1997 GMC Yukon fuel preshure

Tiny
CELTICWILD
  • MEMBER
  • 1997 GMC YUKON
  • 5.1L
  • V8
  • 4WD
  • AUTOMATIC
  • 170,000 MILES
I hooked up a fuel pressure gage and turned the key to on. Fuel shoots up to 61psi. Then trying to start it shoots up to 65psi and then back to 61psi when I stop cranking. It holds at 61psi for a few seconds then slowly starts falling but not all the way to zero. Could this be a leak?
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Saturday, February 14th, 2015 AT 12:10 PM

9 Replies

Tiny
CARADIODOC
  • EXPERT
What kind of problem are you trying to solve?
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Saturday, February 14th, 2015 AT 12:22 PM
Tiny
CELTICWILD
  • MEMBER
I am trying to trouble shoot a crank but no start. I have Strong spark. When I spray starting fluid in the carb and it didn't Make a difference But I have spark.
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Saturday, February 14th, 2015 AT 5:44 PM
Tiny
CARADIODOC
  • EXPERT
I suspect the starting fluid isn't getting past the throttle blade.

Also, pull a spark plug out and see if it's wet. If it is, and given the dropping fuel pressure, pull the vacuum hose off the fuel pressure regulator and check if it's wet inside. If it is, the regulator is leaking and must be replaced. Change the oil right away too to get the gas out that will have run down the cylinder walls. Leaking regulators are fairly common on GM trucks.
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Saturday, February 14th, 2015 AT 8:25 PM
Tiny
CELTICWILD
  • MEMBER
I opened the throttle and sprayed fluid in that way. My oil was coffee with creamer looking so I changed the oil and oil filter. The fuel pressure regulator is inside the the intake manifold. I would have to take that off to check. The problem started with a miss fire and I had to change everything spark plug, spark plug wires, distribution cap and rotor, coil, icm, crank shafts position sensor. My water pump was bad so I replaced that as well.
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Saturday, February 14th, 2015 AT 8:59 PM
Tiny
CARADIODOC
  • EXPERT
Pull a spark plug first and see if it's wet. If it is not, don't pursue the regulator. If it is, see if you can follow the vacuum hose and find a place to disconnect it so you can peek inside it.
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Saturday, February 14th, 2015 AT 9:14 PM
Tiny
CELTICWILD
  • MEMBER
I only know of one vacuum hose. It goes from my break cylinder to inside my manifold right behind my spider fuel system wire port.
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Saturday, February 14th, 2015 AT 9:42 PM
Tiny
CARADIODOC
  • EXPERT
What you're looking for a much shorter and smaller in diameter than the hose going to the power brake booster. Look for the vacuum hose routing diagram on the sticker under the hood. That should show the fuel pressure regulator.
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Saturday, February 14th, 2015 AT 9:57 PM
Tiny
CELTICWILD
  • MEMBER
It says from evaporated canister to purge vacuum diagnostic switch then to evap cnstr purge sol vlv. Then on a different hose pcv to and it doesn't have a name but it's external
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Sunday, February 15th, 2015 AT 2:09 AM
Tiny
CARADIODOC
  • EXPERT
I've been trying to find a drawing of the location of the fuel pressure regulator in one of the online service manuals. The best I can come up with is a description that says it is attached to the injector assembly. You might try doing a search for that part to see what it looks like. It is similar to what is used by Chrysler and on other GM models. The nipple comes off to the side of it. That's the hose to remove and check for wetness.
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Monday, February 16th, 2015 AT 8:14 AM

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