i have serched and read every rats nest thred on this site and others...but i still have some questions. In this thred from F A Q https://www.rx7club.com/1st-gen-archive-71/fuel-intake-rats-nest-removal-79-rx-7-pictoral-457961/ it explains it quite clearly. This is how i bought the car. You can see that the vac hoses are set up different to in the thred. With the fuel cap on, it won't idle. With the fuel cap off it idles nicely. It also creates a big vacume in the fuel tank with the cap on. Soon as you release the fuel cap...air rushes in, and up comes the idle...otherwise it just stalls. I drilled a small hole in the spair fuel cap...and the idle is fine. Only problem is when you go around a right hand corner, it will flood for a bit then clear itself.
The vac hose to the tank has a small plastic insert that fits into the steel line to the tank. It has a very small hole in it to allow air through. I removed this once and then put it back cause the car ran like crap. What is it for? All help would be good as this has me stumped.
Here's a pic.

 

FSM, I'm in the process of reinstalling the rat's nest after trying to get rid of it.

Ray

 

First thing I see is the return fuel line is missing the restrictor, which also acts as a one-way valve. It's the rubber line just above the ss braided one for the tank vent. The other thing to check is the charcoal canister, it may be plugged. Doesn't happen often.

 

Looks like you are trying to do a rats nest removal on an S1. Totally different setup from the the S2/S3 nest.

 

thanks Trochoid...i'll ring the local mazda dealer and see if they can get one for me.
Rouge Wulff...your exactly right! 1st gen ser 1 1979 rx7.

 

anyone else like to take a shot at the trouble i'm haveing? Have a read of my pic and see if you see anything weird or different...