Fuel Pump Inspection Guide: Easily Master Inspection Points

Does the car have difficulty accelerating (especially on the highway)? Is your car showing signs of low fuel? The fuel line, filter, pump, or injectors are most likely clogged or partially clogged.
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If you’re having trouble starting your car, do a quick test of your fuel pump to determine if this is the culprit. Continue reading this article for more details!

Perform Electrical Testing

Check the fuel pump fuse. Often it’s not the fuel pump that fails, but the electrical supply. Consult the owner’s manual to locate the fuse box and then locate the fuse that corresponds to the fuel pump. Remove the fuse and check for signs of failure. The fuse may have melted or blown. If the fuse looks fine, check other fuses associated with the fuel system for signs of wear and replace them if necessary.

  • If you need to replace a fuse, be sure to use one with the appropriate amperage rating. Do not install a fuse with an excessive current rating.
  • A blown fuse may mean that the circuit is drawing too much current and you need to check the individual circuits. When checking the relay, have someone start the car for you, or have it checked by a repair shop.

Check fuel pump voltage. The current flowing through the circuit won’t necessarily go to the fuel pump, so you’ll have to check the voltage as well. Read your car’s owner’s manual to find out which part you need to inspect and the correct inspection procedure.

  • Test the voltage source to see if current is flowing to the fuel pump after leaving the fuse.

Perform a voltage drop test with a voltmeter. Make sure the wires have adequate voltage and the ground wire is properly grounded. If the electrical test results show everything is OK, there is likely a problem with the fuel pump and it needs to be replaced. You can perform an additional oil pressure test for a more comprehensive inspection.

  • If the voltage difference exceeds 1 volt, the wires may be corroded or there may be a problem with the positive or negative terminals of the circuit. Take it to a repair shop for more in-depth testing and get further advice.

Perform an Oil Pressure Test

Rule out the possibility of filter failure. A clogged filter with sediment can also cause the car to have difficulty accelerating (even though you suspect the problem is with the fuel pump). Check the short fuel inlet hose and blow air into it to make sure there is not much resistance. Check the filter for debris and replace the filter if necessary.

Purchase a fuel pressure gauge. Fuel pressure gauges are available at most auto parts stores. It’s a good investment and works on most car models. If you don’t want to buy one, you can borrow it from a mechanic or auto shop that allows customers to borrow tools. An oil pressure test only takes a few minutes to complete.

Connect the pressure gauge to the fuel pump assembly. Locate the fuel pump (usually near the carburetor or injector) and locate where the fuel pump connects to the filter housing. There should be a small connector that allows you to connect a pressure gauge.

  • Each pressure gauge may be used slightly differently, and each car’s fuel pump is located differently, so check your car’s owner’s manual for more detailed information.

Have someone help you start the engine while you check the pressure gauge. Let the engine warm up slightly and check the oil pressure while the car runs at idle and rated rpm (check fuel pump specifications). If you don’t know the RPM rating, just crank the engine and see what difference the oil pressure makes. You must replace the fuel pump if the problem is severe and the pressure gauge needle doesn’t move.

  • Oil pressure must meet the specifications listed in the owner’s manual and should increase as the engine runs to a certain level. If the oil pressure does not increase, or the pressure difference between the inlet and outlet exceeds 28 kPa (4 psi), then you need to replace the fuel pump.

Tips

  • Need to replace your fuel pump? A refurbished fuel pump is just as good as a new one and is less expensive. If you’re feeling adventurous, some manufacturers offer kits of parts for rebuilding your fuel pump. You can follow the instructions in the tool kit and use a screwdriver to disassemble the fuel pump and then rebuild it. If you don’t like this idea, ask a service center to help you find and rebuild the fuel pump. It should have at least 3 months warranty.