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Discussion Starter · #1 ·
HEy all-

I have been having a consistant issue with my truck. After any fill up- Doesn't matter which station (Exxon, BP, Citgo, Sunoco, 711, Sheetz) or if I hang up at the auto stop, overfill, or 7 gallons on a 1/4 tank I WONT START RIGHT. Sorry for caps, but this is annoying. EGR and Vent valve are changed. There's something else. I hear a vacuum leak on the drivers side, but can't find it (dont have access to smoke machine). I used good ole carb cleaner on all connections while running while engine was cold. I hear it. This is driving me nutty. The dealer will charge me a $109 diagnostics fee plus smoke machine fee (150) to find it yet Im on a tight budget...
 

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Do you have a purge valve on the top front of the driver's side valve cover? If so there will be an emissions tube coming up to it from the rear and another off the front to the intake.
 

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Discussion Starter · #3 ·
Yes. I know the line you speak of well. I cant get to the darn connector, as its between the firewall and back of motor. I replaced the purge valve as well. I had to slice the quck connects, (broke em) with rubber hoses. They are holding well.
 

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Discussion Starter · #4 ·
SOB i know the problem! Just hit me like an anvil hitting Willey Coyote. Theres a kink in the hose I replaced from the front of purge valve to the to the piece in front.
 

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So did you check the kinked hose and did you fix it?
 

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Discussion Starter · #6 ·
Ill post once I get it done. I havn't left work yet....
 

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Hurry up! Just do it! LoL
 

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Just quit your job and walk out then fix it. We don't want to wait...

:mrgreen:
 

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^ :lol:

mjc3276 - is it fixed yet?
 

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Discussion Starter · #10 ·
I did adjust it. sorry for the delay. after a good run... 20 miles @75 mph, came to a stop light and she stalled. did it 2 more times.

had to drive 250 miles with an anxious wife. her
sanity was pressing. regardless, after 250 miles @75 mph, the check engine light is still on and she still doesnt like to start after gettin gasses up.
 

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Well damn that sucks.
 

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Discussion Starter · #12 ·
Hell if this helps, I didnt shut her off putting gas in this morning. She stalled again and the idle was very rough. Imma run the codes again and see what comes up.

I just ordered a fog machine to do a home made (redneck) smoke machine. I will find this damn leak. I might need to go n slappaho out of frustration, but it'll be a learning lesson.
 

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After reading through the following description, I wonder if you have a defective fuel tank pressure sensor?

EVAP System Operation

The evaporative emission (EVAP) control system limits fuel vapors from escaping into the atmosphere. Fuel tank vapors are allowed to move from the fuel tank, due to pressure in the tank, through the vapor pipe, into the EVAP canister. Carbon in the canister absorbs and stores the fuel vapors. Excess pressure is vented through the vent line and EVAP vent solenoid valve to the atmosphere. The EVAP canister stores the fuel vapors until the engine is able to use them. At an appropriate time, the control module will command the EVAP purge solenoid valve ON, allowing engine vacuum to be applied to the EVAP canister. With the EVAP vent solenoid valve OFF, fresh air is drawn through the vent solenoid valve and the vent line to the EVAP canister. Fresh air is drawn through the canister, pulling fuel vapors from the carbon. The air/fuel vapor mixture continues through the EVAP purge pipe and EVAP purge solenoid valve into the intake manifold to be consumed during normal combustion. The control module uses several tests to determine if the EVAP system is leaking.

Large Leak Test

This tests for large leaks and restrictions to the purge path in the evaporative emission (EVAP) system. When the enabling criteria has been met, the control module commands the EVAP vent solenoid valve ON and the EVAP purge solenoid valve ON, allowing vacuum into the EVAP system. The control module monitors the fuel tank pressure (FTP) sensor voltage to verify that the system is able to reach a predetermined level of vacuum within a set amount of time.

Small Leak Test

The engine off natural vacuum (EONV) diagnostic is the small-leak detection diagnostic for the evaporative emission (EVAP) system. While previous leak detection methods were performed with the engine running, the EONV diagnostic monitors the EVAP system pressure or vacuum with the ignition OFF. Because of this, it may be normal for the control module to remain active for up to 40 minutes after the ignition is turned OFF. This is important to remember when performing a parasitic draw test on vehicles equipped with EONV.

The EONV utilizes the temperature changes in the fuel tank immediately following a drive cycle to use the naturally occurring vacuum or pressure in the fuel tank. When the vehicle is driven, the temperature rises in the tank. After the vehicle is parked, the temperature in the tank continues to rise for a period of time, then starts to drop. The EONV diagnostic relies on this temperature change and the corresponding pressure change in a sealed system, to determine if an EVAP system leak is present.

