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E46 (1999 - 2006)
The fourth generation 3 Series (E46 chassis) was introduced in 1999 and set the standard for engineering and performance during it's years of production including being named to Car & Driver's 10 best list every one of those years! ! -- View the E46 Wiki

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  #1  
Old 06-19-2011, 10:26 AM
frankyzambony frankyzambony is offline
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Location: california
 
Join Date: Nov 2008
Posts: 3
Mein Auto: 325
Smile E46 Fuel pump fuse blows with a happy ending.

BMW E46
2000 323i sedan.

This is a strange story with a happy ending...

I set out to do an entire cooling system overhaul (Radiator, Expansion tank, Water Pump, Thermostat, 3 hoses and 2 belts)

Spent the better part of an entire week working a little here and there - finally came time to put everything back together and start-er up.

She fired up like a champ, I was montitoring the water reservoir - worried about air pockets that might cause the engine to overheat.

After about 5 minutes of running, the engine just stopped. Wont restart. - Pissed off I called it a night.

Score - BMW 323i 1, FrankyZambony 0

Thought about possible causes all night (Didnt sleep well) then hit it again first thing in the morning to try and isolate the problem.

At first, I thought maybe I fried the engine due to an air pocket - but the more I thought about it the less I believed that theory.

The car only ran for about 5 minutes before it stopped running - I dont think there was enough time to get the engine temp to critical.

So, I set off searching the BMW forums. After about an hour of random surfing I came across some youtube posting of a guy talking about a blown fuel pump fuse.

Turns out, there are actually TWO fuses for the fuel pump - one is in the glovebox the other is in the fuse compartment under the hood near the drivers side firewall.

I pulled the fuse block out from the under-the-hood fuse box and sure enough - the 20 watt fuse was blown. (Middle fuse in a 5 fuse block)

OK - so at least I am on the right path... Now why did the fuse blow ?

Ran down to the hardware store and purchased some fuses, put a new one in and the minute I turned the ignitian key the fuse blew again !!!

So I am trying to understand how I could have possibly screwed up the fuel pump by re-doing the coolant system.

Back to the forums, I followed a couple of procedures to isolate fuel pump problems - Pulled the back seat, removed the fuel pump connector and inserted another fuse.

BAM - that fuse blew as well (WITHOUT the fuel pump attached) - that rules out a bad fuel pump.

Back to the forums again - I found some article that casually mentioned that the circuit that runs the fuel pump also runs SOME OTHER electronics in the car.

At that point a light came on in my head - perhaps the 6 or so electrical connections to cooling components that I removed and inserted (Temp sensors, level sensors etc) might have a short.

So now its process of elimination.

Pulled the connections off the lower hose temp sensor, the FAN sensor and the large plug that connects on top of the radiator - inserted new fuse, tried again...

BAM - fuse blew.

Next iteration, I removed the sensor from the Thermostat - inserted new fuse turned the key AND THE CAR STARTED RIGHT UP !!!

Pulled out the ohmmeter and measured 1 ohm across the thermostat temp sensor - compared it with the one I took out - it had about 16 ohms.

So I pulled out the "NEW" thermostat, put back the original and all is well.

The datapoint that did not compute for me is why the car ran for what seemed like 5 minutes although I am sure the fuel pump fuse probably blew immediately - Now that I think about it, the lines to the engine probably had enough fuel in them to keep the engine idling for a few minutes.

This "NEW" thermostat was ordered online from some ebay store - I know - you shouldnt use crap parts and you get what you pay for.

The "NEW" thermostat is going back and the score now is FrankyZambony 1, BMW 323i 0


Hope this helps someone out there isolate a blown fuel pump fuse.
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  #2  
Old 06-19-2011, 12:03 PM
catso's Avatar
catso catso is offline
catso
Location: Chicago
 
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Posts: 2,946
Mein Auto: 2000 323i, 1988 528e
Quote:
Originally Posted by frankyzambony View Post
BMW E46
2000 323i sedan.

This is a strange story with a happy ending...

I set out to do an entire cooling system overhaul (Radiator, Expansion tank, Water Pump, Thermostat, 3 hoses and 2 belts)

Spent the better part of an entire week working a little here and there - finally came time to put everything back together and start-er up.

She fired up like a champ, I was montitoring the water reservoir - worried about air pockets that might cause the engine to overheat.

After about 5 minutes of running, the engine just stopped. Wont restart. - Pissed off I called it a night.

Score - BMW 323i 1, FrankyZambony 0

Thought about possible causes all night (Didnt sleep well) then hit it again first thing in the morning to try and isolate the problem.

At first, I thought maybe I fried the engine due to an air pocket - but the more I thought about it the less I believed that theory.

The car only ran for about 5 minutes before it stopped running - I dont think there was enough time to get the engine temp to critical.

So, I set off searching the BMW forums. After about an hour of random surfing I came across some youtube posting of a guy talking about a blown fuel pump fuse.

Turns out, there are actually TWO fuses for the fuel pump - one is in the glovebox the other is in the fuse compartment under the hood near the drivers side firewall.

I pulled the fuse block out from the under-the-hood fuse box and sure enough - the 20 watt fuse was blown. (Middle fuse in a 5 fuse block)

OK - so at least I am on the right path... Now why did the fuse blow ?

Ran down to the hardware store and purchased some fuses, put a new one in and the minute I turned the ignitian key the fuse blew again !!!

