High Fuel Pressure around 78 PSI?

Tiny
JOE1953
  • MEMBER
  • 1998 CHEVROLET LUMINA
  • 3.1L
  • V6
  • 2WD
  • AUTOMATIC
  • 147,000 MILES
I replace the fuel pump assembly, and after I replace it I check for fuel pressure when I turn the key to on my fuel pressure gauge goes up to around 78 psi and it drops back down to 0 in less than 10 minutes. I believe I may have connect the three line wrong that run from the gas tank back toward the engine I know one of the line is the fuel supply line and one is the return line and I think one is a vapor line I'm not sure about that but one of line want connect up why?
Sunday, December 8th, 2024 AT 4:53 PM

5 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,144 POSTS
Here are the fuel lines as they connect to the gas tank. But to me it sounds like the fuel pressure regulator is stuck, please go over these diagrams to help you. Check out the images (below). Please let us know what happens.
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Monday, December 9th, 2024 AT 9:01 AM
Tiny
JOE1953
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What is the name of the three line? Do they suppose to be the same size? One of the line want connect. The fuel pump and fuel filter is new.
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Monday, December 9th, 2024 AT 3:26 PM
Tiny
KEN L
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They don't name the lines they just show the configuration. Usually for high pressure problems it will be the regulator FYI.
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Tuesday, December 10th, 2024 AT 10:06 AM
Tiny
JOE1953
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  • 793 POSTS
The regulator is causing high fuel pressure on my tester and for the gauge to drop to 0 key on engine off?
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Tuesday, December 10th, 2024 AT 10:41 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,144 POSTS
Most pump will drop to 0 after a little while, how fast does it drop to 0?
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Wednesday, December 11th, 2024 AT 9:55 AM

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