Fuel psi less than 50 psi = no start (GM CPI Vortec)

This video covers the basics of fuel pump pressure, current, power and ground testing that can be applied to ANY electric fuel pump. We also go into some unique properties of the GM CPI “poppet” style injection system, and where it differs from typical fuel injection systems. Lower than normal fuel pressure is often misdiagnosed on the central port injection system. For example: Fuel psi at 49 psi during cranking will be a no start! Just about every other fuel injection system will start and run fine with this kind of pressure. But the GM CPI needs a minimum of 50 psi to open the mechanical injector poppet nozzles. This design was used on the 4.3, 5.0 and 5.7 engines throughout the 90s. Engine Performance Diagnostics chapter 16 pages 2 - 6, 9 - 16 Symptoms - intermittent no start condition - starts when a fuel source is used (carb. Clean, starting fluid etc) and may continue to run normally after it starts - possible hesitation/bog on acceleration once running depending on how weak the pump is - fuel system lean trouble codes (P0171, P0174) Fix - fuel pump replacement Tests shown - how to check fuel pressure on a GM CPI system - how to use a GM fuel pump test connector and fused jumper wire to energize a fuel pump - using a low amp probe and scope to check an electric fuel pump - how to check an electric fuel pump power and ground - understanding the impact of a plugged fuel filter on fuel pump current Tools used - fuel pressure gauge - low amp probe - fused jumper wire - lab scope Playlist - (Chapters 14, 15,16) Fuel Delivery and Fuel Pressure Testing https://www.youtube.com/playlist?list=PLAFYVCyenqcrstVqfSc1PCbQ1pebuNIO6 Related videos - GM Fuel Pump Relay Testing https://youtu.be/McnXLcJNVfI - Low Fuel Pressure from a bad fuel pump ground (Ford Ranger) https://youtu.be/rQ7tvIxQSt0 - How to identify and repair a leaking fuel pressure regulator (GM CPI system) part 1 https://youtu.be/09_wQ9yQ85A - How to identify and repair a leaking fuel pressure regulator (GM CPI system) part 2 https://youtu.be/dAAFM3zlJME - Fuel Pump Electrical Circuits Description and Operation https://youtu.be/Rqtfrx-HeD0 - Symptoms and Causes of Low Fuel Pressure (Part 1) https://youtu.be/RyEPOeQB0Zg For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at www.scannerdanner.com as an eBook or paper book. Want even more diagnostic training? Whether you are a DIY trying to fix your own car, someone looking to become an auto technician, or a current auto technician that wants to get more into diagnostics, subscribe to ScannerDanner Premium https://www.scannerdanner.com/join-scannerdanner-premium.html There is a 14 day free trial. On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere! Disclaimer: Due to factors beyond the control of ScannerDanner LLC, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. ScannerDanner LLC assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. ScannerDanner LLC recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of ScannerDanner LLC, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not ScannerDanner LLC.