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E36/7 Z3 (1996-2002)
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Old 12-04-2011, 08:54 PM
RacerXTreme7 RacerXTreme7 is offline
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Location: VA
Join Date: May 2011
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Mein Auto: Z3 Coupe
Z3 Fuse/Electrical help!!

I have a 2001 Z3 Coupe 3.0 (M54) and am having an electrical issue and need some help.

Short Story (refer to pics attached), I need to know what the 20 AMP fuse is in the 5 fuse engine fuse pack located on the passenger side E-Box. Its the center fuse (F3??) of five fuses. It blows randomly (idling, while driving etc.). It appears to be linked with the fuel system, as when it's blown the starter will turn the engine over, but no fuel gets injected (injectors, or fuel pump? I don't know).

LONG STORY So I did some tuning up which included changing the oil (Castrol Synthetic), did a Seafoam internal engine cleaning/treatment, and spark plugs.

Pulled a vac line, let it suck in half a can of Seafoam. Let it set while I changed the oil. Started it up, of course it smoked and misfired, it eventually cleared up and ran fine. Let the engine cool a bit, and swapped the spark plugs out. Fired right up, went for a drive all is great.

Did some engine detailing, basically sprayed some mild engine cleaner (environmentally friendly, so you know it's mild), did some scrubbing, hosed it off. Fired the engine back up, runs fine. Used a leaf blower to speed up the drying while the engine is running. Closed the hood, wash the entire outside of the car meanwhile the car is purring. An hour of idling and I'm drying the car off I decide to turn the heat on inside the cabin, continue drying the outside then the engine dies. I attempted to restart and no love. Ran a quick scan of the OBDII and got the following:

P1619 MAP Cooling Control Circuit Signal low (I suspect this is an old code, I recently replaced my thermostat with an aluminum one and found the old one was bad).

P1451 Diagnostic module Tank Leakage (DM-TL) Switching Solenoid Control Circuit Signal Low

P1445 Diagnostic module Tank Leakage (DM-TL) Pump Control Circuit Signal Low

P1349 Misfire Cylinder 4 with fuel cut off (I think this is from when I did the Seafoam treatment and it misfired a lot before it cleared out).

P1353 Misfire Cylinder 6 with fuel cut off (I think this is from when I did the Seafoam treatment and it misfired a lot before it cleared out).

A week went by without having the time to check the car out. My initial thoughts were something got wet and shorted during my engine detailing, but a week of sitting and still wouldn't start.

So a week later I'm trouble shooting and I checked fuses and found that the 20 amp fuse on the engine control fuse block (5 fuses located in the E-box on the passenger side {see pics}). Replaced it and it fired right up and ran great YA!!. Idled for half an hour with varying rev's, went for a short cruise around the neighborhood, then went on the interstate to run it up in the RPM's then it died again. Replaced the same blown fuse (nervously on the side of the freakin Interstate) drove home. Ran an OBDII scan again and found:

P0171 System too lean (Bank 1).

P0174 System too lean (Bank 2).

P1349 Misfire Cylinder 4 with fuel cut off.

P1353 Misfire Cylinder 6 with fuel cut off.

I'm thinking the above codes where thrown when the fuse blew turning off the fuel system causing lean and misfiring maybe and are results of the blown fuse and not the reason for it.

The SES light never came on before the engine died when I was washing it or when I was driving it.

Searching the net for hours and hours what I did find out about that fuse is:

The small engine management fuse pack that is in the under-hood e-box (on the driver’s side) contains five small fuses. The 20-Amp fuse is #3 and it has the following circuits on it:

* A/C compressor clutch
* Camshaft position sensors
* Crankshaft position sensor
* DME & Fuel pump relays
* Evaporative system leak diagnostics pump
* Mass air flow sensor
* Secondary air pump
* Electric thermostat

Unfortunately that is for a E46 found here---> http://blog.bavauto.com/3744/bmw-e46...0-amp-blowing/

I did a check with the engine running and turning the AC on and off, that's not the culprit. The secondary air pump only comes on when the engine is cold, the fuse blew both times while the engine was well warmed up, not the culprit either. The only code I see in common with the above is that leak pump. hmmmmm

And I found this:

The fuse functions are in Bentleys, but depending on the year and model you have they don't always match the Bentleys description, see page 610-34.
This is fuse panel 3 for F1 to F5
According to Bentleys:
F1 open (no fuse)
F2 30 Amps, Fuel injectors, Engine control module
F3 20 Amps, Cam sensors, MAF, Crank Sensor, Thermostat
F4 30 Amps, Heated O2 sensors, Tranny control module
F5 30 Amps, Unloader relay, power to coils

