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-   -   96 740iL - Fuel Pump and Wiring Problems (

randyw419 08-25-2012 03:59 PM

96 740iL - Fuel Pump and Wiring Problems
To start off this is my 1rst BMW. Its a 1996 740 iL with 160k miles and needs a lot of work. I considered replacing the engine but that may not solve the problems Im having. I put a new battery in but there is acid in the tray. They previous owner put what Im assuming is a stereo system and blew the alternator. Anyways it fires up with starting fluid and dies. Ive put together the engine part by part. Anyhow I disconnect the hose at the fuel rail and dirty old pump out. I put new fuel and replaced the filter. The filter had no pressure so when I checked the pump it isnt switching on. Keyed on position 2 only 1 wire has 12v and that a constant in any position. I found 3 relays in the engine compartment, 3 above the battery in the trunck, and this is where I have a major problem. In the cabin I have no center console components such as a rdio, climate control ect. I have found 3 more relays, 1 tall black relay, there is a plug hanging down with no resistor. Its inline with 2 thin gauge wires. Whats worse I have 2 wires with eyelets that are attached to nothing. 1 is red/blue. Right now Im just trying to figure out why I the fuel pump isnt kicking on. I also heard that it might have an inertia switch. Im over my head right now, but this car just grows on me and I hate to get rid of it. Any suggestions on any of these issues?

joyism5 08-26-2012 08:14 PM

Have you checked the fuel pump relay for corroded pins? Can you hear the fuel pump engaging? The fuel pump relay is shown in the video min 1:10

If you don't hear the fuel pump engaging probably the fuel pump is bad. With a voltmeter, if u check, do you have continuity between the pins? You could jump the fuel pum from the fuel pum relay...
I would remove the fuel pump and check the fuel pump sump for sandy corrosion, If the car was sitting for a while without being started for sure it has a lot of dirt around.

randyw419 08-29-2012 02:05 PM

Ill check it out tonight to see if its working.

randyw419 08-29-2012 08:39 PM

Sounds like the relay is working so Im going to jump the termals to see if pump comes on. I also found the two hanging wires at the other relay location under the passenger side dash are from a relay. Just have to find which one goes where and screw them in.

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