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Lean Fuel Trim Codes: They Can Challenge the Experienced Technician
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By OReilly Auto Parts
Automotive Shock and Strut Overview | What do they do and why are they important?
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By NAPA
You might know how to check the fuel level, but do you know how to check fuel pressure? There’s a handy gauge on the dashboard that tells you how much fuel is in the gas tank, but if that fuel isn’t reaching the engine under enough pressure, a mechanical failure could be brewing. Let’s take a look at the process necessary to check fuel pressure.
What Does Low Fuel Pressure Mean? link hidden, please login to view
If fuel can’t reach the injector with enough force to atomize the fuel, then the engine won’t run right. More often than not low fuel pressure means a
link hidden, please login to view. A bad fuel pump might limp along for a little while, but eventually it won’t build enough pressure to feed the engine. How To Check Fuel Pressure Using A Fuel Pressure Gauge
To check fuel pressure, you will need a
link hidden, please login to view (also called a fuel system pressure tester). Make sure you are working in a well-ventilated area, as some fuel fumes may escape during the procedure. Turn off the engine. Open the hood. Locate the fuel rail. You may need to remove the engine cover for access. Locate the Schrader valve on the fuel rail. This is where the fuel pressure will be tested. Remove the cap from the fuel rail Schrader valve. Attach the fuel pressure tester, making sure the connection is tight. If the fuel pressure tester has a pressure relief hose, route it to a proper container to capture the released fuel. A link hidden, please login to view makes a perfect catch container, and the fuel can then be used later. Turn the ignition switch to “on,” but do not start the engine. The fuel pump will pressurize the fuel system, and you will be able to read the fuel pressure gauge. To test the fuel pressure with the engine running, leave the fuel pressure gauge attached, but place it where it will not contact any of the rotating engine accessories (fan, fan belt, pulleys, etc), and ensure the gauge will not fall due to engine vibration. You may wish to have an assistant hold the fuel pressure gauge.
Start the engine, and observe the fuel pressure gauge. Refer to a link hidden, please login to view for fuel pressure specifications. Once you have taken the fuel pressure reading, shut off the engine. With the pressure relief hose secured to a container, release the fuel pressure from the gauge. Properly dispose of the released fuel or reuse it. Disconnect the fuel pressure gauge from the Schrader valve on the fuel rail. Wipe up any fuel that has spilled, and dry the spill area thoroughly. Place the cap back on the Schrader valve. Replace the engine cover, if it was removed. Close the hood. How To Check Fuel Pressure Using A Diagnostic Tool
Wondering how to check fuel pressure without gauge access? Checking fuel pressure using an OBD diagnostic tool can perform this vehicle test. The exact procedure will vary based on the manufacturer. Refer to the user manual for instructions on how to view live data using the OBD tool.
In the case of the
link hidden, please login to view, start at the Diagnostic Menu and select the “View Data” option. The tool will scan for available parameter identifications (PID) that can be read. Once the tool has read all the PIDs, it will prompt the user to “Select Data to View.” Choose “Entire Data List” for a readout of all the discovered PIDs. In that list should be a line called “FUEL PRES” or a similar term. That diagnostic reading is the current fuel pressure. For those who are more tech savvy, there are smartphone apps that can connect directly to a third-party
link hidden, please login to view. These apps display the real-time information flowing through the onboard diagnostic system. Information like engine temperature, transmission fluid temperature, fuel pressure and oil pressure are commonly available, but will depend on the app. Monitoring Fuel Pressure
If you are the kind of driver who prefers to keep a constant eye on what’s going on under the hood, consider installing a
link hidden, please login to view. There are a wide variety of gauge styles to match your interior, while also delivering needed information. You can keep an eye on fuel pressure, oil pressure, oil temperature and more with an link hidden, please login to view. If you have a performance vehicle or work vehicle, keeping an eye on engine vitals can help stop a problem before it starts. You can use a mechanical gauge attached directly to the fuel system under the hood, or a digital gauge in the cabin that uses a sending unit.
Frequently Asked Questions:
What Are The Symptoms Of Low Fuel Pressure?
Common low fuel pressure symptoms:
Vehicle will not start or keeps stalling Long engine cranking time Hesitation when accelerating Engine is low on power Check engine light is one (engine lean, misfire OBD-II codes stored) What Are Symptoms Of A Bad Fuel Pressure Regulator?
If the fuel pressure readings are erratic or not within the specification, those may be symptoms of a bad
link hidden, please login to view. What Are Symptoms Of A Bad Fuel Pressure Sensor?
If the fuel pressure sensor has gone bad, you may have an illuminated check engine light, trouble getting the engine to start due to low fuel pressure, or reduced engine power.
If your engine isn’t running right or the check engine light is on, then a fuel pressure check can be a good starting point for diagnosis. As you can see, the process is pretty straightforward with the right diagnostic tool. Your
link hidden, please login to view and NAPAonline carry a wide variety of link hidden, please login to view to fit your needs. Don’t feel like leaving the house or don’t have the time? Order on NAPAonline to get
link hidden, please login to view on 160,000+ products. However you choose to shop, make sure to take advantage of link hidden, please login to view to receive 1 Point for every dollar you spend. When you earn 100 Points, you automatically get $5 off your next purchase! Don’t feel like testing fuel pressure yourself or just don’t have time? You can also swing by your local
link hidden, please login to view for a fuel pressure check. Their ASE Certified technicians have the right tools and training to diagnose any fuel related issues that your car, truck or SUV experience. Photo courtesy of
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By NAPA
Brad Sweet and the
link hidden, please login to view No. 49 team of Kasey Kahne Racing ventured to Golden Isles Speedway in Waynesville, Georgia, and were met with a challenging weekend of racing. The Deuces Wild event, which featured both the High Limit Racing series and the Lucas Oil Late Model Series, marked the first-ever 410 sprint car races for the track renowned for late model racing.
