SOLVED: it was the fuel pump!

I'm helping a neighbor try to get his 2003 Mini back on the road. The car has been running rough for a long time but now refuses to start. Interestingly, it will start with a shot of starting fluid, after which it runs for 15 seconds or so, seemingly like normal. Then it dies. Trying to start the car with no starting fluid will result in one or two seconds of a running engine, tops.

Key details:
2003 Mini 1.6L, CVT, ~200k
Pressure in the fuel rails (confirmed via Schrader valve)
Clean MAF, throttle body
New spark plugs, new coil packs
Fuses are all good. I tried swapping around the relays with no change.
Battery is ~5 years old but appears to hold a good charge.
New thermostat housing, thermostat, coolant sensor
Fuel pump and filter replaced <6mos

Prior to the no-start issue, the car ran out of fuel and would not restart. I found the original coil pack had no spark on one post, so we replaced the coil and the car ran normally after that, for one day. Mini died while on the road and won't start unassisted.

I'm so confused! We have fuel, spark, and compression, but it won't run! Unless we cheat with starting fluid... then it runs great!

 

Have you checked the idle air control valve? Sometimes, these get clogged with carbon and won't work right, or the stepper motor just fails. Another thing you can do for little to no money is disconnect the O2 sensor to see if it runs OK. THis will throw the PCM into limp home mode and keep it in open loop operation. This can help diagnose issues with the exhaust before the sensor as well as a faulty sensor. Since it was running poorly, is the catalytic converter plugged up? Try tapping on it with the handle of a screwdriver, gently. If it rattles then the catalyst matrix has failed and may be plugging the exhaust. If not, you can also do a backpressure test on the exhaust by screwing a compression tester in place of the O2 sensor. It should show very little pressure, like under 5 psi at idle. If not you have an issue in the exhaust. I bring this up because it ran rough for so long that it may have destroyed the car due to either oil or excess fuel . I would also do a proper compression test and perhaps do that first. Since it ran bad for so long that the owner didn't even notice a dead cylinder, the car may have a bad engine. In that case, no amount of sensors will fix it.

 

Am I missing something here? Should a 2003 have both plugs and coil packs?

 

That's a good idea re: the o2. There were no MILs related to the o2 but it wouldn't hurt to check. The compression on the engine is good, it is _capable_ of running. After replacing the coil pack it did seem to run normally. The car was being driven the last time it died, and the motor seemed to have normal power. I'm not sure exactly what the previous rough condition was like since it's not my car and I wasn't driving it then.

As far as I can tell there is no idle air control valve on this engine, just a dbw throttle body. The throttle body appears to operate as normal—it's open a crack at idle and it moves through the range when the gas pedal is depressed.

Typo! One single coil pack, just recently replaced.

 

Reads like a bad fuel pump. Starts with a shot of starter fluid then quits after 15 seconds. That 15 seconds can't all be starter fluid it has to be gas. But then the pump quits and that's that.

Turn the key off wait a while maybe not long and the fuel pump works at key on and maybe a bit after then quits again.

Car probably did not run out of fuel but the fuel pump quit with low fuel.

 

It has only one coil! I didn't get it either! Unless it is so newer engine swap in, which would scare me!

 

You have fuel pressure but not necessarily fuel.

Do you have a noid light or oscilloscope to verify the injectors are getting their power? Are you sure the injectors are mechanically sound? I would also get an obd scan tool and try to capture all the data around the stall to look for any other signs.

After running out of fuel it's not uncommon to have the sediment in the tank get through the system. Maybe garbage is keeping the injector pintles from opening up (or closing). Also, a clogged fuel filter can still show pressure but have little flow through it. Someone else suggested the pump may be struggling or only working in bursts so that's an good place to look too.

 

That's certainly possible. I have seen pumps that either work or don't, but I've never seen a pump in bursts and spurts. Then again I have not repaired many 15-year old Minis.

Just one!

I think I'll move onto the pump and filter next. When it's running it seems to run strong, so injectors seem unlikely. I would expect an injector issue to manifest in consistent weak performance, not complete failure or normal operation. I do have a live-data scanner, I can check injector duty cycles during one of the bursts of operation.

 

Just a brief update in case anyone else stumbles across the thread: it was indeed the fuel pump. Replaced the pump and filter and it is now running great!

 

I am glad you got it solved, James!

 

Nice work. Check your hard brake lines if you have not already. I had to replace the left rear / Right rear is next. They are coated steel, and rust out. I replaced with Copper. Not a lot of fun, but better than no brakes.