Two weeks ago today, my buddy and I drove our R53 (my 2006 modded S and his 2006 JCW Checkmate) on an intended loop into NM from my home in easternmost AZ. We fueled up, then headed east prox 100 miles before turning SW towards our intended lunch stop. Prox 15 miles onto that lonely secondary road, the engine shut off suddenly without stumbling - same as reported in post # 327 of my long topic. Coasted to (limited) road shoulder and radioed my buddy. As before, cranked but no start. We were well beyond cell range, so I drove back in his to the main highway, called the few tow services within 100 miles and ended up getting the service most local to my town to drive nearly 250 miles roundtrip to arrive with roll-back, haul it home and roll it into my garage. The driver was very experienced, thus no damage to the chin spoiler or air dam I replaced a few years ago. Done improperly, damage to parts alone could have easily exceeded the towing cost.

So then, started diagnostics at home with Foxwell NT510 able to communicate with OBD2 whereas my OBDLink BT dongle wasn't able. Foxwell showed an EWS error. I replaced the 12v battery since last time driven due to battery tender not going into float mode and completely draining that otherwise not-old battery. Searching indicated an extended battery disconnect time can cause EWS synch errors, so with resolution hopes, I contacted @adriancl whom had successfully performed a custom tune before the original pump/filter failed. Today, we did another remote session with EWS now re-synched. Long story shortened (having checked fuses/relays plus swapping some from said buddy's R53 JCW), fuse F34 was blown. Changed that out and it started, ran cleanly at idle and revving (in garage), then back to idle. Then, the engine shut off again as before. Yep, F34 blown again, so Adrian suggested replacing with 15A vs 10A fuse. Engine cranked and stumbled but did not start. At that point, Adrian suspected a bad fuel pump and suggested checking relative psi at the fuel rail. We ended our remote session at that point.

I let the engine rest, then retried starting which repeated the stumble but then the engine caught, idled smoothly and revved normally several minutes -- until it didn't -- with another blown fuse (repeated with new 10A, then 15A with same result). Since it started and ran smoothly for several minutes, no need now to check fuel rail pressure. Current thinking is the fuel pump is struggling to maintain 50 psi spec, heats up and then blows the fuse to protect the pump and wiring. If so, either the current OEM replacement pump or filter or both must be replaced again - despite the low mileage driven since 2022. This time, must be DIY since I'm a long ways from authorized MINI service or any known competent independent repair shops.

As outlined in 2022, quite spendy with expectation of full resolution. With DIY this time, perhaps starting with the filter would indicate if any debris is evident. I'm supposing replacing F34 with a 20A (vs 10A spec or 15A currently) might delay blowing another fuse, however seems doing that would be detrimental to the pump and wiring. I'm open to suggestions from anyone here with related knowledge and skillset beyond my own.

 

Something is causing you to have excessive current draw. 15 amp as a short term is understandable. 20 is a bad idea. I don’t see the tune having any real influence on the pump. I have had my 05 since new. Did a filter only at 100k ( 10 years )? Did a new pump ( VDO ) and filter at 135k. Now at 184k what is the fuel pressure at the rail, and have you ever touched fuel pressure regulator ( I have not touched mine ). Check wiring, connections, and ground points.

 

First off, thanks for the thoughtful response - appreciated!

Agreed on not exceeding 15 amps for F34. The car will not be driven (far, if at all) until the problem root cause is determined and corrected. Also agreed WRT not being related to the custom tune. As outlined 3+ yrs ago in the linked post, the MINI dealer towed to then discovered low pump output (vs +/- 50psi spec), as well as cable harness casing material on the original fuel filter (likely from fuel gone bad in long term storage), so evacuated and swabbed-out the tank before replacing both the pump and filter with new OEM MINI parts. Being in that dealer's service department 100 miles from my home, I did not see what that harness looked like. With fresh premium fuel since then and frequent enough driving intervals, fuel quality would be an unlikely issue now. Having not had eyes-on, I'm unsure what the cable harness looks like and if that is normally fully immersed in fuel.

Since that repair and with the mods and tune, my engine feels stronger than does my buddy's 2006 R53 factory JCW (prox 11k miles), thus clearly more power than 210hp rated. With a good fuse in play (10A or 15A), the engine idles and rev's smoothly in my garage without stumbling or hesitation. I don't have a fuel pressure gauge suitable for measuring at the Schrader valve. Checking the regulator (which I haven't touched - other than physically when swapping to OEM 380cc injectors) and the ground points (nothing obvious there, noting currently at 9.7k miles) are prudent steps. I'll do more reading my Bentley manual before proceeding further. In the meantime. my R53 is limited to being "Garage Art"...