97 GMC Sierra 5.7L. Crank, no start.

My Fiancé's son calls me and says truck quit while driving down the road and now will not start. I go to where the truck is and drag it home.

This truck had gotten a new Delphi fuel pump about two years and about 11,000 miles ago. I test for fuel pressure and it's 0. Won't even move the needle even though there is fuel at the shrader valve.

I switch the fuel pump relay out with the one in my 98 Chevy Silverado with the same engine and that does not make a difference. I can't hear the pump prime because of the buzzer when you turn the key on so I wait until my fiancé gets home so she can turn the key on while I get under the truck. I can hear the pump run but it's not very loud.

Tomorrow I'm going to jump pins 30 and 87 in the fuse box where the relay goes and take an amperage reading to see what I get. I saw Paul do this test on a 97 chevy truck to see if the power and grounds at the pump were good so that he didn't have to try and access the connector at the fuel pump which is very hard to get to on this truck.

What else could be causing this symptom? Fuel pressure regulator? How do I test the fuel pressure regulator? Thanks for any other ideas. I don't have a wiring diagram for this truck so I don't know if there is any other electrical stuff in this system. All the fuses in both fuse boxes looked good.

I just want to make sure that I rule out everything else before replacing the pump again.

I did put my scanner on the truck but no current or pending codes in the ECM.

If you can hear the pump run but pressure doesn't build, it may need another pump. Debris in the tank is the most common cause for repeat pump failure, although I've had more than one parts store fuel pump come back this year...
Been a while since I worked on a 97, but I think it still has an inline fuel filter. Probably not a bad idea to change it as that will get clogged and cause low fuel pressure. I never bother testing pressure before the filter and after it to see if it's clogged. It's a maintenance item, an if I have to touch it, it's getting a new one.
Also there's a ground on the frame not far from the tank that is pretty well known for taking down the fuel pump.
You can put a test light on B+, to pin 87 of the pump relay slot in the fuse box. If it lights then the circuit to the the pump, the pump windings and the ground are intact.
Happy hunting!

Thanks for the reply. The fuel filter was replaced when the new pump was installed, and I also made sure to clean the ground area on the frame and eyelet very good after the new pump was installed. We pulled the bed when changing the pump the last time so I had access to everything.

Truck has 73,000 original miles so I'm not sure how dirty the inside of the tank is but I guess it could be an issue because of the age of the truck.

Here is an update. I tried the test you suggested and the test light did not light up. I went back to the back of the truck and I could see the ground wire mounted on the frame. I used my Innova power probe and I had a ground at the eyelet but could never get a reading on the bolt itself so I took it off and cleaned everything and put it back on and still never got a reading or beep on the bolt itself.

I also tried the test that I mentioned with the amp clamp and got no amp readings. I used my factory service manual for my 98 Chevy truck and looked at the wiring diagram for the fuel system electrical and hot all the time power is supplied at pin 87 which I verified. I also verified that I had a ground on pin 86. I had power at pins 85 and 30 when I turned the key on for the two second prime and then my test light went out like it should.

So right now I'm still not sure if I have a good ground at the pump. I had someone listen under the truck when I turned the key on and he could hear the pump come on and prime. The battery was getting weak so it's now on a charger.

That vortec has the oil pressure sending unit tied in the fuel pump power circuit, it's right behind the distributor, bad, weak connection there?

My factory service manual for the 98 Chevy does not show this oil pressure switch in the circuit though my generic Chilton's manual does. I will look for it today and see if I can see if there is any wiring damage or not. Thanks.

The oil pressure switch in that circuit will not stop the fuel pump.
There's some Scanner Danner videos on YouTube that demonstrate the purpose of that circuit.
In any case, if the pump runs but does not build pressure, then you know it's getting power and ground. You did your due diligence and changed the filter and cleaned the ground. It really can't be anything but the pump as I see it right now. Obviously, load check the power and ground when the tank comes out, make sure there's not a bunch of crap in the tank and install a quality part.

Jumper pins 30 and 87 at the relay socket. Then check for battery voltage at the pump's power feed and for close to 0 volts on the pumps ground wire. Two test points and you're done.

If you have to change the pump: instead of dropping the tank or taking off the bed often times it's enough to just loosen the bed on one side and unscrew it on he other. Then you'll be able to lift/tilt the bed enough to get to the pump without pulling the entire bed. This will not allow to cleanp the tank properly though

As Noah already said, the oil pressure switch will not prevent the pump from working: it only acts as a backup to bring power to the pump in case the relay goes south. In that case it will take extended crank to build up oil pressure which makes the contacts close.

I understand the fuel filter is in there for 2 years. If so, change it anyway

Here is the part that I'm confused about. If I turn the key on, you can hear the pump come on if you are under the truck.

When I jumper pins 87 and 30 at the relay and go under the truck, the pump is not on. Why would the pump work during the prime but not when I jumper the two pins together?

This relay has a pin 87a which according to my wiring diagram, goes to the fuel pump prime connector. Is this why I'm hearing the pump prime when turning on the key but nothing when jumping 30 and 87?

Ok, I was wrong about the sound that I heard when you first turned on the key. It was not coming from underneath the truck but on top of the engine. It only last for about 2 seconds so I'm not sure what is turning on. Sounds like the sound is coming from the passenger side top of the engine.

Ale sure there is a constant power present at the fuel pump relay socket. If not check the ecm fuse #8.

Measure resistance between the feed terminal 87 or 87a in the relay socket and ground. If it's infinite you got an open if it's close to 0 there may be a short to ground. Typically it should be 2 ohms , give or take .5 ohms.

If in specs you may want to use a fused jumper wire and feed the pump directly with voltage into the relay socket, could be pin 87 or 87a, doesn't matter.

I checked power and grounds to the pump with pins 87 and 30 jumped and they were both good. I ordered a new pump. Luckily the one in the truck has a lifetime warranty because the pump price more than doubled from two years ago.

Thanks for all of the help.

Does fuel spit out of the Shraeder valve like you would expect? Several years ago I worked on a truck that for whatever reason I had to remove the stem in the valve and then hook up the gauge to get a reading. Don't remember if I solved that stem issue, but apparently the gauge was not pushing on the stem well enough.

EDIT: I also had to get around the stem in the gauge also. Don't remember if I disconnected that portion from gauge, used an adapter, or pulled that stem also. Just know I had to have no obstruction between the Schrader valve and the gauge head to get a reading.

No, the fuel just kind of dribbled out. I have used this same gauge on this truck before with no issues. We just got done removing the pump and the new one will be coming soon so hopefully it will be fixed.

Update. Installed new pump and fuel filter and now it runs. I want to thank everyone who provided information.

Good news then, thank you for the update .

Glad it worked out for you! Thanks for posting the fix.
I wish I could loosen truck beds to change fuel pumps!
New England road salt has taken that option off the table unfortunately, lol

We did remove the bolts to the bed and slid it backwards to access the tank. That is how we did it two years ago as well.

They do salt the roads here in MO but this truck only has 73,000 original miles and isn't used on the roads that often in the winter when the roads are salted. It's mostly used as a farm truck. The bolts came out fairly easy luckily.

Thanks again for all of the help.