hard start-summer heat

[nvrsanvr]

1999 Silverado 4.8 4x4 110k miles. I have had this truck for 7 years, it had 90k miles when I got it. truck starts and runs great when outside temperature is cold or cool. when the weather gets warmer you have to crank it for quite some time before it starts, and then it stumbles for a short time, or dies. this truck has done this for 3 years now. no codes. new fuel filter. runs great otherwise.

[Doug_Scott]

Think it through logically. If your truck had a carb, where would you look it if behaved like this? Logically somewhere in the choke system I would think. Something like a choke pull off, or maybe even the tension on the bimetallic spring that applies the choke plate. Too rich in other words.

Now, on a fuel injected engine, what tells the computer it is cold out, and needs richer fuel mixture to start? Some air temp sensor that is not reading air temp correctly would do that. Why not take a look at that sensor? Sorry, I have no idea what that sensor is, or where it is, just saying that is likely the culprit.

[nvrsanvr]

thank you for your reply. the problem is that I understand what you are saying, but I do not know of any sensor either. I haven't driven the truck much in the past, but I am using it daily now. any ideas where to look and test will be greatly appreciated.

[NitroCherokee]

Have it hooked to a scanner that can read engine sensor data. I would almost bet you'll find the coolant temp sensor is reading -40 Fahrenheit. It has 2 temp sensors one for the gauge and one for the PCM. The other would possibly be the mass air flow sensor reading incorrect intake air temp but a little more unlikely. Best bet is to spend the $ to have it diagnosed correctly.

[Doug_Scott]

Something you can also do if you happen to have a android driven tablet is to pick up one of those Bluetooth ODB2 devices that plug into the diagnostic port on the truck, and grab a copy of the Torque app. That will give you all the readings you could want from the PCM. The Bluetooth adaptor is like $10 on ebay if you time it right. Elm327 compatible I think. You could also get the USB version of the same device, for the same price. Have not looked to see if Torque is available for a pc.