Cranks but won’t turn over...sometimes
 

We just picked up a 2005 rx8 manual 6 speed repo at auction. It’s got roughly 98k miles on it. It will start when it’s been sitting and then again right if it wasn’t driven very far/long but every other time we try to start it, the engine won’t turn over. Put a new battery in it but we are starting to think it is a fuel issue. I have a scooter that did something similar and it ended up needing a new petcock valve and new fuel hoses. Tomorrow we are going to replace the spark plugs and do all the pertinent fluid changes but being new rx8 owners, I figured I better get involved in a group or forum for support. Thanks in advance

You will need to get a compression test done by someone with a specialised rotary compression tester. These engines are known for wearing out apex seals.

Also common to need ignition coils, leads & spark plugs.