1st Gen R53 Cooper S Most liked posts in thread: R53: Dead in traffic

THIS.... the bolded text above. Maybe Eric@helix or Herbie-53-guy can help point you towards this gremlin. They took care of Blake's MINI two years ago at the dragon when it had a bunch of electrical gremlins. Turned out to be this harness short.

 

First things first. Check (safely) that you have spark. It's pretty easy to do. The interwebs will have tons of how-tos. That'll probably be your culprit, and if it failed completely and suddenly, it's more likely a relay/fuse/ground fault than something like worn plugs or a failing coil. Plugs and coils tend to fade to death vs. total and complete sudden failure.

If you do have good spark, you're on to fuel. This will be more involved. First, check that you have gas in the tank. If so, you'll need to check fuel pressure at the rail which involves a special tool (available at any Auto Zoney type store), removing and replacing your intercooler and cranking.

 

First step get a code reader and check for engine codes.

Check or change your plugs and double check all your connections.
I have had even new plugs fail and the car not start. Buy OEM NGK plugs.

Put your car on charger so you do not kill a battery trouble shooting it.

 

What year is your R53?

There are some weird gremlin stories out there. For example on certain model years there is a spot on the firewall that rubs the harness and causes a hard to find short that tricks many people into replacing the body control module when it is actually a short in the harness.

Maybe this will trigger some of the brainiacs here on where this might be coming from.

 

Did you check the fuse box under the hood. There is a relay in there at times looks like it's fine, but has wiggled lose some.

 

I'm not certain how the pump (if its going bad) effects the gauges. Still sounds like an alternator/battery/grounding problem to me. What alternator amp did you get?

Do a simple load test on the battery with the car running (probe across terminals at idle) whats the voltage reading?

 

and too...

The power steering over loading the alternator I guess could happen but there's a fuse, F39, on the drivers side pillar fuse box that "associates" these two electrically. If its blown i.e. overload, then the alternator isn't charging the battery, then the system sees a low voltage and the pump stops working as it needs to see ~13V. Its a hungry bi-atch especially with the wheels turned full right or left (or WOT on some twisty's)

 

pull the power on the pump and see if it goes away. Its tight to get to but easy to pull to disable the pump.

 

The alternator only charges the battery. The car really won't run without a good battery. Your voltages sound about right and things going bonkers without the battery in the circuit is expected behavior.

and from one site I googled about how the charging system works this warning:

more basic info here http://www.bcae1.com/charging.htm

 

I'm not following this "and then battery unplugged: 17.7 V. "

 

Pretty sure he means got the car running, then took the + cable off the battery so
the car was running off the alternator alone, and the voltage went up to 17.7V.

I'm thinking a new alternator with a functioning voltage regulator should limit the
output to about 14.5 V give or take a little.

 

I agree. 17.7V is not a good thing -- thus the regulator.

 

@Cristo

BTW, BRG for the world! :cornut: