2011 Ford F-150 purge flow line blocked
05-24-2015, 08:05 PM
#1
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2011 Ford F-150 purge flow line blocked
My husbands 2011 F150 threw a code yesterday, when we took it to AutoZone they Ran it. It came back as blocked purge flow sensor. My husband checked the purge valve and that seems okay. Does anyone know how much it will cost to replace the sensor. Is it something he can do or do we need a mechanic!
05-26-2015, 11:16 AM
#2
LightningRod
Not so fast
[MENTION=209862]Akmals02[/MENTION]
First I would urge your husband to place ZERO credibility in the AutoZone parts person's recommendations as to what parts to replace
. Doing so would likely be as expensive as taking it to a mechanic, plus all his expended labor, frustration and trips BACK to AutoZone for more parts 
.
True, they can, and will, read the codes for free. But write them down and have AutoZone stop there. You did not mention the code(s) and that would be helpful here. There are 'umpteen' codes dealing with the very complex EVAP system on modern vehicles. If these are the only type codes you're getting, it won't hurt to run with them while sorting things out.
The onboard computer runs various tests, some of which take long periods of time or multiple drive cycles to conclude. Very simple, seemingly benign things can cause EVAP system errors. For example: 1) "Overfilling" your tank repeatedly can cause raw gasoline to overflow in the filler neck and get in the vapor lines and the vapor canister, overwhelming the carbon filter. 2) Improper tightening of the gas cap - too loose or too tight - can upset system leak tests.
Your check engine light will automatically turn off if the failed tests later runs successfully. (ie: if you quit overfilling your tank, or tighten the gas cap properly). Or you can reset the CEL yourself by battery disconnect and see if it comes back after doing diagnostic procedures. BUT be aware. It will not be uncommon for it to take several drive cycles (Complete engine warm up after a complete cool down) for the test to be fully completed again by the PCM.
YES your husband can do it -(if he is even marginally mechanical). But get (&post) specific codes and do your homework on the theory of operation of EVAP systems. The following brief description happens to come from a GM system, but it is descriptive and all makes do the same things.
-----------
" 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 to the atmosphere. The EVAP canister stores the fuel vapors until the engine is able to use them. At an appropriate time, the PCM will command the EVAP purge valve open, allowing engine vacuum to be applied to the EVAP canister. With the EVAP vent valve open, fresh air will be drawn through the valve and 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 valve into the intake manifold to be consumed during normal combustion. The EVAP system requires the PCM be able to detect a leak as small as 0.040 inch in the EVAP system. The PCM uses several tests to determine if the EVAP system is leaking."
-----------
Good luck
First I would urge your husband to place ZERO credibility in the AutoZone parts person's recommendations as to what parts to replace
. Doing so would likely be as expensive as taking it to a mechanic, plus all his expended labor, frustration and trips BACK to AutoZone for more parts .True, they can, and will, read the codes for free. But write them down and have AutoZone stop there. You did not mention the code(s) and that would be helpful here. There are 'umpteen' codes dealing with the very complex EVAP system on modern vehicles. If these are the only type codes you're getting, it won't hurt to run with them while sorting things out.
The onboard computer runs various tests, some of which take long periods of time or multiple drive cycles to conclude. Very simple, seemingly benign things can cause EVAP system errors. For example: 1) "Overfilling" your tank repeatedly can cause raw gasoline to overflow in the filler neck and get in the vapor lines and the vapor canister, overwhelming the carbon filter. 2) Improper tightening of the gas cap - too loose or too tight - can upset system leak tests.
Your check engine light will automatically turn off if the failed tests later runs successfully. (ie: if you quit overfilling your tank, or tighten the gas cap properly). Or you can reset the CEL yourself by battery disconnect and see if it comes back after doing diagnostic procedures. BUT be aware. It will not be uncommon for it to take several drive cycles (Complete engine warm up after a complete cool down) for the test to be fully completed again by the PCM.
YES your husband can do it -(if he is even marginally mechanical). But get (&post) specific codes and do your homework on the theory of operation of EVAP systems. The following brief description happens to come from a GM system, but it is descriptive and all makes do the same things.
-----------
" 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 to the atmosphere. The EVAP canister stores the fuel vapors until the engine is able to use them. At an appropriate time, the PCM will command the EVAP purge valve open, allowing engine vacuum to be applied to the EVAP canister. With the EVAP vent valve open, fresh air will be drawn through the valve and 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 valve into the intake manifold to be consumed during normal combustion. The EVAP system requires the PCM be able to detect a leak as small as 0.040 inch in the EVAP system. The PCM uses several tests to determine if the EVAP system is leaking."
-----------
Good luck