The EONV diagnostic is designed to detect leaks as small as 0.51 mm (0.020 in). The diagnostic can determine if a small leak is present based on vacuum or pressure readings in the EVAP system. When the system is sealed, a finite amount of pressure or vacuum will be observed. When a 0.51 mm (0.020 in) leak is present, often little or no pressure or vacuum is observed. If the test reports a failing value, DTC P0442 will set.

Canister Vent Restriction Test

If the evaporative emission (EVAP) vent system is restricted, fuel vapors will not be properly purged from the EVAP canister. The control module tests this by commanding the EVAP purge solenoid valve ON, commanding the EVAP vent solenoid valve OFF, and monitoring the fuel tank pressure (FTP) sensor for an increase in vacuum. If the vacuum increases more than a calibrated value, DTC P0446 will set.

Purge Solenoid Valve Leak Test

If the evaporative emission (EVAP) purge solenoid valve does not seal properly fuel vapors could enter the engine at an undesired time, causing driveability concerns. The control module tests for this by commanding the EVAP purge solenoid valve OFF and the vent solenoid valve ON, sealing the system, and monitors the fuel tank pressure (FTP) for an increase in vacuum. If the control module detects that the EVAP system vacuum increases above a calibrated value, DTC P0496 will set.

Check Gas Cap Message

The control module sends a class 2 message to the driver information center (DIC) illuminating the Check Gas Cap message when a malfunction in the evaporative emission (EVAP) system and a large leak test fails.

EVAP System Components

The evaporative emission (EVAP) system consists of the following components:

EVAP Canister

The canister is filled with carbon pellets used to absorb and store fuel vapors. Fuel vapor is stored in the canister until the control module determines that the vapor can be consumed in the normal combustion process.

EVAP Purge Solenoid Valve

The EVAP purge solenoid valve controls the flow of vapors from the EVAP system to the intake manifold. The purge solenoid valve opens when commanded ON by the control module. This normally closed valve is pulse width modulated (PWM) by the control module to precisely control the flow of fuel vapor to the engine. The valve will also be opened during some portions of the EVAP testing, allowing engine vacuum to enter the EVAP system.

EVAP Vent Solenoid Valve

The EVAP vent solenoid valve controls fresh airflow into the EVAP canister. The valve is normally open. The control module commands the valve ON, closing the valve during some EVAP tests, allowing the system to be tested for leaks.

Fuel Tank Pressure Sensor

The fuel tank pressure (FTP) sensor measures the difference between the pressure or vacuum in the fuel tank and outside air pressure. The control module provides a 5-volt reference and a ground to the FTP sensor. The FTP sensor provides a signal voltage back to the control module that can vary between 0.1-4.9 volts. A high FTP sensor voltage indicates a low fuel tank pressure or vacuum. A low FTP sensor voltage indicates a high fuel tank pressure.
 

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Discussion Starter · #14 ·
Silvery-

(too long to quote)

You may be right. Thats the only thing I havent changed (Fuel tank pressure Sensor).

In regards to the 496 code, I feel the purge solenoid working. It has to be a leak before the solenoid. The only lace I can think of is the "quick" connect between the engine and firewall. Whats the technique to get that thing off? Ive put an hour and half to get it off... I intend to replace the line with 5/16ths heater hose and a good clamp.
 

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Discussion Starter · #15 ·
Which part is right? From Rock Auto http://www.rockauto.com/catalog/raframecatalog.php?ck[ID]=0&ck[idlist]=0&ck[viewcurrency]=USD&ck[PHP_SESSION_ID]=fp2r8l0ag48gaite2sds7dnia2

2010 CHEVROLET SILVERADO 1500 5.3L V8 OHV : Fuel/Air : Fuel Tank Pressure Sensor Price
ACDELCO Part # 13500745 {#2134578} PART OF FUEL LINE
SENSOR,FUEL PRESS CREW CAB
SENSOR,FUEL PRESS EXTENDED CAB
SENSOR,FUEL PRESS REGULAR CAB
Part Image
$22.79

ACDELCO Part # 13502903 Fuel Vapor Pressure
SENSOR,F/TNK PRESS Order Together With SENSOR COVER PN 20893611; EXTENDED CAB
SENSOR,F/TNK PRESS Order Together With SENSOR COVER PN 20893611; CREW CAB
SENSOR,F/TNK PRESS Order Together With SENSOR COVER PN 20893611; REGULAR CAB
Part Image
$36.99
 

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Usually the quick connects have two tabs (on opposite sides) you squeeze together to release or a small tab you pull out slightly on.

If you provide a VIN, I may be able to nail down the correct sensor.
 

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Discussion Starter · #17 ·
silvery 13,

I will PM my VIN to you . thank you very much for your assistance.
 

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You are welcome. Sensor part number is 13502903 and the cover part number is 20893611.
 

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Discussion Starter · #19 ·
I had an opportunity to replace the line. other than having to chase down a rogue clamp, and a a spark plug wire that popped off, it should be better. it idled more smoothly once it was fixed...
 

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Great!
 
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