Hard Starting And Sometimes Rough Idle

[grreed]

I need help with a 99 Chevy Silverado 5.4 liter automatic with 140k miles. It is hard starting and sometimes rough at idle. I have replaced the plugs no help. I replaced the fuel filter which helped a little, but still takes 2 cranks of the key. Some time after a start or while sitting at the stop light I can feel the truck idle rough. Does anyone have suggestions?

[atboley]

5.4 liter???? i dont think so... you may have a leaking fuel pressure regulator if it is a 4.3, 5.0, or 5.7, the regulator is under the upper plennum and attatched to the injector assembly... it will leak gas into the intake and cause long cranking and depending on how bad it is leaking will cause a rough idle... check your fuel pressure, if you key up the pressure and with the engine off and it drops right fast(should hold steady and not drop), then you prolly have a leaking regulator or possibly a leaking fuel pump, but because of the rough idle, iwould go with the regulator

[grreed]

Your right about the engine size it is 5.3 my bad.

This fuel pressure regulator, is it a difficult fix? I have replaced the nut kit on a 4.3 vortec which required the tear down of the upper plennum. Is this a simular tear down? I don't have alot of special tools and really don't whant to take the whole intake off.

[Norseman]

Your right about the engine size it is 5.3 my bad.

This fuel pressure regulator, is it a difficult fix? I have replaced the nut kit on a 4.3 vortec which required the tear down of the upper plennum. Is this a simular tear down? I don't have alot of special tools and really don't whant to take the whole intake off.

 

Easy Job.

 

To Remove:

 

Relieve the fuel system pressure. Refer to Fuel Pressure Relief Procedure.

Clean the fuel pressure regulator retainer and the surrounding area.

Remove or disconnect the following:

Fuel pressure regulator vacuum line.

Fuel pressure regulator retainer.

Fuel pressure regulator.

Remove the following parts from the fuel rail:

Backup ring

Regulator Seal O-ring

Regulator filter

Regulator seal O-ring

 

 

To Install:

 

Install the following parts onto the fuel pressure regulator.

Backup ring

Regulator seal O-ring

Regulator filter

Regulator seal O-ring

Lubricate the fuel pressure regulator O-rings with clean oil.

Install the fuel pressure regulator and retainer.

Connect the vacuum line.

Tighten the fuel filler cap.

Use the following to inspect for leaks:

Turn ON the ignition, with the engine OFF, for 2 seconds.

Turn OFF the ignition for 10 seconds.

Turn ON the ignition, with the engine OFF.

[atboley]

on the 5.3 liters the fuel regulator is very easy, and easy to diagnose... it it located on the left side of the engine on the fuel rail with a vacume line comming off of it... all you have to do to diagnose it is start it up for a minute or 2 and let it sit for another minute, disconnect the vacume line comming off the regulator, if fuel commes out of the line when you disconnect it then thats your problem, no gas should come out of the vacume port or the line of the regulator...

[grreed]

on the 5.3 liters the fuel regulator is very easy, and easy to diagnose... it it located on the left side of the engine on the fuel rail with a vacume line comming off of it... all you have to do to diagnose it is start it up for a minute or 2 and let it sit for another minute, disconnect the vacume line comming off the regulator, if fuel commes out of the line when you disconnect it then thats your problem, no gas should come out of the vacume port or the line of the regulator...

 

Well diagnosed. It turn out exactly as you said. Thanks, this should give my starter a rest.

 

Now I have to figure out my turn signal problem.

 

Thanks Again