2000 Chevy Blazer Code P0452

you will need to hook up a smoke machine to find the leak. your local dealer has one they can do it with.

I had a smoke machine hooked up and thats how the leak was found.

when you checked the canister, did you notice a white powder in the lines. if you did you need to replace the canister.

When i checked the canister there was no white powder. but i think i have figured it out. I do not have any voltage at the pressure sensor (key in run position) I tested c3 white plug pin 27 at PCM and have 5 volts so i have a bad wire or connection.
However I did just start having another problem.
With the heat reaching 85 the last 2 days my blazer gets to about a temo of 190 degrees and starts sputtering and stalls (after about 25 min of driving). Can hear fuel pump kick on when i try to start. Will not start bck up untill it cools down. Can drive all day when the temp is below 80 outside and will not have a problem. Tried replacing ignition control module, and coil pack. did not help me at all. Any Ideas?

check and see if your loosing fuel pressure or spark. when it does it try to disconnect the mat sensor and maf sensor and try and start the vehicle. you may need a scan tool to see what the mat (manifold air temp) is reading when it does this.

I finally just recreated the stalling. I tried unpluging the mat and maf sensors and had no luck. I have plenty of spark and i have fuel pressure. however there is alot of air in the fuel line. I do not have any leaks and llike i said i can drive all day long as long as the engine temp is below 190 degrees. It holds pressure in fuel line for about 5 min before it slowly starts to drop. It acts like the fuel is vaporizing in the line when engine gets above 190 degrees. when i release the pressure on the pressure gage the fuel pressure only goes up to 43 lbs untill i let the motor cool for a little bit, then the pressure is 54 lbs. If it was the sending unit i should have the problem all the time not just when i get over 190 degrees. Any ideas i would greatly appreciate it. Thanks.

sounds like you dont have enough fuel volume. the way you can check this is brake torque the vehicle and have someone open the valve on the fuel pressure gauge. if it stall or feel like its gonna die, you need a new fuel pump

Bad fuel pump. I just had the same symptoms on the wifes '02.
This was with a 1 month old pump. You can hear it slow down and the pressure drops once the engine heats up. The problem is low fuel flow. It is causing vapor lock.