Any GM mechanics?

[Bart2500HD]

The past couple days I noticed that my truck, especially when the engine is cold, does not start right up like usual and it will crank like it isn't getting any gas. Then it will start, but it stumbles a bit before it comes up to idle. Once it gets running it is just fine until I shut it off and restart it. Any ideas? The air intake is not plugged or loose and there isn't a SES light indicating anything is wrong.

[mudbug660]

I'm not a gm mechanic but I would change out the fuel filter if it hasn't been changed in a while. Some seafoam might help also.

[Haulin' 8.1]

The idle air valve is clogged up. Spray it out with throttle body cleaner. Don't use carb cleaner. Brush the throttle bore and plate with a old toothbrush while spray cleaning the whole mess. The Idle air passage is next to the throttle bore, you'll have to take the intake duct loose to access the throttle body.

 

Engines use very little fuel at idle but lots of air. Won't idle = not enough air. Runs good but won't make power after half throttle = not enough fuel.

 

Vernon

[Shaners]

The fuel pressure regulator has been known to cause hard starting...

[bobcat5544]

IN STEAD OF JUST CHANGING OUT PARTS OR CLEANING PART THAT MY CAUSE THIS PROBLEM, LET DO ONE TEST.

 

GET IN YOUR VEH TURN YOUR IGNITION KEY TO THE ON POSISION THEN TO OFF 3 TIMES. ON THE 3RD TIME TO THE ON POSITION TRY TO START THE VEHICLE.

 

LET ME KNOW WHAT IT DOES AND WE WILL GO FROM THERE

[Bart2500HD]

IN STEAD OF JUST CHANGING OUT PARTS OR CLEANING PART THAT MY CAUSE THIS PROBLEM, LET DO ONE TEST.

 

GET IN YOUR VEH TURN YOUR IGNITION KEY TO THE ON POSISION THEN TO OFF 3 TIMES. ON THE 3RD TIME TO THE ON POSITION TRY TO START THE VEHICLE.

 

LET ME KNOW WHAT IT DOES AND WE WILL GO FROM THERE

 

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Okay. I did that and it still does the same thing.

[bobcat5544]

nexted, pull off the plastic cover on the engine. on the drives side of the engine on the fuel rail, pull off the vacuum line to the fuel pressure regulator. look and see if it wet. if not restart your truck and shut it off pull of the vacuum line agian see if it wet. if you find it wet then its your fuel pressure regulator

 

if not,

then restart your truck lrt it sit for about 5 mins go to the pass side of the engine remove the little black cap on the fuel rail and push in the stem on the schader valve (looks like a valve stem for a tire just larger) if fuel trickles or sprays out just a little then you defilently and a fuel pressure regulator problem or the check ball on the fuel pump is bad.

 

if you can get hold of a fuel pressure gauge this would be a great factor in finding out if it really is a fuel system problem

 

let me know

[Bart2500HD]

if not,

then restart your truck lrt it sit for about 5 mins go to the pass side of the engine remove the little black cap on the fuel rail and push in the stem on the schader valve (looks like a valve stem for a tire just larger) if fuel trickles or sprays out just a little then you defilently and a fuel pressure regulator problem or the check ball on the fuel pump is bad.

 

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Do this with the engine running or not? When you press in the stem on the valve, fuel should shoot all over, right? The truck runs just fine once it starts. I have to work the gas pedal a little to get it to start. What should the idle speed be on the tach? It's around 600 right now.

[bobcat5544]

if not,

then restart your truck lrt it sit for about 5 mins go to the pass side of the engine remove the little black cap on the fuel rail and push in the stem on the schader valve (looks like a valve stem for a tire just larger) if fuel trickles or sprays out just a little then you defilently and a fuel pressure regulator problem or the check ball on the fuel pump is bad.

 

<{POST_SNAPBACK}>

 

 

 

 

Do this with the engine running or not? When you press in the stem on the valve, fuel should shoot all over, right? The truck runs just fine once it starts. I have to work the gas pedal a little to get it to start. What should the idle speed be on the tach? It's around 600 right now.

 

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sorry with the engine not running, on the valve stem if fuel shoots all over then that is good, but make sure you wait about 5 min before doing it

[Bart2500HD]

if not,

then restart your truck lrt it sit for about 5 mins go to the pass side of the engine remove the little black cap on the fuel rail and push in the stem on the schader valve (looks like a valve stem for a tire just larger) if fuel trickles or sprays out just a little then you defilently and a fuel pressure regulator problem or the check ball on the fuel pump is bad.

 

<{POST_SNAPBACK}>

 

 

 

 

Do this with the engine running or not? When you press in the stem on the valve, fuel should shoot all over, right? The truck runs just fine once it starts. I have to work the gas pedal a little to get it to start. What should the idle speed be on the tach? It's around 600 right now.

 

<{POST_SNAPBACK}>

 

 

 

\

sorry with the engine not running, on the valve stem if fuel shoots all over then that is good, but make sure you wait about 5 min before doing it

 

<{POST_SNAPBACK}>

 

 

 

 

 

Okay, thanks. I will look at it. So, if there is good fuel pressure there, what next?

[Bart2500HD]

nexted, pull off the plastic cover on the engine. on the drives side of the engine on the fuel rail, pull off the vacuum line to the fuel pressure regulator. look and see if it wet. if not restart your truck and shut it off pull of the vacuum line agian see if it wet. if you find it wet then its your fuel pressure regulator

 

if not,

then restart your truck lrt it sit for about 5 mins go to the pass side of the engine remove the little black cap on the fuel rail and push in the stem on the schader valve (looks like a valve stem for a tire just larger) if fuel trickles or sprays out just a little then you defilently and a fuel pressure regulator problem or the check ball on the fuel pump is bad.

 

if you can get hold of a fuel pressure gauge this would be a great factor in finding out if it really is a fuel system problem

 

let me know

 

<{POST_SNAPBACK}>

 

 

 

1. I took off the vacuum line to the fuel pressure regulator. It was not wet, but a little gas came out of the regulator where the line goes onto.

 

2. I pushed in the pin on the Shrader valve and the gas shoots up and hits the hood.

 

I also inspected the throttle body and it appeared really dirty, so I got a can of throttle body cleaner and sprayed it down until clean. Truck still starts bad and I have to work the gas pedal to get it running. Once I rev it up a little it comes down to about 600 rpm and stays there, but it runs a little rough.

[bobcat5544]

IF GAS CAME OUT OF THE REGULATOR VACUUM PORT THEN THAT IS YOUR PROBLEM. YOU SHOULD NOT HAVE ANY GAS COMING OUT OF THAT VACUUM PORT

[Bart2500HD]

IF GAS CAME OUT OF THE REGULATOR VACUUM PORT THEN THAT IS YOUR PROBLEM. YOU SHOULD NOT HAVE ANY GAS COMING OUT OF THAT VACUUM PORT

 

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New regulator then?

[bobcat5544]

yep

[Bart2500HD]

yep

 

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Just called NAPA, they have one. I'm on my way.