Well, I think charcoal canisters have been around a lot longer than a fuel tank pressure sensors. I really don't know the systems. Could be a good question kdracer73.

Very true, maybe theres some valve now, or maybe I read a false explanation. Either way, if you got your blue sticker this year its all good!

Blue sticker? You mean reg tag?

The diagrams found don't show a fuel tank sensor, but some do show a leak detection pump.... Evap self testing was pretty new in 96. All the info I found from Chrysler is vague. Some vehicles had leak detection pumps and some didn't, even in same model lines. Most early evap self tests used other sensors to check evap operation. The pcm would look at MAP ( manifold absolute pressure) and look for a change in manifold vacuum when the evap solenoid opened. Some systems would look for O2 sensor enrichment readings as the solenoid opened.

After spending an hour under the car looking for a pressure sensor in the tank, then searching... a lot for a PCM diagram to see if it had a hook up for it, I just saw the hook up for the leak detection sensor. Just 30 seconds before I read this I was wondering if the Cherokee used it in lieu of a tank pressure sensor.

So thats the answer I take it? Ug, should have just sent you a PM. Ha

Expert knowledge. Use it. Or crawl around your back, whatevs.:smack:

My 73 F250 built in Oct 72 did not have a charcoal canister. My cousins 73 F250 built in early 73 did have a charcoal canister. Back then the rules went into effect on Jan 1, now they apply to the model year. Made getting my truck smogged a PITA as the young guys did not believe me on that.

You had to smog a 73? Where and when?

I don't remember the last year but into the 1980's.
In approx 1977 I bought a 57 Pontiac and had to install the temp controlled vacuum advance to register it even though it didn't require semi-annual smog checks. Retro ones you cut the top radiator hose in installed this temp controlled valve, I just bent the hose and attached it at the end, the smog tech laughed. Had to remove the old style crankcase vent also, those were a 1inch metal tube that entered the engine near the distributor and snaked down to just below the bellhousing.
My F250 has valve cover breathers with rubber hoses that snake down to below the engine and dump the fumes there. :)

I bought the wife a garden tiller about 5 years ago - CA only model. It ran fine then after about 40 hrs started quitting on me. Turns out the CA special has a rubber hose as a crankcase breather that feeds into the air cleaner and those small engines can't adjust for even a small change in air/fuel mixture. Took the hose out of the air cleaner and it runs fine. Fuck CARB and the AQMD.

When they find a way to stop China's air pollution from coming here on the natural wind currants then I will consider playing by the rules.