Unlike brakes, belts, hoses and other parts that are easily and quickly inspected during regular maintenance, the internal workings of the fuel pump and fuel system are more challenging to inspect. That doesn’t mean it’s any less important to make regular inspections, even if it takes longer and requires a more thorough examination.
Rust Never Sleeps
“The main cause of fuel pump failure is contamination. Hopefully the gas station you’re getting your fuel from has some sort of a filtering system and it is actually working,” said Shane Neuman, tech line manager for fuel pumps at Airtex. “If it’s not, then you can pick up contamination whenever you’re filling the tank. It can come from the environment with the gas cap off.”
Inspecting the inside of the fuel tank for rust and dirt will go a long way towards ensuring the long life of a fuel pump. Service technicians can also make it a habit to check the filler neck for signs of rust; as well, ensure the gas cap has not mysteriously gone missing. In older model vehicles, technicians should check for rust on the metal lines. Moisture is a good indication that rust may eventually be a problem, so take note of any dampness on the lines and keep an eye out for forming rust. Newer model vehicles use plastic lines, so rust is becoming an issue related more to the fuel tank and filler neck.
With proper fuel filter changes every 25,000 to 30,000 km, a fuel pump can last at least 150,000 km – or even the entire lifespan of the vehicle.
As with any other part in a vehicle, the fuel pump is bound to fail at times, but too frequently the pump takes the blame when it’s actually another part of the fuel system, the ignition or another part that has caused concern.
“Sometimes [technicians] don’t put the pressure gauges on to confirm the problem, so they go and change other things that could do that,” said Frank Manzone, service advisor at Spectra Premium. Manzone is responsible for inspecting the fuel pumps that are returned and testing them for why they failed. Sometimes those parts are returned still in proper working order, which means the pump became the scapegoat for another part’s failure.
Time for a Closer Look
Proper diagnosis is critical, and although it takes a few extra minutes, taking the appropriate steps to diagnose a potentially faulty fuel pump will go a long way towards improving customer satisfaction and getting the job done right the first time.
Neuman noted that it’s easy to rely on nothing but the onboard computer system for diagnosis or by using an oscilloscope. Each of those represents only a piece of the diagnostic puzzle, though. Proper diagnosis can start with the onboard computer, but it’s a good idea not to fully rely on it. On-board diagnostics systems will show what system pressure is, but knowing there is too much or not enough pressure in the fuel system isn’t enough to confirm a bad pump. It could be the regulator or several other parts that have become faulty.
Taking the vehicle for a road test will help to see how the vehicle responds during acceleration, which could present indications of fuel system problems. A fuel pressure gauge will enable the service technician to compare system pressure to the manufacturer’s specifications, and that could lead to discovering a fuel system problem. The issue needs to be narrowed down to the fuel pump before a replacement is recommended.
“Certain systems can mimic other systems and you think you have a pump failure,” Neuman said. “That’s one of the things we talk about a lot. Until you diagnose it, you don’t know if you have a fuel problem, an ignition problem or something else. Too many people say ‘my aunt’s, uncle’s, brother’s car had a fuel pump and it was doing the same thing, so mine’s the fuel pump, too.’ No, you can’t do that. You have to do a proper diagnosis.”
Remember, No Two Systems are the Same
However, the diagnostic process can vary because of differences in fuel systems between manufacturers and models.
“Because of the great variety of vehicle fuel systems in use today, the diagnostic process can vary. In most cases, digital voltmeters/ammeters and pressure/flow gauges are necessary to test the electrical and fuel portions of the fuel system. Scan tools and oscilloscopes can also be valuable to the diagnosis process, but may not be necessary. Once the test data is obtained, it can be compared to the published specifications to determine if there is a problem and the appropriate repairs can be determined and made,” said Charley Gipe, training operations lead engineer at Delphi Product & Service Solutions.
Gipe said technicians should use a strategy-based diagnostic process and develop a systematic process to check the different parts of the fuel system.
There are several problems that mimic a failed fuel pump. Hesitation or lack of power while accelerating could be a faulty transmission. A misfire or a bucking vehicle during acceleration could be caused by a failing ignition system.
After careful diagnosis, if the fuel pump really is to blame and needs to be replaced, there are some best practices to keep in mind when doing the replacement – and much of it returns to cleanliness. The most common advice given by experts is clean the tank every time.
“The one major thing is to clean the tank because one of the highest percentages of failures is due to contamination,” Neuman said.
Putting a brand new fuel pump on a dirty tank will result in the same problem returning some ways down the road. Other than that, swapping out the fuel pump is like any other parts change. Follow OE vehicle service procedures and things should go smoothly, but Gipe offered a simple checklist of service tips to ensure long life for the replacement pump:
Inspect and clean or replace the fuel tank and fuel lines.
Install a new strainer on the fuel pump (if applicable).
Inspect and replace any damaged vehicle wiring or electrical connectors in the fuel system.
Inspect the failed fuel pump to determine why it failed and make any necessary repairs so the problem doesn’t reoccur in the future.