Low Fuel Pressure from a bad fuel pump ground (Ford Ranger)

1999 Ford Ranger with low power and lean exhaust codes (P0171 and P0174)
This was one of the most bizarre customer complaints I have had in my 20+ years as a mechanic. The complaint was low power but only with the headlights on! To be honest, I thought the guy was on something and I totally disregarded his complaint. I thought to myself "there is no way turning your headlights on can be associated with a low power complaint", I think I even told him that. But this one humbled me for sure and the take away is we need to pay more attention to our customers regardless of how strange of a complaint they may have.

Engine Performance Diagnostics chapter 16

Symptoms
- intermittent low power
- low fuel pressure with the parking lights/headlights on
- low fuel pressure with the turn signals on
- check engine light (P0171, P0174 trouble codes)

Fix
- repair corroded main ground connection for the rear of the truck
(fuel pump, tail lights, turn signals all share this ground)

Tests shown
- how to test fuel pressure
- how to test a fuel pump power and ground
- how to perform a loaded circuit voltage drop test on a ground circuit
- how to use fuel trim data to determine type of lean condition
- what the BARO HZ data parameter tell us about the condition of the MAF sensor
- how to find an open or high resistance in a circuit
- how to read a ground circuit wiring diagram

Tools used
- S.U.R. & R FPT22 Deluxe Fuel Injection Pressure Tester Kit
https://www.jbtoolsales.com/s-u-r-r-f...
- Autel MaxiSYS MS908 Diagnostic System with Wireless VCI
https://www.aeswave.com/cart.php?m=af...
- Deluxe DMM w/Amp Shutters (AES# esi-582)
https://www.aeswave.com/cart.php?m=af...
- heat shrink style wire connector
- AES' Electronics Accupuncture Probes https://www.aeswave.com/cart.php?m=af...

Playlist
- (Chapters 14, 15,16) Fuel Delivery and Fuel Pressure Testing
   • (Chapters 14, 15,16) Fuel Delivery an...  

Related videos
- Fuel Pump Relay Problem
   • Fuel Pump Relay Problem  
- MAF sensor trouble code (P0102) caused by a bad ground (GM 3100)    • MAF sensor trouble code (P0102) cause...  
- Poor running, flashing CEL, no codes (bad computer ground) - Toyota    • Poor running, flashing CEL, no codes ...  
- How to test fuel pressure, injector pulse and spark with basic tools    • How to test fuel pressure, injector p...  

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.
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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.