Ok, I have a 98 Chevy Blazer, 4x4, 4at, 4.3L (W), 181K miles. I have had 3 DTC's for over 2 years, and have had the truck in 2 shops, without correct diagnosis yet! The truck seems to lack power.. it has all the grunt, but almost seems that it's not getting proper fuel..
The DTCs are:
P0440 - EVAP System
P0452 - Fuel Tank Pressure Sensor Circuit LOW Voltage
P0453 - Fuel Tank Pressure Sensor Circuit HIGH Voltage
The fuel pressure was checked with key on, engine off, and was holding within spec. Then with the engine running, it was still within spec. Turned off the engine, remove key, and the system seems to be holding pressure! (left pressure gauge on for 45 minutes after turning off truck) Another shop recommended, and performed a 'smoke test' to check for evap leaks, with NO results. I have been running with these 3 codes for over 2 years.
Furthermore, I notice that when I fill up the tank, within 2-3 drive cycles, the CEL comes on. It will stay on, through continuous drive cycles, till around half tank (or just below).. then the CEL will go off.. It will stay off, until I fill the tank again. Once filled, within 2-3 drive cycles, it comes back on, and there is my vicious cycle!
Besides the normal homework and searching, I have searched THIS forum for 4 hours, and have read through MANY threads! I am still at a loss on this, and am hoping someone can help me! I am not a forum noob, by any means.. I actually admin a local 'all makes/all models' enthusiast forum, and am quite active on 2 others, regarding my Maxima. This Blazer is my daily driver, so it is important to me that I get her fixed right. Any help anyone can offer me will be greatly appreciated! Thanks guys.

 

when you checked fuel pressure did you check fuel volume as well? that check gets overlooked every time

 

The codes you have are emissions related, but won't affect the power of the truck. The PO 452 & 453 tells us either you have a problem with the electrical connector to the fuel tank pressure sensor or the sensor itself is bad. (my vote). PO440 is more of a general code indicating a problem with the evap system. A lack of accurate info from the tank pressure sensor will make that occur.

 

P0440 is the gas cap for sure see that all the time and the other 2 codes are the sensor on the top of the sending unit

 

wish that was the case for me, i got a 440 tried 2 diff gas caps and it kept comming back lol

 

Have you read through these:
P0440 - Evaporative Emission Control System
P0452 - Evaporative Emission Control System Pressure Sensor Low Input
P0453 - Evaporative Emission Control System Pressure Sensor High Input

 

Thanks for the links swart!!! time to do some research.

 

I would look into having the evap canister checked I helped my buddy with a problem similar to this and the canister was at fault but the power problem although was caused by the canister was more complex the charcoal somehow had been forced into the fuel system and clogged the injectors he ended up having to drop the tank to clean it out, unhook all the fuel and vent lines and blow them clean and replace the fuel filter before it quit clogging the injectors with charcoal after he replaced the evap canister

 

Hi Guys,
I know your post are from Dec2009 - but I just got around to getting my 97 Blazer 4.3 up and running. Remanufactored 4.3 and I installed new Spider injector system. I have several issues but am looking into this evap system problem. till need to located the canister in my 2dr 4wd 4.3 Blazer. My big pain the the camshaft postioning sensor error which I will post codes next time around.. But if anyone to point me to the charcol canister and a little help with checking the EGR I would appreciate very much.. Thanks,