Need help!! 99 tahoe sputters and bogs

[C6Chris]

HI,
I just start to have this problem with my 1999 4wd tahoe 5.7.
After driving it fot about 15 min it starts to sputter, and bog and gets worst to almost stall. If I get off the gas and idle, it idels fine. Once I shut the truck off and let it sit for a little and start it back up it will run till i drive it for a while then starts bogging and sputtering again. Almost like when it starts warming up or something. this just started doing this but does not do it all the time.
I have done plugs , wire, cap, rotor,coil,fuel filter 2 months ago. I also did a fuel sending unit 8 months ago. Cleaned the mass air flow sensor, and EGR valve. this problem started about 4 weeks ago and is sarting to get a little worse every time.

I'm thinking my sending unit(fuel pump) is going bad again.
I have not checked the fuel pressure yet.
thanks for any help

PROBLEM has been fixed, it was my fuel pump!!!
Thanks to all!!!!!!

[horse482]

Welcome to AF. Start with checking the fuel pressure. If all is good there, then I would start to look at the cat. Hope this helps.

[C6Chris]

Thanks for a reply, I'm having a buddy check it today as I type.

[car gal]

It may be your fuel pump.

[C6Chris]

thanks, that is what I was thinking that it was that. One guy told me it might be the Mass air flow???? I'm not sure how to test that though!!!

[surfnobc2]

hey i have the same problem !!! 99 tahoe 2dr 350 runs great until it heats up and not everytime but most it seems like its harder for it to switch gears ! really annoying .... it bogs and ive changed cap rotor plugs wires ,, my fuel pump is really loud but i was told that some are i dont know about my cats but i need help ... it runs alot worse to when the air is on ???? HELP!!!!

[MT-2500]

Originally Posted by C6Chris

thanks, that is what I was thinking that it was that. One guy told me it might be the Mass air flow???? I'm not sure how to test that though!!!

Proper testing is in order.
Fuel pressure and good spark when it acts up.
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.
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.
Post-back fuel pressure readings.
MT

[C6Chris]

HI,
The fuel pressure was tested and it was 56 cold and 54 warm.

[MT-2500]

Originally Posted by C6Chris

HI,
The fuel pressure was tested and it was 56 cold and 54 warm.

Your fuel pressure is about 10 lbs low.
It needs full fuel pressure to run right or start good.

Check fuel filter and fuel pressure regulator and direct fuel pump pressure.
Good luck
MT

[C6Chris]

Hi,
Fuel filter was replaced about 2 months ago. It still started fine with no problems there. I did the Fuel pump Friday night and drove the truck for about 20 min. then drove it sat a little and then Sunday a little. The problem has not returned and hopefully it doesn't. Truck runs strong and is peppy like it should be. I'll post back in a couple of days and let you know if that took care of the problem. I'm hoping and thinking that was it. Thanks again for everyones help.
Chris

[MT-2500]

Good Luck.
MT

[surfnobc2]

im having the same problem ... got pressure tested tuesday ... warm start is 58 running is 55 ... i guess thats low since i hear everyone saying it needs to be 60 - 65 ... and my fuel gauge in my tahoe ... is going nuts its spastic ... it has been for awhile ... and ive changed everything but the fuel pump ... and the cats ... sooo i hope someone can help ... any suggestions anyone ...

[MT-2500]

Originally Posted by surfnobc2

im having the same problem ... got pressure tested tuesday ... warm start is 58 running is 55 ... i guess thats low since i hear everyone saying it needs to be 60 - 65 ... and my fuel gauge in my tahoe ... is going nuts its spastic ... it has been for awhile ... and ive changed everything but the fuel pump ... and the cats ... sooo i hope someone can help ... any suggestions anyone ...

To better help you.
You need to start a new post and give year and engine and tell what it is doing or not doing.
MT

[CaribbeanHigh]

Originally Posted by C6Chris

HI,
I just start to have this problem with my 1999 4wd tahoe 5.7.
After driving it fot about 15 min it starts to sputter, and bog and gets worst to almost stall. If I get off the gas and idle, it idels fine. Once I shut the truck off and let it sit for a little and start it back up it will run till i drive it for a while then starts bogging and sputtering again. Almost like when it starts warming up or something. this just started doing this but does not do it all the time.
I have done plugs , wire, cap, rotor,coil,fuel filter 2 months ago. I also did a fuel sending unit 8 months ago. Cleaned the mass air flow sensor, and EGR valve. this problem started about 4 weeks ago and is sarting to get a little worse every time.

I'm thinking my sending unit(fuel pump) is going bad again.
I have not checked the fuel pressure yet.
thanks for any help

My 99 Tahoe did the same thing, I originally thought it was the fuel filter blocking fuel flow, changed it and it was fine, but then it started happening again, just as you described bogging down then other times being fine. Eventually it stalled in the middle of rush hour and would not restart. Had the fuel pump replaced and that was the fix. 30000+ miles later problem has not returned.

[mmoss10]

When you changed the fuel pump, did you change the whole cartridge? Or just the pump itself? Just curious.