Hello Everyone,
I have a question hopefully someone can answer. I have a 99 Chevy Silverado extended cab 4X4 with a 5.3 Liter. I am having trouble with it bogging down and almost stalling just after I start it and only when the temperature is 40 degrees or colder outside. Once it is warmed up it purrs like a kitten. I don't have a check engine light. I have replaced the TPS, the CTS, the fuel filter, Cleaned the Mass airflow sensor, had the injectors cleaned twice. Once by a local shop and then again by the dealer who was trying to troubleshoot the same problem. I told them I had them cleaned but they said they had the ability to do it better. The dealer also updated the computer. I still have the same issue and was hoping someone might have an answer. Thanks in advance.

 

Could be the IAC(idle air control) valve. Its what controls the idle during warm up, engine loads, electrical loads. But it would do it almost all the time so Im thinking maybe check the FPR(fuel pressure regulator), vacum leaks like the small hoses around the intake.

 

I just sold Yukon that was doing that and it was the throttle body. It was really dirty inside. A can of throttle body cleaner and about 10 minutes time and it was smooth again.

 

Well, I finally got it fixed. Let me tell you the process. I changed the TPS, CTS, Cleaned the fuel injection system twice, I changed the intake gaskets and the fuel pressure regulator and after all that I still had the problem. I tested it and had 30 PSI fuel pressure only when it was cold. I finally broke down and replaced the fuel pump and all is well now. It feels like I have more power now and it runs great. I have never had a fuel pump act this way. Usually they hard fail and just die. Anyways I am happy as a clam now that I got my truck back to normal.

 

Ok...Sorry if I posted this in the wrong area, but Im a Newbie with a quick question. Heres the problem When I first start the car in the morning it is very hard to start....Rough Idle/Stalling etc. If I give it gas when starting and keep the RPMs above 2K I can keep it running. This only happens on the first start of the day. Even if its been sitting all day at work, it will start right up. Problem only happens if sitting for 12 hours or more and the weather is a bit cold....There is no other performance problems....Once I get it past the starting/idling problem it runs great.....Any ideas of what is causing this problem???

 

Yours really sounds like the IAC Valve. When it warms up, turn your AC on at idle and see if the RPM's drop and stay down or surge a little.

 

It sounds like its your fuel pressure regulator, and or your fuel pump. When your truck sits the fuel pressure regulator could be leaking fuel into your intake therefore making it hard to start. When it is cold check your fuel pressure with a test gauge and see what it is. It should be around 70 PSI or more. If it is not its most likely your fuel pump.