2002 chevy 4.8 drive ability issue

[Irish_Alley]

ok so i think its been about since i got my 02 (5 or so years ago) ive had a problem trying to pass someone. if you floored it it would go nowhere fast, rpms would pick up but speed wouldnt. cold starts were an issue also, it would be hard to start cold and would most the times die when, if you started it back up it wouldnt have any issue at all (as far as the start up). idle seamed really low and had a CEL code for a lean condition (number one thing to cause this on these trucks was an intake vacuum leak) PO171 PO174 were the latest might have been more before the intake but after thats all that showed back up. replaced the intake gasket, cleaned the MAF and throttle body seamed to do better but not where it should. it also lacked power just taking off. im certain it had a couple intake leaks before by spraying WD 40 or something (cant remember) on the intake and it changing the RPMs, you can also use water but do it when the engine isnt really hot.

so i just delt with this issue for some time till the other day after driving the truck for an hour+, i shut her down to unload some stuff and she didnt want to start back up. after about 5 minutes it finally started back up and i drove her home shut her down and tried to start it again, she started back up. i went and borrowed a fuel pressure gauge and she was reading 15PSI. Normal PSI on these trucks is 55-60 with the engine off, i had just bought a fuel filter thinking that could be the issue but to me if it was it would be a constant issue not just every now and then. but anyway i replaced it and the PSI jumped to 25 but still had the same issues. kind of stunned the truck will run with PSI in this range we tested the gauge on another truck (5.3) and the gauge works just fine.

so i replaced the fuel pump and its a totally different truck, will burn out and pass people like she has never done before. it didnt take long at all to change the pump as i removed the bed bolts (8x 18mm or 6 if the last person was lazy when they changed them) and the fuel nozzle bolts (3x 7mm) and a lift really helps to lift the bed off.

just wanted to share this with you guys as i feel like i really did something special since it had whooped my butt for the past few years. i think i did put a pressure tester on it years ago but i dont think it was below tolerance

[bd]

Does that application use a fuel return line to the tank?

[Irish_Alley]

yes. i pinched it off thinking the pressure reg could be faulty but the pressure didnt change. and also kept the gauge on to check for leak down and nothing changed so i think that eliminated the check valve

[bd]

Change the fuel filter on a regular maintenance schedule or you may experience shortened fuel pump life and another failure.  A plugged fuel filter in a fuel return type system places undue stress on the electric fuel pump through overheating and cavitation.

[Irish_Alley]

i can see this as an issue, so what do you think once a year if its a DD?

[bd]

Depends on the fuel supplier (quality of delivered fuel) and the micron sieve of the filter.  Injection filters generally present finer filtration than filters used for carburetion.  With regard to TBI, silty sedimentation accumulating in underground storage tanks can force replacement at 7,000-mile intervals.  As a starting point use the service interval recommended by the factory and then migrate to greater frequency if necessary.

[Irish_Alley]

hey BD maybe you can help out. thought the truck was 100% better, today the wife shut it off and went to start it back up and it just turns, after awhile it started back up. i know first thing would be to check the fuel pressure but i think its going to be an intermittent problem. so for the time being i dont know where to start

[Irish_Alley]

also no cel yet. and dont know exactly what its doing right now but if it was anything like before it would just turn and sometimes stumble then stall. even if you had it floored or feathered the throttle it would only hit and miss then stall. even when it you floor it you can keep it running for a while but only on a few cylinders and as soon as you let off the gas it stalls. then it may start back up like nothing ever happened.

so it will get better each time you try and start it just might take a few minutes before it gets going and it doesnt seam to affect it if you "key on" "key off" "key on" "key off" to build pressure

and it has only done this when warm (but again its only done it 3 times)
one more thing the idle is still low (about 500)

[Irish_Alley]

Got home a little while ago got in the 02 started right up. Added some fuel cleaner and drove around the block about 5 minutes in the country. Went to floor it and she took right off but the battery light came on for a couple seconds I had enough time to look at the volt meter on the dash and she was around 14 where it should be. Then about a second later the battery light went off.

Got home with no other issues, parked it and turn it off. Went to start it and it started for not a full second and died. Went to do it again but when I had the key "on" all the lights I. The dash and radio and head light controls flickered on and off each time I could hear a relay click under the dash somewhere then the issue went away and the truck started right up

[Irish_Alley]

For grins I'll swap fuel pump relays

[Irish_Alley]

well today the problem got a lot worse. i went to start it up and got nothing, no power to dash, starter, radio, horn and maybe light the only thing i got power to that i noticed was the cig lighter (cell phone charger LED was lit up). went inside thinking even if the battery was dead the dome light should of lit up a little. talked to the wife to see who drove the truck last and went back out to it and she started right up.

really low idle (200-300) and even stalls out when you put it in gear due to the low idle. its raining so i wanted to get it into the garage at my place so i had to convince it to stay running by keeping on the throttle when i came to a stop. it seamed to get better with time by time i got to my house (about 10 minutes) it was running much better idle was around the 600 mark (low but normal for the truck). im going to try to check some grounds and see what i find

[roundhouse]

Check all the ground wires and straps everywhere

Will be several from the battery to the engine block and to the body nd to the frame

Remove them and clean the terminals and bolts good

[VileZambonie]

You need to check your charging system output. If it is low or high, you will exhibit these problems. Start there and also scan for DTC's. Do you have a scan tool? Can you look at datastream?

PS: Seem not Seam

[Irish_Alley]

Yes got a scan tool and can look at live data on it.

The alternator is new within a few months (doesn't mean anything) but right before I changed fuel pumps the battery went dead without warning. Put it on the charger and it didn't take a charge. With the engine running it puts out 14 volts put a battery jumper on the truck and she started up but the alternator let out a steam for a few seconds then stopped. Figured it was due to a high draw on the alternator but haven't really heard it again since. Put another battery in it and it's keeping it's charge the old battery wouldn't even charge if it was disconnected from the truck. The whole time the battery gauge is a little above 14. But like I said before the battery light came on even with the gauge reading 14

PS thank you for the clarification on seems

[Irish_Alley]

One more thing while it fresh on my memory, the radios clock gets reset each time the truck acts up.