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Old 04-05-2011, 11:31 AM   #65
BMWMac
Registered User
 
Join Date: Mar 2011
Location: Salt Lake City, UT
Posts: 61
My Ride: 325i
Quote:
Originally Posted by vitaladeel View Post
this might be a stupid question but what is the function of fuel sending unit? does it sucks fuel from one side of the tank to its own side? How to check if they are bad or not. And what about the fuel pump with sending units, i have seen those too. Thanks
Check johnnatalie's post above. I believe that is the answer. The fuel sending unit is really a fuel gauge to tell you when the fuel is low. I'm not sure why there are two of them (one on each side). If you buy a new fuel pump, it should have integrated into it a "fuel sending unit". Someone correct me if I'm wrong (which happens frequently).

I just replaced my fuel pump last night. Thanks to this write-up, it was honestly a 20-30 minute job. Here is my only bit of advice. When I disconnected the fuel line from the pump, it had some built up pressure and sprayed a bit on my back seat. There wasn't a lot of fuel, but the pressure made it spray everywhere. Sprayed worse when I tried to put my thumb on it. I would recommend wrapping the connection in a rag so that when you disconnect the fuel line, it sprays into the rag.
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