Dropping fuel pressure and goes into limp mode?

Tiny
BULLITT1939
  • MEMBER
  • 1999 FORD MUSTANG
  • 4.6L
  • V8
  • 2WD
  • MANUAL
  • 20,000 MILES
The car is running about 20-29 lbs of fuel pressure under a load it drops and goes into limp mode. If you stop and restart it resets itself. It’s a 1999 Saleen so basically a supercharged setup. It has two Bosch 130 fuel pumps. Just changed them for new ones today. New fuel filter. New fuel pressure regulator. Traced vacuum lines today and found a few issues. I put new vacuum plugs that were cracked. It was throwing a P0190. I cleared it and haven’t come back. Any help or suggestions would be appreciated.
Sunday, February 5th, 2023 AT 6:10 PM

7 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 50,363 POSTS
It has two Bosch 130 fuel pumps? Is this some kind of race application? If the fuel pump is good then it could be the fuel sock at the pump is clogged or you have a bad fuel pump, it is a deadhead system so there is no regulator which only leaves the fuel pump as being bad. Here is how a stock application is changed out. the video shows how to drain the tank:

https://youtu.be/Q5MH2gnyFH0

Check out the images (below). Let us know what happens and please upload pictures or videos of the problem.
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Monday, February 6th, 2023 AT 11:02 AM
Tiny
BULLITT1939
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  • 37 POSTS
It’s 2 brand new pumps, the same ones that came out of it. New pumps, new socks, fuel filter and fuel pressure regulator. The tank was dropped and cleaned out yesterday. Have the same issue as before all this was changed.
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Monday, February 6th, 2023 AT 11:37 AM
Tiny
KEN L
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  • 50,363 POSTS
Are you sure the gauge is correct? It is a deadhead system so there is not to much to it. Pump and power, can you confirm you have 12 volts to the pump? Here is a guide to help and the fuel pump power wire color (red/blk) so you can do the test.

https://www.2carpros.com/articles/how-to-use-a-voltmeter

If the voltage is low, I would change out the fuel pump control module and check the ground as well. Check out the images (below). Please let us know what you find.
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Tuesday, February 7th, 2023 AT 11:30 AM
Tiny
BULLITT1939
  • MEMBER
  • 37 POSTS
We found the issue. Thanks for the input!
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Sunday, February 26th, 2023 AT 6:11 AM
Tiny
KEN L
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What was it, can you please tell us?
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Monday, February 27th, 2023 AT 8:20 AM
Tiny
BULLITT1939
  • MEMBER
  • 37 POSTS
Well, the car had been modified with a dual set up no longer made. So after initially changing the pumps, we checked all the vacuum lines and found a few issues there. We addressed these, but the car was still not running up to par. We dropped everything again and changed all the old hoses as well as noticed one of the parts was put back incorrectly. It looked like it only fit one way, but you had to route it a different way. We have a collection of Mustangs, but none of them had this set up so it was definitely a learning experience. Glad to report all is well now and we upgraded to larger pumps after dropping it the second time!
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Friday, March 24th, 2023 AT 4:59 PM
Tiny
KEN L
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Glad you could get it fixed, thanks for letting us know. Please use 2CarPros anytime we are here to help.
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Sunday, March 26th, 2023 AT 12:31 PM

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