1997 GMC Yukon fuel preshure

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?

9 Replies

CARADIODOC

MECHANIC
33,873 POSTS

What kind of problem are you trying to solve?

Was this

answer

helpful?

Yes

Saturday, February 14th, 2015 AT 12:22 PM

CELTICWILD

MEMBER
10 POSTS

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.

SPONSORED LINKS

Was this

answer

helpful?

Yes

Saturday, February 14th, 2015 AT 5:44 PM

CARADIODOC

MECHANIC
33,873 POSTS

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.

Was this

answer

helpful?

Yes

Saturday, February 14th, 2015 AT 8:25 PM

CELTICWILD

MEMBER
10 POSTS

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.

Was this

answer

helpful?

Yes

Saturday, February 14th, 2015 AT 8:59 PM

CARADIODOC

MECHANIC
33,873 POSTS

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.

SPONSORED LINKS

Was this

answer

helpful?

Yes

Saturday, February 14th, 2015 AT 9:14 PM

CELTICWILD

MEMBER
10 POSTS

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.

Was this

answer

helpful?

Yes

Saturday, February 14th, 2015 AT 9:42 PM

CARADIODOC

MECHANIC
33,873 POSTS

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.

Was this

answer

helpful?

Yes

Saturday, February 14th, 2015 AT 9:57 PM

CELTICWILD

MEMBER
10 POSTS

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

Was this

answer

helpful?

Yes

Sunday, February 15th, 2015 AT 2:09 AM

CARADIODOC

MECHANIC
33,873 POSTS

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.

Was this

answer

helpful?

Yes

Monday, February 16th, 2015 AT 8:14 AM