Big drop in fuel economy?

Tiny
MIKE BEDIER
  • MEMBER
  • 1989 FORD F-150
  • 5.0L
  • V8
  • 140,000 MILES
My truck listed above Lariat was running fine. Then shut off while driving. The ignition switch went bad according to the mechanic and damaged the fuel sensor, the EFI sensor and blew the fusible link. I had all those replaced it runs but now only gets 10 mpg down from 15 mpg before I had it fixed. What would cause a dramatic drop in fuel economy? It has a miss I can feel as well. Thanks for your help
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Wednesday, December 9th, 2020 AT 3:28 AM

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Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 107,635 POSTS
Hi,

If the fuel pressure is too high or low, it can cause a misfire and affect the fuel mileage. Do me a favor. This truck has an OBD1 computer system. You can retrieve codes without a scan tool. All you will need is a test light.

Here is a link that explains how it is done. Do this and let me know what codes are found.

https://www.2carpros.com/articles/ford-lincoln-mercury-obd1-1995-and-earlier-diagnostic-trouble-code-definition-and-retrieval

Take care,
Joe
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Wednesday, December 9th, 2020 AT 7:29 PM

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