fuel Pressure Regulator

[firestomper]

1998 Chevy Burb 5.7 liter eng. multi-port injectors.......When replacing the Fuel Pressure Regulator the instructions mention attaching a vacuum line to the Regulator...But when I lifted the intake manifold off of the old regulator there was no sign of any vacuum line attached to the old regulator. Is there not susposed to be one because its inside the manifold or has my old line evaporated ? Thankyou. I also am replacing this because I am having a problem with vehichle not wanting to start have replaced 3 fuel pumps already and don't think that is the cure... since problem is still occuring. thanks for any input

[MT-2500]

Welcome to AF.
If the fuel pressure regulator is inside the upper intake it does not use a vacuum hose/line.
It gets vacuum from engine vacuum inside intake threw the vent hole made in fuel regulator.

After you get the regulator replaced always run a complete fuel pressure test.
Watch your cold start pressure real close.
You should have 65 lbs of fuel pressure on a cold crank/start.

What brand of fuel pump ar4e you using or did you put in it?

[firestomper]

it was a cheap fuel pump....thinking might have to be getting OEM finding out these cheap ones aren't going to work...
thankyou on the vacuum line was thinking that was true but had to make sure
The only test I did was after start up I got between 55 and 60 PSI at shrader valve.
What would a complete test be ?
Right now I have to get it towed back home since it only lasted about 20 miles before dying last night.

[MT-2500]

On hard to start you need to watch the cold cranking fuel fuel pressure.
You need 64-65 lbs of cold cranking fuel pressure for the injector to squirt fuel on a cold start.
Even a couple of lbs low will give you a hard start.

You are learing the hard way.
Anymore all Cheap pump and aftermarket pumps are junk.
The AC-Delco/Delphi fuel pumps are the only one that will do the job right.

Complete test is.
The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

[firestomper]

thanks for full test procedures....
Burb will be on tow truck coming home soon
But I did throw a gauge on it in parking lot of walgreens and I had no pressure at all with key on or while cranking.
So we are ordering a good fuel pump as I type. then will do the fuel tests. thankyou again

[MT-2500]

You are welcome.
If the pump is bad and it has any warranty see if they will exchange it for a good AC-delco/Delphi fuel pump.
Let us know how it goes.

[777stickman]

Also supply the VIN when you order the new AC pump. I have seen same year, model & engine take different part number pumps. The VIN will get you the right pump.