My 2001 R1100RT (105,000 miles) had a sudden running issue six weeks ago. Suddenly lost power, wouldn't idle, ran like crxxxp.

I spent 3 weeks attacking fuel delivery; replacing fuel tank hoses, filter and fuel pump. Then I pulled, examined and replaced the Hall Effect Sensor with a new HES. Still not fixed, so I threw in the towel and had my dealer pick it up.

So far they have done a little bit of diagnostics and found that fuel pressure isn't holding; it goes up to 43 psi but when they check it later it has dropped. So they're suggesting replacing the fuel pressure regulator. They also found extremely low compression on the left side, 155 on the right. They still have to do a leakdown test but it looks like a valve is broken.

It seems unlikely that both the FPR and the valve failed at the same time and it's most likely that running on one cylinder was the immediate cause of the running problem.

My question is, what symptoms would one see if the FPR was not holding pressure properly? Not total failure, just not holding pressure. R&R the FPR means a few hours to put the tail at least partially in the air. I've probably been running the bike this way for a while - and before the loss of compression it was running great. What's the thought of just repairing the valves and not splitting the bike in half? I'm good with regular maintenance stuff; valve work and splitting the bike are beyond my abilities.