I'm wondering if the the PCM controls the Fuel Tank Pressure Sensor on a 1997 K1500?
Thanks,
dave w
I'm wondering if the the PCM controls the Fuel Tank Pressure Sensor on a 1997 K1500?
Thanks,
dave w
P0452 Evaporative Emission Control System Pressure Sensor Low Input
P0453 Evaporative Emission Control System Pressure Sensor High Input
Are both listed in 1997 Vortec cal and both unchecked for no reporting.
I think P codes are from PCM, then there's B codes which are Body Control Module, and C codes which are ABS/Suspension... there's a pattern but some codes overlap like these Fuel Sender is in B and Fuel Tank Pressure in B on later vehicles...
Then U codes is missing data stuff.
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
That has me thinking, I need to find the published technical material to figure out if the fuel tank pressure sensor is an input / output to the Evaporative Emission Purge Valve (which is controlled by the PCM). I'm thinking most likely an input, but where? The fuel tank is from a single tank system, so is the fuel tank pressure system used by the fuel pump balance system? The vehicle is a daily driver, that has to pass emissions, so I need to get my homework done correctly.
dave w
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
NM. much better explanation Robert.
Last edited by gregs78cam; 05-26-2013 at 06:27 AM.
1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
1981 Camaro Z-28 Clone, T-Tops, 350/TH350
1981 Camaro Berlinetta, V-6, 3spd
1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s
from a very condensed point of view:
normally, the PCM allows the engine vacuum that would normally draw fumes from the CCP and allow the tank to vent as necessary. it also controls a solenoid that prevents the tank from venting vacuum. so the solenoid is switched when the engine is creating vacuum, causing a vacuum to exist in the tank. the tank pressure/vacuum sensor is read to determine if there is enough vacuum to consider it a pass. this tests a couple of things at once, mostly CCP and fuel tank integrity.
i might be able to grab a better explanation, but that's essentially how it all works.
This is for 1996 and 1997 ONLY!
Evaporative Emission Control System
Purpose
The Evaporative Emission (EVAP) control system limits the fuel vapors from escaping into the atmosphere. The EVAP transfers the fuel vapor from the sealed fuel tank to an activated carbon (charcoal) storage device (EVAP canister). The EVAP canister stores the vapors until the engine is able to use the extra fuel vapor.
When the engine is able to use the extra fuel vapor, the intake air flow purges the fuel vapor from the carbon element, and then the normal combustion process consumes the fuel vapor.
The fuel tank is sealed with a fuel cap that is not normally vented to atmosphere. The fuel tank cap has a safety valve which allows for both pressure and vacuum relief.
Operation
Fuel vapors from the fuel tank purge and flow into the EVAP canister tube labeled Tank and the carbon absorbs the vapors. The canister purges when the engine is able to use extra fuel vapor. A vacuum source is applied to the EVAP canister tube labeled Purge to draw fresh air through the top of the canister. The air mixes with the fuel vapor and the mixture is drawn in the intake manifold to be consumed in the normal combustion process.
While the canister is purging, fresh air is drawn in through the air inlet at the top of the canister. Air flows to the bottom of the canister and forces the vapors out the Purge tube.
The EVAP system in some applications uses an electrically controlled solenoid to cycle the vacuum to the purge canister. The control module cycles the solenoid when the engine coolant temperature is greater than 45°C or the Short Term Fuel Trim counter is less than 122.
A vacuum switch in the purge line detects when the system is purging. The normally closed switch will open when less than 1 inch Hg is present in the purge line.
EVAP Canister Location
The canister is located in the left front fender well.
Last edited by Caleditor; 09-28-2013 at 03:40 AM.
1998 on up use FTP Sensors
Hey Dave I posted the Schematics for you
Thanks, for posting the wiring diagrams! http://www.gearhead-efi.com/Fuel-Inj...9545#post29545
Seems like I can't find the wiring schematic for the Fuel Tank Pressure Sensor show in post #1.
dave w
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