Now what?

No, you need one that attaches to the threaded connector on the cross tube that goes over to the pass side fuel rail. I see you disconnected the vacuum line that goes to the fuel pressure regulator. Is there any gas in that line? There should not be. If there is the regulator is bad.

You need a tester like this:
https://www.summitracing.com/parts/anm-cp7818?rrec=true

[QUOTE="Livebai8, post: 1419627, member: 8619"i pulled the vac hose and it atleast idled...but when I put back on it dies immediatley.[/QUOTE]
Assuming you’re talking about the vacuum hose to the fuel pressure regulator, take the vacuum hose off the regulator side. The regulator can twist without having to take it off, twist it so that the vacuum port goes from straight up, to down as far as you have room. If any gas comes out the vacuum port, even just enough to wet a fingertip, it’s bad

ks03 said:

[QUOTE="Livebai8, post: 1419627, member: 8619"i pulled the vac hose and it atleast idled...but when I put back on it dies immediatley.

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Assuming you’re talking about the vacuum hose to the fuel pressure regulator, take the vacuum hose off the regulator side. The regulator can twist without having to take it off, twist it so that the vacuum port goes from straight up, to down as far as you have room. If any gas comes out the vacuum port, even just enough to wet a fingertip, it’s bad[/QUOTE]Ok...i took the hose off while truck was idling surprisingly and suction was there but did not see any gas or wetness at the regulator tip. Engine bay does not smell gassy either. Now the tube vac hose before I started any of this did smell a bit gassy but not overwhelming. I'll try your Method and see what happens.

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George B said:

No, you need one that attaches to the threaded connector on the cross tube that goes over to the pass side fuel rail. I see you disconnected the vacuum line that goes to the fuel pressure regulator. Is there any gas in that line? There should not be. If there is the regulator is bad.

You need a tester like this:
https://www.summitracing.com/parts/anm-cp7818?rrec=true

Click to expand...

Ok great. I figured I had the wrong one once I got home. Thanks for the link.

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im not overly familiar with the 5.3 so im a little out of my league here but i took a peek on rockauto. i only show a listing for an electronic throttle body but i also show a listing for an idle air control valve. if your only having issues at idle and your truck does have a separate idle air control valve that could also be your problem. you posted it idled if you pulled the vacuum line off the fuel reglator. will it idle if you pull a different similar sized vacuum line off? a sticking iac valve can cause alot of issues with idle as its not letting the correct amount of air bypass the throttle plate. pulling a vacuum line will serve the same purpose as what the iac is supposed to be doing.

Why on earth would you think that the engine needs LESS fuel off idle than at idle? You said it runs like crap at idle but fine off idle. It aint your fuel pressure since you need more fuel delivery off idle and it runs fine off idle.

Does your check engine light emit a bright light from your cluster?
Clear all codes after you read them first.
Its possible youve set codes that are a result of your belt fiasco.
See if any codes come back. May need to do a idle relearn.

rockola1971 said:

Why on earth would you think that the engine needs LESS fuel off idle than at idle? You said it runs like crap at idle but fine off idle. It aint your fuel pressure since you need more fuel delivery off idle and it runs fine off idle.

Does your check engine light emit a bright light from your cluster?
Clear all codes after you read them first.
Its possible youve set codes that are a result of your belt fiasco.
See if any codes come back. May need to do a idle relearn.

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Sorry...i was out of pocket so I couldn't answer. I got belt and everything else replaced and buttoned up...i started the tahoe up and same thing happens...at first a struggling idle at start up like 300-400rpm...then it idled at 500rpm strong...i let her run for about 8-10 minutes so I gave some gas and let off the throttle and engine shut off once it settled. Tried cranking several times after this and it's like it wasnt getting gas...started her up again and gave gas to keep alive...held for about five minutes and slowly let off throttle. Dropped to about 200rpm almost died but crept up to 400 rpm... been at temp and 400 rpm...just gunned again and drops to like 200-300rpmbit slowly crept up to almost 500 rpm. Could fuel filter be an issue? I have no engine light advising of any codes.

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This year I believe still used a throttle cable. You more than likely have a bad/dirty IAC. If your vehicle is drive by wire, disregard.

Livebai8 said:

Ok great. I figured I had the wrong one once I got home. Thanks for the link.

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Click to expand...

Ok...got me the correct fuel pressure tester...first key on pressure was 56 psi and 45psi with engine on...retried a couple of times after and pressure sat at 50 psi with just key on and 42 psi with engine on...it didn't go any lower with engine running. I pulled the vac line off the regulator but no signs of any gas leaking? Could it be the fuel pump?

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Have you checked the fuel pressure regulator line? It will run with it disconnected but you should plug the line you disconnected with something.