So I am trying to understand how I could have possibly screwed up the fuel pump by re-doing the coolant system.

Back to the forums, I followed a couple of procedures to isolate fuel pump problems - Pulled the back seat, removed the fuel pump connector and inserted another fuse.

BAM - that fuse blew as well (WITHOUT the fuel pump attached) - that rules out a bad fuel pump.

Back to the forums again - I found some article that casually mentioned that the circuit that runs the fuel pump also runs SOME OTHER electronics in the car.

At that point a light came on in my head - perhaps the 6 or so electrical connections to cooling components that I removed and inserted (Temp sensors, level sensors etc) might have a short.

So now its process of elimination.

Pulled the connections off the lower hose temp sensor, the FAN sensor and the large plug that connects on top of the radiator - inserted new fuse, tried again...

BAM - fuse blew.

Next iteration, I removed the sensor from the Thermostat - inserted new fuse turned the key AND THE CAR STARTED RIGHT UP !!!

Pulled out the ohmmeter and measured 1 ohm across the thermostat temp sensor - compared it with the one I took out - it had about 16 ohms.

So I pulled out the "NEW" thermostat, put back the original and all is well.

The datapoint that did not compute for me is why the car ran for what seemed like 5 minutes although I am sure the fuel pump fuse probably blew immediately - Now that I think about it, the lines to the engine probably had enough fuel in them to keep the engine idling for a few minutes.

This "NEW" thermostat was ordered online from some ebay store - I know - you shouldnt use crap parts and you get what you pay for.

The "NEW" thermostat is going back and the score now is FrankyZambony 1, BMW 323i 0


Hope this helps someone out there isolate a blown fuel pump fuse.
Interesting, sometimes new parts are indeed faulty, but you may not have actually solved your problem. If it returns, keep us posted.
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  #3  
Old 06-19-2011, 12:13 PM
mujjuman mujjuman is offline
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Great investigative work!!! I would not have thought of that.
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  #4  
Old 06-19-2011, 12:58 PM
veli510 veli510 is offline
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Mein Auto: 2001 bmw 330i
You need a case of beer and some jerky. Then take a long nap because you're car loves you. Keep up the good work!
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  #5  
Old 06-19-2011, 04:25 PM
jcourcoul jcourcoul is offline
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Location: Mexico
 
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Mein Auto: 2006 325Ci
The fuse maker also loves you very, very much.
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  #6  
Old 11-19-2011, 08:22 AM
floridawelsh330 floridawelsh330 is offline
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Location: Orlando
 
Join Date: Nov 2011
Posts: 2
Mein Auto: 2001 330i
Same Thing Happened to ME.......lol

Frankyzambony, you are my hero until I have another problem on my 330i.
I too had just installed one of the "EBAY Metal housing" thermostats and experienced overheating problems for a day or two until it just cut out on the highway. The sensor or coil or whatever it is on the thermostat was shorted and blew the fuse.

I found your post, thank you, you saved me a lot of headaches.

PS. A plumbers drain nut wrench works just as well as a clutch fan removal tool......
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  #7  
Old 11-19-2011, 08:30 AM
sunnyjay sunnyjay is offline
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Location: CA
 
Join Date: Nov 2011
Posts: 95
Mein Auto: 01 330ci
Is there a way to replace the broken sensor on the metal housing thermostat? I like the idea of having a metal termostat over the plastic piece.
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  #8  
Old 11-19-2011, 06:59 PM
floridawelsh330 floridawelsh330 is offline
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Location: Orlando
 
Join Date: Nov 2011
Posts: 2
Mein Auto: 2001 330i
I don"t think it's a sensor, I think it's some kind of solenoid/coil valve. The ones I have are definately not replaceable. I too liked the idea of the metal housing but I guess it's not the housing that fails, it's the Valve and sensor/coil. I may be wrong, just stating what i've seen on my troubleshooting searches.
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  #9  
Old 11-19-2011, 09:31 PM
sunnyjay sunnyjay is offline
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Location: CA
 
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Posts: 95
Mein Auto: 01 330ci
I will order one of the metal housing thermostat to see what i can find

Sent from my SGH-I897 using Bimmer
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  #10  
Old 01-29-2012, 08:40 AM
ridgewalker ridgewalker is offline
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Location: Tucson
 
Join Date: Jan 2012
Posts: 1
Mein Auto: 2001 330i
Thanks . . . hoping for another happy ending.

Thank you for your post. I replaced my fuel pump. Car ran great all day yesterday. This morning, it's back to "popping" the fuel pump fuse.

Thanks to you, I will look at the cooling system next. (Had a brief cooling system light come on weeks ago. Never would have guessed the two could be connected.)

Really appreciate your post.
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  #11  
Old 04-14-2012, 06:53 AM
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smolck smolck is offline
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Location: Birmingham, AL
 
Join Date: Jul 2007
Posts: 22,348
Mein Auto: 2004 ZHP Sedan
I just wanted to bump this and say thanks to the OP for this thread. I encountered this problem for a car I was working on yesterday. The lady said she parked it, and then it wouldn't start. The pump didn't prime so I tested it and it worked. I thought, I better check the fuse, sure enough, it was blown. Put another one in, turned the key and POP. I did a quick google search and found this thread. I disconnected the Tstat electrical connector to the harness and the car fired right up. No doubt I saved the lady a LOT of money on mechanics trying to diagnose that problem.

So again, THANK YOU!!!
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