Universal Fuel Pump

[RPP]

I just began a restoration of a 1976 2002. The car was abandoned in an old garage and It will be a weekend project and I am having a blast. I have been working in the trunk area and relocated the universal fuel pump that was there when I purchased the car. I am a bit confused with the correct wiring because it is an aftermarket pump and could not find the proper BMW wiring diagram. The pump has two wires (black and brown). The black I grounded with the gas sender ground but the brown wires goes directly to the coil. That is how it was wired. Is that correct?  Also, the fuel line coming out of the gas vapor canister ends up inside the car cabin. Is that where it is suppose to go?

[Stevenc22]

The fuel pump needs any switch 12v source and a ground. The coil is a switched 12v source. Not where i would have wired it but it works. Also i would have ground the fuel pump with the bolt that holds the fuel pump to the sheet metal.

 

The fuel vapor canister runs through the cabin, comes out in the engine bay and connects to a carbon canister in front of the brake booster.

[jimk]

If the pump power comes from the coil, then it's power also comes thru the ignition switch.  If the ignition switch burns out, replacement will be a problem.  Search on ignition switches here and the issues will give you a headache.

[RPP]

Thank you Stevenc22 and jimk for your thoughts on this matter. Where else would you connect the + of the pump other than the coil. Sound like the coil would work but it is not the most suitable place for it. Stevenc22, I connected the - to the screw holding the pump to the frame. Thanks!

[jimk]

10 hours ago, RPP said:

Where else would you connect the + of the pump other than the coil.

Search your wiring diagram for connector 31.  It is the connector supplied on both Tii and non-Tii cars.  It is located under the dash, drivers side above the kick panel.  It is a fused connector just dangling.  A fuse block fuse protects it.

[FunkyLaneO]

The power to your coil is not fused and it is a resistor wire so that is not the best place to pick up power, the voltage will be low at your pump.  I would suggest you find the green/white wire with an open connector below your dash and use that, that is the one that was used for the tii electric fuel pump, that way it will even list the correct fuse on the sticker under you hood and in the owners manual..

[TobyB]

Quote

 I am a bit confused with the correct wiring because it is an aftermarket pump and could not find the proper BMW wiring diagram.

 

because there never was an electric fuel pump on a non- tii 2002.  So it doesn't exist.

 

Otherwise, add some sort of 'crash switch', be it inertial or oil light actuated or whatever, and carry on as per above!

 

t

uses the pressure from the spare tire as a fuel pump.

[Dave3x72tii]

I would never use the plastic fuel pipe under pressure. There are no barbs to help the hose stay on, it runs through the interior and I've seen the pipe crack and split which would flood the carpet with fuel. If the old metal return is there, I would use it instead. If not I would move the pump to the engine compartment and wire in a relay.

[John76]

2 hours ago, Dave3x72tii said:

If the old metal return is there, I would use it instead.

 

+1 Dave. 

Use the metal fuel return line, and possibly a Tii type fuel filter mounted next to the radiator to maintain a "stock-like" appearance.

However, most electric pumps like to push fuel, not suck it, so keep the pump in the trunk or under the car in front of the tank.

Here is a sketch of my planned e-pump installation...that I never did. I might reconsider, but skip the oil pressure safety switch and replace the optional toggle switch with a momentary push button. This would act as primer, or a carb "float bowl filler" to combat the fuel boil-off we see warm engines.

John

PS: Normally, the Brown wire is the ground, and the Black or Red is the +12V. Reversing these would make the pump run backwards!

As noted by FunkyLaneO, powering the pump from the coil would not give a full +12V.

[jimk]

14 hours ago, TobyB said:

because there never was an electric fuel pump on a non- tii 2002.  So it doesn't exist.

Connector 31 is there though.  I use it to power the cruise control.  The index to connectors identifies it as the fuel pump connector on the OEM diagram I have for a 2002 roundie.

BMW 2002 USA 12Volt 12 Fuse RoundTailight.pdf

[RPP]

John 76- This is totally awesome. Many thanks. One question: Where do I find the oil pressure Switch referred to in your diagram?

[John76]

Easy to find online. Try PegasusAutoRacing.com.  Part # 1109. 

There are two common type switches for electric fuel pumps: Oil pressure activated or Inertia activated.

With the oil pressure models, a third wire is connected to the starter to bypass the safety switch only during cranking, until enough oil pressure is established to keep the main contact closed.

The inertia type breaks the circuit if there is a sudden impact (crash). Pegasus Part # 1108.

John

PS: Mount the relay on the firewall, close to the oil switch. Use the plastic fuel line (the original supply line) as a conduit for the 12 AWG red wire to the fuel pump in the trunk. No need to run an extra wire through the cabin, under the carpet, etc.

[RPP]

Thanks everyone. This is the first time I post something as I am a first time owner of a BMW 2002. Your response have been fantastic. In the past, I have restored a 911, a Fiat Spider and an Alfa Romeo Spider. Nevertheless, this restoration project is by far the most challenging so far given the conditions of the car when I bought it. Is coming together and this COVID-19 lockdown has given me a lot of spare time. I will let you all know how it goes. Below a quick pick of the interior work.  Thank you.

[ray_]

BTW, in many cases (or perhaps all cases before mods and ethanol-laden fuels), a stock mechanical fuel pump is very dependable and less troublesome. As was said, BMW never saw fit to use an electric pump on non FI 2002s.

 

Cool project! Good luck with it! Where are you located anyway?

 

Cheers,