Started no notice it was losing power when accelerating t...


Started no notice it was losing power when accelerating to merge onto highway. Notice this next time I drove it and check [engine](/topics-engine-ford/) light came on. Code reader says it has a P0191 code fuel rail pressure sensor...

Started no notice it was losing power when accelerating to merge onto highway. Notice this next time I drove it and check [engine](/topics-engine-ford/) light came on. Code reader says it has a P0191 code fuel rail pressure sensor. Tried replacing the sensor but it changed nothing. What should I do next? The truck starts every time no issues there. You only notice the issue when trying to pick up speed to merge onto highway for example and/or when climbing a hill. It really lags when climbing a hill. Mechanic's Assistant: Does the light stay on, or does it blink? The engine light? It stays on Mechanic's Assistant: What is the make/model/year of your car? 2009 f250 super duty 5.4 Mechanic's Assistant: Are you fixing your F250 Super Duty yourself? What have you tried so far? Myself I hope tried changing the fuel rail pressure sensor but didn't fix issue Mechanic's Assistant: Anything else you want the Mechanic to know before I connect you? I dont think so

Automotive Expert
Hello and welcome! My name is \*\*\*\*\* \*\*\*\*\* I can assist you with your question. I am a former master tech and I have worked in this field for 20 years. I specialize this type of problem you are experiencing so I am confident I can assist with this issue. I am sorry you are having this issue and I understand this can be frustrating so I will try my best to help. While we are working on this issue together, please allow up to 30 minutes (or more) between replies as I might be online helping other customers or offline spending time with family. Please understand I can only see what is on this page and what you have already shared with me. Please keep in mind, I don’t know the history of the vehicle and I don’t know your mechanical ability, however, I will try my best to help. The phone call prompts are automatic and are coming from the web site, not from me. If you would like to speak on the phone, please request a phone call on your end and I will call you right away. I am going to start by asking some basic questions to get up to caught up to where you are at with this situation so I can assist you in a timely manner. I appreciate your time and patience while we are working together on this issue. My goal is to provide you with a pleasant experience and ensure all of your questions are answered. Please reply back at anytime so I can fully answer or address any questions or concerns you may have. _Please download or save any documents or images I may send you as they will automatically expire after 7 days._ Can I start by getting your first name? Thank you

AmandaWill I hear a notification whenever you respond?
Automotive Expert
Thank you Amanda. Based on my experience this is likely caused by a faulty or a weak fuel pump provider the fuel filter isn't restricted. The computer flags this code because it knows the fuel pressure is an issue.. thus flagging this code. I would be willing to bet if you monitor the fuel pressure with a scan tool or using a gauge, it will be low during when trying to accelerate. It is normal for the actual reading to be about 8 PSI lower than the scan tool reading at idle, but if the vacuum is removed from the Fuel Rail Pressure (FRP) sensor, the readings should be within 2 PSI of each other. Typical fuel pressure readings at idle are 32 PSI actual and 40 PSI on scan data. Fuel pressure should be between 35 and 45 psi when accelerating. If not this would indicate a faulty or weak fuel pump
Automotive Expert
Thank you so much for giving me the opportunity to help you. I really appreciate your patience through this process. My goal is to provide you with excellent service. If you have follow-up questions on this same topic, please use the reply box below. To start a new conversation with me on a new topic, you can [request me here](//www.justanswer.com/car/expert-amedee/). Glad I can help. Please let me know if you have any further questions. Thanks and have a great evening! Best Regards, Amedee

I have a Autel MaxiDiag Elite. Should this scanner be able to preform the pressure tests?
Automotive Expert
Yes it should

Ok thank you!

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