Jeep has been sitting in the garage while I slowly finish working on it. I decided to take the jeep to get some gas. I started it and let it warm up. Drove to the gas station (about 3 miles). Took the cap off and a strong whoosh of air came out of the filler hose. Tried it again when I got home and gas sprayed out.
So, why is this happening? And what can I do to stop it?
Here's my setup:
232 with Team Rush
Running a gas canister (though it's a later model Jeep canister)
Also have a CTO controlling the purge signal*
I believe I have the OEM check and roll over valve
* I'm going to draw a diagram and take some pics of my setup in case that helps with the diagnosis.
I replaced my OEM evap canister with a more modern one...this one:
I followed the instructions listed here, but modified it to work with my TB (no bowl vent). But, looking back at this diagram, I wonder if I should have T'd my purge line to the PCV line rather than the Manifold Vac line.
BTW, I have a CTO that looks like the one pictured below (but with two ports, not three). Does it matter which port I plug the vac hoses into? I mean, if I swapped the hoses/ports would that make a difference in my setup?
So did you drill out the plug on the canister the tank vent is connected to?
It shouldn't make a difference on a 2 port CTO which hose the vacuum line is connected to.
Hopefully it opens when hot and not close....
It should also be connected to a ported vacuum connection on the Throttle body and the Purge to the MAnifold vacuum or T into PCV line as you are thinking.
This is to keep it from opening during idle.
Just ignore the EGR section of these schematic.
this looks like the purge signal is also tied into your manifold vacuum. I can see an interesting flutter going on here....
Re-plumbed the engine to resemble your last diagram, John. The only difference is that I T'd the PCV/TB manifold vac/evap purge line together. Is that okay? The intake manifold vac (under the TB) is now just operating the brake booster.
Results - so so. The WHOOSH! turned into a pssst when opening the gas cap. That's an improvement, but there's still pressure building up.
Can someone explain what a ported vac line is? Do you think there's a conflict with having a ported line running to a CTO? Could I take the CTO out completely?
BTW, Keith, the two LCV vent lines do both go to the tank.
ported vacuum is usually above the throttle plates so there is no vacuum when the throttle is closed. This is good because You don't need to have the purge line open enriching your mixture at idle or if there is nothing to purge, just creating a vacuum leak.
Same for the CTO, it wouldn't allow the purge to activate until the engine is warm enough otherwise it could cause too lean of a mixture.
Have you tried taking off the line to the tank to see if it still psssttt. That might narrow it down to canister or tank.
It could be the heat of the day causing the gas in the tank to expand also.