Faulty gas cap

[chillfactor]

I know there have been many threads on the stalling problem, I was wondering in anyone checked their gas caps. Let me explain, I was at the gas station today( and this is the second time this happened) and left the Cobra running when I removed the gas cap the idle became rough, and then it kept trying to stall. I turn off the car put cap back on and it ran perfect.....took it back off and the same thing. So I was wondering if maybe the stalling is caused by a bad gas cap.

 

[POISNUS]

It's possible, but I think the problem lies somewhere else. I know that some Ford trucks have a problem with faulty gas caps, they aren't venting properly.

Jason

 

[julio]

If the gas cap was faulty, the check engine light should/will be on when the monitoring test is completed....


P.S. Never fill up with the engine running or take the fuel cap off
while the engine is running, If the computer runs the test, and the cap is off, a code will set and have you at the dealer for nothing, not a big issue while under warrant, but think if you were out of the warranty period and have to pay for the diagnosis....

 

[larryc7777]

I think that the gas caps on all new vehicles are designed to seal completely. The "vent" is routed to the engine by way of the charcoal canister, I think. That's why the car will run rough/die if the cap is removed. Major vacuum leak. So, if the cap were not completely sealing, that would cause a minor vacuum leak. Maybe even enough to cause erratic idle & stalling. So, how do you check the gas cap?

 

[POISNUS]

larryc7777:

Yeah you might be right, I think that is how it works. I know that Power Strokes use vented gas caps, and some were faulty, resulting in poor fuel milage and other minor problems.

Jason

 

[i8u]

Originally posted by julio
If the gas cap was faulty, the check engine light should/will be on when the monitoring test is completed....


:thumbsup:

 

[2003 Cobra]

I have a Stant locking gas cap and have had no problems with the engine running rough or dying. I tried running my car with the gas cap off and my car ran fine. Hmmm???

 

[julio]

I think diesel use a differant set-up on this than the car line.

Your not really creating a vacuum leak (intake manifold vacuum) by taking the fuel cap off while the engine is running, when the computer runs the test, it compares the pressure in the tank to atsmospheric pressure, this is how the computer knows if you have an EVAP leak that will allow raw hydrocarbons into the air

 

[chillfactor]

Ok, so it was worth a look. Well back to the stall and no fix for those who have it.

 

[Bingo13]

Originally posted by chillfactor
Ok, so it was worth a look. Well back to the stall and no fix for those who have it.

My car only stalls when I reach an 1/8th of tank of gas and it will stall/rough idle repeatedly until I fill the tank past 1/4. The service guys witnessed it first hand and said it must be gremlins. It has done this with and without the mods.