Here is what my 2000 540/6 really has. (might be more that below, this is what I could trace out)
F1 30 Amps, MAF, Cam sensor #1, DME, T-Stat, Evap emission valve
F2 30 Amps, Fuel injectors, Both Vanos solenoids, Cam sensor #2, Secondary air injection pump electrical valve.
F3 30 Amps, Cam sensors, MAF, Crank Sensor, Heated O2 sensors.
F4 30 Amps, DME
F5 30 Amps, Unloader relay, power to coils

Unfortunately that info is for a E39 found here---> http://www.bimmerfest.com/forums/sho...00#post6375400

I'll scan it again tomorrow and see if any codes exist, I can't get the problem to come back again (The fuse won't blow now).

My thoughts....

Maybe that fuse is linked to the Fuel Leak Diagnosis Pump and the pump is bad causing an over current? I searched for this too, but not one posted about it or a single image on the entire freakin net showing where this thing is located. I even removed the pass side inner fender liner to not find it.

Sorry for the long post! And I don't think it's a moister problem, the car sat for a week and today was dry and it ran fine for over an hour before that fuse blew again.

HELP!!!!!!!!!!!!! What is that damn fuse linked too?!?!

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Old 12-05-2011, 06:59 AM
dkindig dkindig is offline
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Mein Auto: '01 Z3 3.0i Roadster
F20 runs to the power distribution box (P90) and feeds F13. Too extensive to give you a narrative here. If you'll PM me your email addy, I will send you a copy of the '01 wiring diagrams.
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Old 12-05-2011, 07:16 AM
Ron Stygar's Avatar
Ron Stygar Ron Stygar is offline
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Mein Auto: Z4 M Coupe 6LL93033



Last edited by Ron Stygar; 12-05-2011 at 07:17 AM.
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Old 12-05-2011, 07:51 AM
RacerXTreme7 RacerXTreme7 is offline
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Mein Auto: Z3 Coupe
Thanks guys! All the manuals I've found were for other BMW models or older Z3's (97-99).
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Old 12-05-2011, 08:05 AM
RacerXTreme7 RacerXTreme7 is offline
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Location: VA
Join Date: May 2011
Posts: 33
Mein Auto: Z3 Coupe
Thank You both!!


Page 83, looks like it's fuse # F203??

It appears it goes to SEVERAL things! One of which is the Water Thermostat. Strange, I just did an entire coolant system revamp which included replacing the bad plastic one with a new all aluminum one. Maybe I got a defective one?

Mass Air Meter
Crank Angle
Both Cam position sensors

and to another fuse bank (F18, F13, F46, F26)
which are connected to Fuel pump
Fuel pump relay
Leakage pump
and Brake lights

Damn, well that a lot of possibilities!


Last edited by RacerXTreme7; 12-05-2011 at 08:12 AM.
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Old 12-05-2011, 10:08 AM
RacerXTreme7 RacerXTreme7 is offline
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Location: VA
Join Date: May 2011
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Mein Auto: Z3 Coupe
Well, I think I can eliminate the Leak detection pump. It is only activated when the car is off:

The ECM only initiates a leak diagnosis test every second time the criteria are met. The criteria
is as follows:
• Engine OFF with ignition switched OFF.
• Engine Control Module still in active state or what is known as "follow up mode" (Main
Relay energized, control module and DME components online for extended period after
key off).
• Prior to Engine/Ignition switch OFF condition, vehicle must have been driven for a minimum
of 20 minutes.
• Prior to minimum 20 minute drive, the vehicle must have been OFF for a minimum of 5
• Fuel Tank Capacity must be between 15 and 85% (safe approximation between 1/4 -
3/4 of a tank).
• Ambient Air Temperature between -7OC & 35OC (20OF & 95OF )
• Altitude < 2500m (8,202 feet).
• Battery Voltage between 11.5 and 14.5 Volts
When these criteria are satisfied every second time, the ECM will start the Fuel System Leak
Diagnosis Test. The test will typically be carried out once a day i.e. once after driving to
work in the morning, when driving home in the evening, the criteria are once again met but
the test is not initiated. The following morning, the test will run again.

Strange how it threw codes though....

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Old 12-05-2011, 12:11 PM
RacerXTreme7 RacerXTreme7 is offline
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Location: VA
Join Date: May 2011
Posts: 33
Mein Auto: Z3 Coupe
Failing Fuel pump or fuel pump relay? That would explain the lean/misfires.....

Anyone know what kind of rail pressure I should see at idle? Is the fuel line pressure regulator rising rate (has a vac line on it) or constant pressure?

Thinking out loud

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