2010 chevy silverado 1500 crew cab 4×4
Can't fill gas tank I have changed the canister the purge valve and the evap pressure valve and still very slow when fill tank.
any help is greatly appreciated.

 

you mean purge valve and vent valve?

well that leaves all the connecting hoses as suspects. Usually it's the filler neck vent.

Using a smoke machine for testing would have prevented replacing working parts.

 

Yes the vent valve was bad that's why I just changed all of it

 

my fuel tank (in a vortec gen III 8 cylinder) was getting increasingly harder to to fill when the engine was hot. a mechanic tested the fuel tank pressure sensor signal voltage and found it was badly out of range. (no codes for a bad f t p s ever showed on the obd2 and no MILs on the dash, either . ) replacement of the F T P S cured my fuel tank being hard to fill.

 

I will get a Fuel tank pressure sensor. I have checked all the lines all seem clear.

 

Hi Mike, the f t p s is an integral part OEM located on or near the fuel tank on most vehicles. (chevy 07 3500 had it on top of the tank, had to drop the gas tank to get at it to replace it. the fuel tank is metal. metal expands slightly with increase in temp. air expands much more with increase of temperature. when the air in the fuel tank heats up due to increased temp, (outside temp, or from engine exhaust heat after running at normal engine operating temps) the air pressure inside the tank goes up proportionately to t temperature rise.. (old chemistry : Raoult's law, Pressure x Volume = n R Temperature . n and R are constants you don't have to worry abut. ) the job of the f t p s is to send signals to the engine computer (ECU or PCM) to tell certain valves to open and shut based on air pressure in the tank to relieve the excess air pressure in the tank when temperature increases. . as fuelin the tank gets low, the amount of air increases. if the f t p s is not receiving proper signals , the signal sent to the ecu as to the proper fuel/ air mix to the cylinders can be erroneous. with a 1/4 full tank, after running at highway speeds, it was almost impossible for me to fill the fuel tank. a very smart mechanic measured signal voltage on the f t p s as deficient when I explained that I was having terrible problems filling the fuel tank when tank was near empty. you want to check the signal voltage in the f t p s because serious errors in the signal it sends can result in bad fuel/ air mix being sent by e c u to the injectors. failure of the f t p s to do its proper job and maintain required air pressure in the fuel tank makes it hard for the new gasoline from the pump to get in to the fuel tank. the pump kept shutting off. PS -- the replacement of the f t p s, and replacement of grounds on the engine, both recommended by The mechanic, seems to have largely cured my P0300 'random cylinder misfire.

 

the purpose of the fuel tank pressure sensor is to check that the evap system is sealed and confirm the evap system can draw vapours from the cannister into the engine when purging.

the fuel system is only sealed during evap leak testing. At all other times air can move freely in or out of the tank.

the tank vents out the top of the tank to the charcoal cannister, out the vent valve out the vent valve filter. This vent path must be open or the tank will be hard to fill. It must be open when the fuel pump operates or the tank would implode due to vacuum.

if you don't have any dtc related to the evap system the ftps is working fine. The sensor can't cause a hard to fill concern. All it does is measure pressure/ vacuum.

find the evap cannister...disconnect the hose from the tank that connects to the cannister...do a fuel fill...if it fills normally the line is clogged and this can be anywhere from the cannister to the vent valve filter.

MMJ had a good suggestion to check the filler neck. stuff can build up on vehicles that use an anti siphon valve.

 

I’m in agreement with MMJ and tech2. Tank filling is a matter of proper venting - the FTP is there as a monitor only and has no direct impact on filling the tank.

Try adjusting the position of the fuel nozzle during filling - sometimes the nozzle being all the way into the neck can cause problems - see if inserting it only 1/2 or 2/3 of the way changes anything.

If you didn’t change the fresh air filter with the vent valve, remove it from above the filler neck (inside the bed panel) and clean or replace it.

Verify the hoses are installed correctly on the canister - if the vent valve hose is connected to the tank side of the canister, the flow through the canister is reversed and the charcoal filter may actually be causing the restriction.

Additionally, most filler necks have a plastic tube insert for liquid fuel during filling and the rubber portion of the neck is meant to provide a venting path. If the plastic tube is kinked or damaged, it wouldn’t necessarily be visible from the exterior wall of the neck.

 

ok guys everything has be replaced that has to do with fill the tank the only thing that not been changer is the fuel pump and the gas tank its self...any help will be greatly appreciated

 

list what you have replaced.