July 27, 2010Hey eveyone...I`ve had my share of fuel system problems in the past with other vehicles however I`m kinda stumped this time around and wanted to see your thoughts on the situation. About a week ago I started to recevie a "Tighten Gas Cap" error on my 2007 Classic Silverado with the 5,3L engine. After cleaning the cap and contantly trying to tighten it I decided to purchase a new cap from my local dealership. Well it didn`t fix the problem. The strangest part about this error message is that it flashes up in the message center only within the first 1/4 mile that I drive in the morning (every morning). The message never reappears throughout the remainder of the day no matter how much I drive. It also does not trip a check engine light. Any suggestion on what else to check and maybe even where the pressure sensor is located that checks for pressure in the area of the cap. Thanks for any help you guys can give me. Jay
Forums : Engines-Gasoline : Tighten Gas Cap Error (5658 Views)
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July 27, 2010Maybe you need to reset the PCM to clear any codes that might be stored. It can take up to 500 miles to clear issues by themselves. Pull the neg. side of the battery for 10-15 minutes and see if the message comes back. Steven
July 27, 2010Thanks Steven for the tip....I`ll give it a try however I did check for DTC codes with my DiabloSport Scanner and nothing showed up as an error.
July 27, 2010I`d try and reset the pcm, but if that doesnt work, i dont know what the problem is
July 27, 2010There is a sensor in some gas caps that can cause this if it is dirty or faulty and can affect the O2 sensor. Also the top part of the filler pipe that screws in might need replacing
July 27, 2010Its a valve on the back of the gas tank.It gets dirty and stops working.
July 27, 2010sounds like you have a really small air leak in the fuel system somewhere on 2003 and new chevys the evap system does a test call the engine off natural vacuum test what happens is after you turn off the vehicle the pcm starts the test as the fuel cools down in the tank it creates vacuum in the tank and the pcm starts looking for a certain amount of vacuum after 300 seconds the test is over and to pass the test it needs to hit a minimum of 3.1# of vacuum or higher if it is lower than that it determins there is a leak and sets a code usually the tighten filler cap code it is possable you may have a tiny leak somewhere else in the system like in the rubber of the filler neck or another rubber line
July 28, 2010Taggie...my local dealership mentioned that the fill necks sometime do go bad like you mentioned. I just can`t see how a formed piece like the fill neck could just go bad esprcially on a vehicle like mine with only 35K miles on the clock.
Icboy...this valve you are talking about, is it a vent or what exacly? And is it located on the back side or top of the tank?
Xcutioner...I did not know about the pressure test after the vehicle is shut down. The only thing that kinda goofs this theory is that I run the vehicle several time throughout the day. Back and forth to work, and when I head out for lunch. The only time the "tighten gas cap" error displays in first thing in the morning. Never any other time. I can tell you that just yesterday I did receive a "gross emissions leak" code that tripped the check engine light. However I reset the code and this morning did not come back on.
Thanks again everyone for all the info so far!
July 28, 2010i think there is a valve on the tank. that would cause a lost of pressure. just like a gas cap issue..
July 28, 2010I had some odd ball lights pop on in my dash on an off even check engine an brake lights an when we would hook it up it always come back clean! Dealer changed ingition switch and inst cluster said there is random problems with each item throwing low voltage out causing lights to pop on during a system check upon start up! Not sure if any of these would be tied to your issue just throwing it out there!
July 28, 2010I braught my 07 chevy for the tighten gas cap message so I baught a gas cap but it did not help.I braught it back put it on thier computer and it said it was a valve on the back of the tank.They changed it and it never came on again.
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