How to replace valve assembly, vent (ORVR)ORVR

Welcome to 2CarPros. Your description says the car was parked with a tank at least half full and left alone. The peanut brittle is what is left of the gas that was in it after the fuel evaporated. If this is a steel tank I wouldn't even try to use it as the interior is probablt starting to rust and corrode. If plastic I would be very careful to clean it very thoroughly. Next I would replace every fuel line the fuel rail and injectors as well. The dehydrated fuel would be in everything related to the fuel system and would constantly be plugging the system as it broke free inside the fuel parts. Inside the injectors the varnish would plug the jet tips and the solenoid assembly. If you do use the original tank I would also add an inline fuel filter that is easily changed.

If that image is your tank you can take if off at the connections then remove the charcoal canister and replace it. I looked for a better diagram but the Honda City wasn't sold in the US, just everywhere else! On many Honda's they use a valve that twists into place like the one in the image. However they also have ones that are glued into the tank. Those are not easily removed, However you could use Acetone to flush the valve out, but it would need to soak to soften the varnish. Think you could take a picture of the pieces and tank and post it here? That would let me see the exact items. I would just use the Fit diagrams as they are based on the same chassis, I just don't trust that Honda actually used the same exact parts.

Okay, being a Civic makes it much easier to deal with. The tank straps go in place as in the picture. In your picture the longer legs to the left go toward the front of the car. Usually they are a fight to install as they use the bolts to tension the straps and hold the tank so you end up doing the octopus dance trying to hold things in place. What I normally do is get a floor jack and set the strap in place over it, then jack it up to hold the tank into place. Now you can position the strap and tighten it in place. Put all 4 bolts in a few threads before you tighten any down.

You are welcome.