Today I went to check the in tank fuel pump as I've never been convinced it works. The external pump under the sill always sounds as though it's working harder than it should be (new fuel filter already fitted).
I planned to check the pump was receiving 12v and then hook up 12v to the pump to see if it will run.
When it came to disconnecting the plug (3 pin connector) to check for voltage I found different voltages at each combination of pins; 4.5v, 11.5v and 15v.... What's going on here?
A short circuit in the wiring somewhere?
I was hoping to find a simple ground and live but am now unsure what the 3rd pin is?
Many thanks
In tank fuel pump
Moderator: martauto
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Brianmoooore
- E30 Zone Team Member
- Posts: 49360
- Joined: Mon Jan 10, 2005 11:00 pm
If you only have the one three pin plug on the 'in tank fuel pump', then I don't think you actually have an in tank fuel pump.
The three pin connector is earth (brown), fuel level and low fuel switch. Strange that you are measuring a voltage on all three pins though. Brown wire should be 0.
The three pin connector is earth (brown), fuel level and low fuel switch. Strange that you are measuring a voltage on all three pins though. Brown wire should be 0.
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Jookeone
- E30 Zone Newbie
- Posts: 137
- Joined: Sun Dec 09, 2012 11:00 pm
- Location: Luton
Ah, that would explain it. So it would just be a level sender. Is that normal for a pre facelift 325i with just the one pump?
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Brianmoooore
- E30 Zone Team Member
- Posts: 49360
- Joined: Mon Jan 10, 2005 11:00 pm
I try not to get involved with pre facelift stuff (although there are early facelift cars with external pumps), finding the technology that little bit to primitive for my taste, but there are certainly versions with an in tank lift pump and an external pump, and versions with just the external pump. From what I've seen, I can't tie the different set ups to particular ages or engine types.