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Codes P0171 and P0174

Tiny
TERESA BISHOP
  • MEMBER
  • 1997 FORD THUNDERBIRD
  • 4.6L
  • V8
  • RWD
  • AUTOMATIC
  • 275,000 MILES
So we have these codes. We replaced 02 sensors, MAF sensor, used cataclean. Checked EGR and valve. Checked for vacuum leaks. Car runs worse with everything we try. Ready to junk it. What else can it be? If our fuel pressure gauge is working it has 9 psi. It has weak start. When you punch the gas it bogs down. After replacing MAF it quit running three times driving down the road.
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Thursday, September 28th, 2017 AT 9:35 AM

5 Replies

Tiny
STEVE W.
  • MECHANIC
  • 12,950 POSTS
If the fuel pressure gauge is correct your fuel pump is toast. You should have at least 38 psi. Normally you should have 38-45 with the key on engine off.
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Thursday, September 28th, 2017 AT 11:38 AM
Tiny
TERESA BISHOP
  • MEMBER
  • 24 POSTS
It is a new cheap pump got off eBay. Got the MAF and 02 sensors off eBay too.
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Thursday, September 28th, 2017 AT 11:49 AM
Tiny
STEVE W.
  • MECHANIC
  • 12,950 POSTS
If it is showing 9 PSI it is not going to run very well if at all and you will get other codes because it is running very lean.
Try RockAuto. Com. Or your local parts store.
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Thursday, September 28th, 2017 AT 12:17 PM
Tiny
TERESA BISHOP
  • MEMBER
  • 24 POSTS
So now after I drove it a while today I am getting a code for throttle position sensor. Are you saying we're getting false codes?
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Thursday, September 28th, 2017 AT 3:29 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,840 POSTS
Yes, it sounds like you need to replace the fuel pump.

Here is a guide and some diagrams to help you get the job done:

You will need to raise the car up safely to begin.

https://www.2carpros.com/articles/jack-up-and-lift-your-car-safely

and this guide will give you an idea of what you are in for when doing the job.

https://www.2carpros.com/articles/how-to-replace-an-electric-fuel-pump

Diagram (below)

Please let us know what happens and upload pictures or videos of the problem.

Cheers, Ken
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Friday, September 29th, 2017 AT 10:11 AM

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