Gas Cap

[Bronco_Huey]

I have a gas cap that is obviously not the right one, it just slides right off. My question is how does this affect perfomance or what effect does it have when the cap is not sealed. I know newer cars will have the check engine light come on if the gas cap is not sealing etc. Why?

Teacher said there is no such thing as a stupid question :-B So dont flame me!

 

[bluesman17]

The only thing i can think of is maybe make the fuel pump work harder because of less pressurization and possibly more contaminants getting in.

 

[Shadow_D]

Teacher said there is no such thing as a stupid question :-B So dont flame me!

The only dumb question is the one that isn't asked.

With the fuel cap on and sealed on newer cars and trucks it creates a vacuum in the tank that the computer reads and fuel pump needs. It should be sealed on your truck because there are fumes that will escape from the tank. These fumes are extremely flammable Any spark (even a cigarette from a passing motorist) will most likely ignite them causing your truck to burn up.

I transport gasoline for a living and being a past firefighter I know the outcome of this type of situation.

I suggest you get to your local auto parts store and get the correct cap for your truck.

 

[STLKIKN]

Older vehicles had vented gas caps to allow the release of fuel vapors to the atmosphere when the fuel tanks warmed up. These vehicles had fuel tanks that could be filled to their capacity right up to the gas cap!

All new(er) vehicles have a vapor recovery system (charcoal cannister) included in their emissions systems. These vehicles have non vented caps and an expansion area in the tank that allows for storage of fuel vapors. (you know how when the gas pump shuts off and you can add five or ten dollars more fuel.... thats the expansion area being filled)

Some of the newer vehicles even have a vacuum system that turns on when the gas cap is removed from the vehicle. (such as when re fueling)
Newer systems will set a code and then turn on the check engine light if the gas cap is left off.
20% of all automobile emissions (pollution) come from un burned hydro carbons (fuel vapors),
the newer systems are designed to limit the amount of those hydrocarbons that are released to the atmosphere.

 

[Bronco_Huey]

Teacher said there is no such thing as a stupid question :-B So dont flame me!

The only dumb question is the one that isn't asked.

With the fuel cap on and sealed on newer cars and trucks it creates a vacuum in the tank that the computer reads and fuel pump needs. It should be sealed on your truck because there are fumes that will escape from the tank. These fumes are extremely flammable Any spark (even a cigarette from a passing motorist) will most likely ignite them causing your truck to burn up.

I transport gasoline for a living and being a past firefighter I know the outcome of this type of situation.

I suggest you get to your local auto parts store and get the correct cap for your truck.

Already picked up the gas cap after I made the post >-


Good information from everyone on this since I really had no idea how/why the engine light on newer vehicles would go on/purpose etc. The engine light didn't come on in mine but it bugged me more then anything that a $6 gas cap wasn't purchased by the previous owner to make the rig less ghetto. They spent $2200 for a rebuilt tranny, had a mechanic change the serpentine belt, but the gas cap was just not a necessity I suppose <_<

Thanks for the info!

 

[Desert Donk]

Here in AZ, at least in the Phx area where annual emissions inspections must be done a bad gas cap would cause you to fail. Even one in good enough condition to keep the engine lights from going on would fail. Part of the inspection is to remove the cap and put it on a machine. Even very slight cracks in the gasket will net you a 'fail' until you replace it.

 

[stinger]

Here in AZ, at least in the Phx area where annual emissions inspections must be done a bad gas cap would cause you to fail. Even one in good enough condition to keep the engine lights from going on would fail. Part of the inspection is to remove the cap and put it on a machine. Even very slight cracks in the gasket will net you a 'fail' until you replace it.

That is a fact i failed my emissions in Mesa,AZ first for what was comin out the pipes then on the retest failed cause of the gas cap . man i was pissed they could have checked that cap the first time.