2001 jimmy won't start and have codes

[ssg629]

this started after i replaced fuel pump when it quit with aftermarket one ses light came on had code 453 then jimmy quit was only getting 40psi on pump after 5 months place gave me new pump lasted 10 days haven't checked pressure yet but checked codes and getting code 171.code 174 and code 453 cuold these codes be making pump go bad or should i get oem pump like i have seen on other posts

[MT-2500]

Clear codes and see what comes back.
Is it still running on a aftermarket or airtex pump.

Low fuel pressure could give you lean codes.

Run a full fuel pressure test.
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.

[ssg629]

Originally Posted by MT-2500

Clear codes and see what comes back.
Is it still running on a aftermarket or airtex pump.

Low fuel pressure could give you lean codes.

Run a full fuel pressure test.
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.

i just got a gauge to check fuel pressure vehicle won't start but i'm only getting 40 psi aand only leaks down to about 35 in 45 min

[MT-2500]

You can not leave home with 40 lbs.
Do as much of the pump test as you can.
But sounds like you need to pitch the airtex pump in the trask can and get a good Ac-Delco/delphi pump.
Good Luck
MT