About 10 minutes after takeoff I noticed the #1 CHT slowly climbing and reaching some ridiculous temp like 480. Turned back to airport and figured another CHT probe failure. (These GEM probes have been failing about one a year.) At the hangar I uncowled the engine and noticed a strong fuel smell. That is unusual. I started looking closely and noticed fuel stains on the firewall. Uh-oh. Fuel leaks are a really, really bad thing. Some more blue stains appeared to be on the RG15980 Romec fuel pump. I pulled mixture all the way out and hit the boost pump and got in there with a mirror and a flashlight. Fuel was puking out of the fuel pump big time. (Ruptured diaphragm?) Thank you for failing Mr CHT Probe! Because of this coincidence I was alerted to a big time problem.

So, good news - found a huge problem on the ground. Bad news - the engine driven fuel pump is going to be a nightmare to R&R.

Always nice to have a smoking gun like that.