Been chasing gradually worsening symptoms of start & yoyo the past coupla months. Started needing pump-priming & at least 2 key-turns to start when engine sits overnight. Gradually worsened to hard-starting even when warm. Suddenly, random yoyo at pre 3k rpm became prevalent & stubborn. From fun, spritely, awesome drive to 1 very unpredictable & struggling ride. Then BAM, original damper went on a city traffic drive. ATI in, problems solved. Right? NO! Totally unrelated. You gotta think this was an abused high mile R53. Again, NO. Just 45k on the clock of a meticulously maintained 02.
Any sound mind would go through the usual suspects.
1.Started w/ new OEM plugs & wires. NO.
2.Ethanol-free vPower. NO.
3.Bypass valve. NO.
4.New OEM fuel filter. NO.
5.Vaccum tube. NO.
6.New Fuel Rail Pressure Regulator. Still NO.By this time, fuel pressure read just 22psi instead of above 40-50+psi when pump activates, instant zero
when pump off.
7..Gotta be the Fuel Pump! Right? NO. I've now a new Walbro kit for MINI on standby.
I'm not very sure if this is rare or anyone has seen this happen. Upon extracting the pump assembly, the flexi feed tube from pump to filter was torn. This on an untouched pump in a virgin tank. Replaced temporarily w/ a gates 5/16 fuel line for testing. Now old AWESOME IS BACK!
Learned a ton of new knowledge thru this diagnostic journey, gained new-found friends in a handful of MINI Samaritans. All worth it. It was challenging & to finally nail it, FULFILLING! I;m just THANKFUL.
Hope this helps should this rare condition strike you.

 

Knowing the Gates fuel line that replaced the torn OEM pump tube was just an SAE 30r7, I didn't want to wait too long to replace it w/ hopefully a lifetime fix. Devised a metal tube coupled w/ SAE 30r10 end tubes to replace the 2 day old fix. True enough, lucky to have dug in the tank again. The 2day old tube submerged in petrol showed rapid deterioration. Pic would show bloating, permeation & it's now a soft tube. Imagine if that had stayed a few days longer.
Hope this will guide those who might have same problem.