On the first night of competition, Sweet started strong with a fifth-place qualifying effort at a time of 12.992 seconds. After a close, nose-to-nose start in his heat race, the NAPA driver challenged for the lead but came up just short, clinching a second-place finish. From there, the Big Cat transferred directly to the evening’s feature. The five-time World of Outlaws champion climbed from eighth to sixth, demonstrating his ability to navigate through a tricky field in dirty air.
The NAPA Auto Parts No. 49 team continued their momentum into the second night of the Deuces Wild, impressing spectators with a fourth-place qualifying run at 13.058 seconds. Sweet held his ground in his heat race, finishing second and securing a solid starting position for the evening’s feature. Despite the intense competition, the NAPA driver showcased his resilience, advancing from seventh to sixth in the main event.
The strong performance at Golden Isles puts Sweet and the NAPA team second in the points standings with 225 points, just 18 points shy of High Limit Racing points leader Tyler Courtney. The Kasey Kahne Racing team will take the month of March off from competition to prepare for the remainder of the season before heading to Arkansas and Texas in April.
Start / Finish:
Thursday, Feb. 22: 8 / 6
Saturday, Feb. 24: 7 / 6
Points Standing / Total: 225 pts. / 2nd (-18)
Next Race: Tuesday, April 9, Riverside International Speedway, West Memphis, Arkansas
How to Watch or Listen:
link hidden, please login to view NAPA:
link hidden, please login to viewBrad Sweet: link hidden, please login to view
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By Counterman
One of the more difficult things about any technology is all the new terms you seem to get hit with, and in the automotive world, CAN bus was one of those terms. The second half, “bus,” was a term we had already used for many years, primarily as “bus bar.” A bus bar was a metal strip or bar that distributed power among multiple components.
In the automotive world, even when fiber-optic turn-signal indicators mounted on the front of a fender were as high-tech as it got, bus bars were inside many components such as fuse panels and relays, and sometimes under the hood for various engine electronics.
Then computer electronics took over. At first, we just had one electronic control unit (ECU) to deal with, and it was for the engine. Before you knew it, there was a transmission control unit, then the ABS control unit (not necessarily in that order). Wiring harnesses got bigger … and bigger and bigger.
Today, a car can have as many as 150 ECUs. In addition to the familiar engine, transmission, brake and airbag control units, doors, seats, mirrors, power steering, audio systems, cruise control, batteries and charging management systems all have their own control units. And as you can imagine, that’s just scratching the surface.
As technology was taking a ride with all these systems, engineers realized there were too many wires and too many sensors. There was no choice but to get aboard the CAN bus. CAN stands for controller area network, and a CAN bus, simply put, is a common communication line that can be used by all ECUs on the network.
The various control units on a modern vehicle need to communicate and share information over this network. Here’s an example of how and why. Years ago, when you turned on the air conditioning, a simple switch sent power to the compressor clutch. Today, the HVAC control module may need to communicate with the body control module (BCM) to notify it that A/C has been requested.
The BCM in turn sends a request to the engine control module (ECM) to “ask permission” if it can energize the A/C-compressor relay. The ECM looks at current engine operating parameters and sends a response signal to the BCM, which, in turn, sends a signal to the A/C relay.
The technological features on today’s cars are nothing short of impressive. Advanced driver-assistance systems (ADAS) include features such as adaptive cruise control, forward collision warnings, high-beam safety, lane-departure warnings, traffic-signal recognition, lane-keep assistance, automatic emergency braking and traction control.
All of the associated control units are in constant communication with each other, and since many of them must utilize information from the same sensors, through the CAN bus network this is possible. Instead of an ambient-temperature sensor for the ECM, the HVAC control unit and the instrument cluster, one sensor can share its data over the network.
Some high-end vehicles have a feature called automatic brake wiping, or brake disc wiping. This feature utilizes information from a rain sensor (also used by automatic windshield wipers) that’s sent over the CAN bus to the ABS control unit. In programmed intervals, the ABS control unit lightly applies the brakes in a manner that the driver won’t notice, to clear water and moisture away from the rotors and provide maximum braking when needed. All of this is only possible thanks to the communication available over the CAN bus.
Developing the CAN bus system was no simple feat, and it took many years to complete. The requirements for automotive CAN bus communication are standardized as part of the OBD II vehicle communication standard. There have been many changes over the years related to CAN communication, primarily affecting the speed and manner in which data is transmitted. The easiest way to think about it is to relate it to the changes over the years in USB design we’re all familiar with. It’s for the same reason. They transmit data quicker.
From a service standpoint, technicians have had to become familiar with CAN bus systems. U-codes that indicate a loss of communication between modules or on a specific bus are a tool designed to help technicians diagnose CAN bus problems.
Electrical wiring diagrams reflect the CAN bus network, and there are three different types of networks – loop, star and loop/star hybrid – referred to as CAN bus topology. Being able to recognize the type of topology can help a technician diagnose CAN bus errors quicker. In today’s world, we all have to get aboard the CAN bus.
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