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ok so my truck has been givin me problems lately and yeah its not starting as quickly as it use to all the time. it seams like it only happens when i drive it then let it sit for like 10-30 min. im almost thinking an injector is leaking cause morning start is ok. if i leave it there for a long time it will start fine so yeah i dont know what it is.
 

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Fuel pressure regulator, probably. It cranks and cranks but doesn't fire, right? Instead of immediately turning the key to start, turn it to on, listen for the fuel pump and when it stops then crank the engine. If it fires right up then it's fuel system pressure, probably because of the regulator.
 

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the fuel pump could also be going out....Those were my symtoms before it decided to take a crap me...Putting some gauges on it would also help to answer your question also....
 

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The regulator is probably the culprit. Before you throw a regulator on, pull the vacuum line off the regulator while it is running. If you see any fuel in coming out of the regulator or in the line then its bad.
 

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Beatdown Z, I just tried your vacuum line trick, no gas leaked out of mine. However, my system loses all pressure in about a minute or two (I hooked up a fuel pressure gauge and watched it happen).

Still a bad regulator, or should I look elsewhere? If it was leaking out an injector I guess I'd have some smoke on startup, and/or gas in my oil (would it eventually get past the rings, or do they have a gap tight enough to hold gas?). There's no gas smell so it's not leaking out. It's got to be going back through the return.

My truck is a 2002 5.3.
 

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Could be the check valve in the pump. My 4.8l silverado has a bad check valve and it bleeds the pressure down in less than a minute. Actually like a few seconds.
 

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When you watched the pressure bleed off with the gauge, was the vacuum line on or off the regulator?
 

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I've always checked the fuel pres reg with the engine off and usually if they're bad then fuel drips out of the vacuum line. If its been sitting for a while then it probably wont drip becuase all the fuel that was in the vacuum line has dried up. It works best after a drive :imo
 

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The vacuum line was on the regulator.
Do it again with the vacuum line off and put a pair of vice grips on the return line to stop any fuel from flowing. If the pressure drops and gas comes out of the regulator, then it's bad. If the pressure drops and nothing comes out of the regulator, then the checkvalve is stuck open in the pump. Only way to fix checkvalve is a new pump.
 

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Do it again with the vacuum line off and put a pair of vice grips on the return line to stop any fuel from flowing. If the pressure drops and gas comes out of the regulator, then it's bad. If the pressure drops and nothing comes out of the regulator, then the checkvalve is stuck open in the pump. Only way to fix checkvalve is a new pump.
How do I identify the return line? The Haynes manual says specifically NOT to vise-grip it because that will damage it, but it sounds like that's bullshit.

where is the regulator, and where is the vacuum line? mines been having the same issues lately.
Driver's side. Here's a picture with the plastic cover off the engine, but you can see it with the cover on too, at least on my 2002. The regulator is the round thing above my finger and the vacuum line is the thin hard plastic line with the rubber boot plugged into the top of the regulator, that goes zig-zagging up to the rubber boot above plugged into the black plastic round thing.



I'm going to guess that the return line is the vertical metal line coming out of the right-top of the regulator shaped like an upside-down U (and I would pinch it off downstream where it's rubber).
 
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