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How to make sure every fuel pump and fuel module installation or repair is a successful one.

When servicing fuel pumps and fuel modules, it pays to look beyond the basics.

Solid installation and repair skills are essential for any technician who wants to do the job right the first time; however, problems that can crop up when installing fuel pumps and fuel modules aren't always obvious – even for the most experienced technician.

Here are some tips to help ensure that every fuel pump and fuel module installation or repair is a successful one.

1) Inspect the electrical connector for signs of damage.

For a variety of reasons, some vehicles may be prone to electrical connector failures. These failures often can be seen as overheated terminals and wiring, so it's essential to replace the mating vehicle wiring when replacing the fuel module or pump on these vehicles. Otherwise, the new service part can fail prematurely. If a new wiring pigtail is included with the module or fuel pump kit, be sure to install it. The new pigtail may often look different than the original part, but the improved electrical connector can easily be installed by using the parts and following the detailed instructions included in the kit.

2) Examine the fuel tank and fuel module bucket for contamination.

Fuel pump and module failures can often be attributed to contaminants found inside the fuel tank or fuel module. These contaminants can cause excessive wear of the fuel pump, and plug strainer and filters. If contamination is found, the fuel tank should be drained and cleaned before installing the new part. Also, look for rust inside the tank or bucket of the fuel module, which indicates water is in the fuel delivery system. Metal fuel lines and fuel rails should be examined for signs of internal rust or corrosion and replaced as needed. Contaminants can be drawn into a vehicle's fuel system if the evaporative emissions system is not operating properly. It's essential to determine the cause or source of the contamination and correct it before installing the new part.

3) Replace the fuel filter and strainer when installing a new fuel pump or fuel module.

Most fuel module kits include new strainers with the fuel module assembly. If a new strainer is not included with the fuel pump, one should be obtained and installed on the pump prior to installation into the vehicle. Be sure it's correctly seated so contaminants cannot pass around it.

4) Check pressure and flow.

Fuel delivery diagnostics should include the practice of an on-vehicle fuel pressure and flow test. A fuel delivery system must deliver fuel at the required system pressure and also at the proper flow level in order to be fully functional. The first step is to check fuel pressure, but a fuel pressure gauge alone should not be the sole diagnostic tool. To ensure power integrity to the system, electrical circuitry and ground supplies should also be checked. Problems in either area can result in low pressure, causing the pump to run slow.

5) Ask about improper E85 usage.

Although all modern vehicles now run off of fuel that contains some ethanol, E85 is not compatible for the vast majority of today's vehicle market. With prices that are typically lower than gasoline, drivers often fill up on this cheaper alternative without realizing or considering the damage it may do to their vehicle. Essentially all alcohol, E85 is a drying substance and is very hard on fuel pumps and seals when used in vehicles not designed for E85 fuel, and can lead to serious malfunction. Premature failure, fewer MPG and reduced power could be indicators of improper ethanol use, signaling that a repair needs to be done. Be sure to ask the customer with these symptoms if they have recently used E85. Without proper diagnosis, this can result in unnecessary comebacks if the E85 use continues.

6) Check fuel level – and make sure your customer does too.

Most people have driven on empty plenty of times without a second thought. But, driving on "E" can contribute to fuel pump malfunctions. It's your job to make sure your customers know why. Fuel cools the pump motor, so when drivers are running on little to no gas, overheating can result. Besides heat damage, running a vehicle on low fuel causes the pump to pull the dirtiest fuel from the bottom of the tank and possibly cause increased wear. This can destroy or shorten the life of an electric pump. Unfortunately, there are no visual indicators of overheating. A pump in this condition can only be identified by performing an electrical check. It will either be bound, not turning, or show as an open circuit. Overheating will cause it to fail.

7) Check out the vehicle's connection integrity.

An often overlooked measure in fuel pump diagnostics is the electrical connection. Make sure to check the ground wire leading to the fuel module or pump in the tank on the vehicle side and in the harness for a solid connection. Testing the ground for continuity is another step in the process. Another overlooked item: rodent damage. Yes – rodents. Vehicles parked for extended periods of time often fall prey to mice and squirrels that chew on the wiring. A quick inspection can save hours of diagnostic time and trouble.

8) Don't forget fuel pressure and volume testing.

Fuel pressure and volume are considered "known good" values from the perspective of the PCM and are not directly monitored. Typically, fuel delivery problems will not directly set Diagnostic Trouble Codes (DTCs). However, low-pressure or low-volume conditions can cause changes in the operation and performance of the powertrain that may set codes as a symptom of improper fuel delivery. Low fuel pump pressure or volume can cause a lean mixture and fuel starvation at high speeds that may induce lean-related DTCs. Excessive pressure can result in poor fuel economy, rich mixtures and can cause rich-related DTCs to be stored in memory. Fuel delivery testing will ensure that the proper fuel pressure and volume are available under all possible operating conditions.

All fuel delivery test procedures are basically the same. They measure both the pressure and volume of fuel being delivered through the system under standardized testing conditions. In addition to testing for pressure and volume, measuring the amperage of the fuel pump circuit can help determine the cause of a malfunction.

9) Properly diagnosing poor vehicle performance.

When a vehicle exhibits poor performance condition, a dynamic fuel system diagnosis may be needed to determine if the fuel pump is capable of providing sufficient gasoline at the correct pressure. Improper fuel pressure or volume can cause many poor performance complaints.

Performing a dynamic test will provide the technician with the means to measure fuel pressure and delivery to diagnose inadequate pressure and/or volume concerns. Most running tests consist of monitoring fuel pressure while the engine is idling with no load in neutral or park. There may be instances where deficiencies in fuel delivery will not surface when performing pressure testing without the engine being under load. For this reason, it may be necessary (if no problem is found during this no-load testing) to repeat the pressure testing while driving the vehicle under load.

10) Help fix a no-start condition.

If a no-start condition exists, the fuel delivery system should be checked. Prior to performing any no-start fuel system test, verify that there is fuel in the tank and perform a visual check of the fuel system to be sure that the fuel system components are properly positioned and not damaged. Then, follow this checklist to determine if fuel delivery is in fact the culprit: