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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 5 Series > E39 (1997 - 2003)

E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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  #1  
Old 09-12-2007, 07:54 PM
Scany1980 Scany1980 is offline
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Fuel pump fuse - more bhp!

So after driving at an event at VIR, I started the car one day and it died after two seconds. I suspected the fuelpump, but after alot of searching and diagnosing (since it took us three! checks to find the faulty fuse) it ended up being the fuel pump fuse. It looked like it's fine, so it's not broken by much, if you could say such a thing.

But after that my rear end started coming out more on the track and driving back home, I felt like I got 10-20 more horses. Could it be that the fuse was a little bad, but still worked? Making the fuel pump not working optimal before it finally just gave up? I've also had problems with drops in idle when the engine is cold, which now seems to have gone away.

I am thrilled to get the easiest and cheapest fix to the problem
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  #2  
Old 09-12-2007, 09:40 PM
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MatWiz MatWiz is offline
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Quote:
Originally Posted by Scany1980 View Post
......, I felt like I got 10-20 more horses. Could it be that the fuse was a little bad, but still worked? Making the fuel pump not working optimal before it finally just gave up? I've also had problems with drops in idle when the engine is cold, which now seems to have gone away.
Strangely enough, actually Yes.

The logical explanation is something like this: The fuse is broken, but the edges are very close to each other. Therefore still allowing the electricity to pass thru, but not as freely as before. An unbroken fuse is like a wire. It has zero resistance (zero ohm). If you have edges very close to each other, the electricity 'jumps' over the short distance in the air. The higher the voltage or the current, the greater the distance the electrons can 'jump' in the air. The familiar example to this is the spark plug.

Anyway, as a result, the fuel pump does not get a constant and full voltage all the time, so your engine is a little starved of fuel.

Another example to this will be, at home, if you replace a light bulb, when the switch is on. Just when you screw the bulb in, at the point that it makes the first contact, turn the light bulb a little out. You can hear the sparks inside, and the light will flicker and you'll get somewhat of a dimmed light. That is what your fuel pump was getting before you replaced the fuse.

Good catch though!
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  #3  
Old 10-02-2012, 09:31 AM
obermeyerdarell obermeyerdarell is offline
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Hi how are u?I've got the same problem with my 540i 94 model Bmw!where will I find this fuel pump fuse?my Bmw fusebox cover is gone,please help me I'm realy battling for three weeks now!thank you very much
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Old 10-02-2012, 09:39 AM
obermeyerdarell obermeyerdarell is offline
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Question fuelpump faulty

Hi there everyone!how are u?I'm in desperate need of help!one morning I started my Bmw 540i 94 model!she was idling for about 2min and stoped running!eversince she's been to a garage and could not help me to get her running again!I tried everything tested fuelpump,but no power on the wires going to fuelpump!what can I do and where must I check please?thank you very much
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  #5  
Old 10-02-2012, 11:33 AM
rdl rdl is online now
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Quote:
Originally Posted by obermeyerdarell View Post
Hi how are u?I've got the same problem with my 540i 94 model Bmw!where will I find this fuel pump fuse?my Bmw fusebox cover is gone,please help me I'm realy battling for three weeks now!thank you very much
I'm pretty sure that a '94 BMW 5 series would have to be an E34. The E39 series started production in 1995. Although I don't know for a fact, I'd imagine that the fuse boxes are different. Assuming so you would have more luck in an E34 forum. Best of luck.
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Old 10-02-2012, 11:58 AM
obermeyerdarell obermeyerdarell is offline
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The Bmw is a 95 model sorry my mistake
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  #7  
Old 10-02-2012, 12:52 PM
rdl rdl is online now
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In that case, follow this link to WDS: BMW's wiring diagrams, including part locators.

http://spaghetticoder.org/
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Old 10-02-2012, 03:15 PM
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Originally Posted by obermeyerdarell View Post
The Bmw is a 95 model sorry my mistake
Your car is an E34, not an E39. You should post your questions on the correct forum for the best response.
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  #9  
Old 10-03-2012, 06:44 AM
cn90 cn90 is offline
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Actually this is not uncommon at all.
It does not matter what car you drive, sometimes fuses build a tiny tiny amount of corrosion at the fuses' blades + connector interface ---> reducing current flow.

Very often, all people need to do is: remove the fuse and re-insert the fuse and that will do the trick.

Last edited by cn90; 10-03-2012 at 06:49 AM.
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