97 Silverado will not start

97 Silverado 5.7l vortec will not start. 138k miles. It turns over but will not start. Fuel pressure at rhe port under hood is 50 lbs, but drops to 40 while turning over. I do get a good spark, but will not start, just keeps on turning over and over. Tried to prime the pump by leaving the key in the on position and maybe building up pressure to start, but that does not work, What is my next step?? Thanks in advance.

Could it be a plugged cat??

97 Silverado 5.7l vortec will not start. 138k miles. It turns over but will not start. Fuel pressure at rhe port under hood is 50 lbs, but drops to 40 while turning over. I do get a good spark, but will not start, just keeps on turning over and over. Tried to prime the pump by leaving the key in the on position and maybe building up pressure to start, but that does not work, What is my next step?? Thanks in advance.

Could it be a plugged cat??

Fuel pressure is to low.
You need 65 lbs for a cold start or the injectors will not squirt.
Will it fir with a shot of cab cleaner?

Run a fuel pump pressure test.
Or as much as you can with a no strat.

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.

fired up with starting fluid. Changed the pump and we are now running. Thanks, I was hoping on not parting with $250.00 so close to Christmas. Oh well, it beats a car payment. Thanks again.

Oh well, it beats a car payment.
You got that right.:)

You are welcome.
You can not leave home without that proper fuel pressure.
Even after replacing fuel pump the fuel pressure should be tested.
And we hope you used a good Delphi fuel pump.
Aftermarket pumps are junk and do not work good and soon fail.
Thanks for posting back how it went.
Good luck

I did get a delphi pump, I listened to you guys here, frtom previous posts. Thanks again.

Well did that fix it or do you still have problems?

After installing the Delphi pump did you run the fuel pump pressure test and post back pressure readings?