E.E.S - is this only on the cali emission K5s?

[wazzabie]

E.E.S - is this only on the cali emission K5s? Era late 70s. I think this stands for Evaporative Emissions Systems. I have federal emissions without the charcoal canister. I ask because the gas tank cap I have states for E.E.S. 1978 K5. I wonder if it is ok to use this gas cap on the federal emissions.

 

[Wes Harden]

I think you want a vented cap. EES is not an acronym I am familiar with and I held a California bar 80 emissions repair license. Worked on abd test ca cars and trucks for 40 years

 

[wazzabie]

I think you want a vented cap. EES is not an acronym I am familiar with and I held a California bar 80 emissions repair license. Worked on abd test ca cars and trucks for 40 years

I'm learning there is a vented and a EES non-vented cap I assume. Were the late 70s K5 equipped with either gas cap. This 78 K5 is using a vintage aftermarket ESS gas cap for some time. The seal around the gas cap has cracked. With rockauto there is no selection for vented and non-vented gas caps.

 

[wazzabie]

On top of the fuel tank I have three outlets. One is to a plastic piece that is a vent for the gas tank. So I don't think it matters if I get a vented or non-vented gas cap since the tank is vented.

 

[Wes Harden]

So most of the new caps, for old cars, will operate like check valve. They will allow air in the tank as fuel is used, then seal when the tank warms during the day seal to stop evaporation. then air back into the tank when it cools.

 

[dyeager535]

With a vented tank you should have no problem running a "non-vented" gas cap. Really they vent, but it's quite high, like 16PSI.

I remember years back trying to find a new manufacture vented GM gas cap replacement, and I couldn't. I don't get it, as that was standard equipment and is absolutely necessary for those vehicles. You can make your own vented cap FWIW, the later ones aren't really that complicated to disable the valves in them.

Non-vented is better if possible to run however, as fuel can and will get out of the cap depending on various factors.