EFI Fuel Pump Location

[decoupe]

CS to EFI conversion project for the winter (here already). I've picked up a complete 1981 528i TB (thanks to Jeff in Edm, AB) and manifold assembly that I bead blasted and am in the process of overhauling with fresh OEM parts. The La Jola Indy pre-pump, sending unit and electrical harness should be here this week. The cars are put away for the season with the CS on the hoist and I'm doing what ever I can with my left hand in a cast in preparation so some questions.

I've searched six pages after typing Fuel Injection an found some good tips but no mention of alternatives to the stock fuel pump location in front of the passenger half shaft and alternatives to the stock fuel line route.

Pros and cons of either in the trunk or in the engine compartment?

Both of these locations would permit better access/ease of installation and stay much cleaner (if my 200k 320i was any example - looked like a barnacle). Trunk would likely be noisier then the stock and use up what little space there is but is closer to the tank. Engine compartment provides all in one place access, noise not an issue, might be able to eliminate the surge tank with the proximity to the injection manifold. I'm assuming that these things push or pull equally - shouldn't make a difference.

I read one post (BonitaCS ?) that mentioned running the fuel line through the cabin rather than under in the stock location. Anyone have any experience going this route and able to provide specifics?

Thanks, subject icon is a picture of my thumb - post op.

 

[Sven]

Here is where I put the main fuel pump: just in front of the fuel tank, below the trunk plywood floor. There is enough space to wrap the pump with some foam. It is held in place with zip ties to a plastic mounting base. I cannot hear the pump once the engine is running.

Part #16141179232

 

[decoupe]

FP in Trunk

Sven:

Looks nice and neat with everything accessible. Did you eliminate the surge tank from the system?

Doug

 

[AndyM]

As long as you are using the pre-pump, the main pump can be mounted just about anywhere in relation to the top or bottom of the tank and no need for the surge tank. I'd keep it at the rear of the car. Sven's set-up looks pretty clean and is more accessible than the stock location. I'd keep the fuel lines out of the cabin for safety reasons.

 

[Sven]

Doug,

Yes, there is no surge tank in the system. There probably should be. I have not had any problems thus far, but if you are running with a fuel tank near empty and take sharp turns....

I believe the surge tank needs to be mounted vertically. Perhaps against the rear seat wall in the trunk space. Or, maybe drop it through the rear center corner of the spare tire well floor. I would rather not have it visible in the trunk space. I will have to consider it some more if I decide to put one in following restoration work.

 

[2800csm5]

Fuel Pump

On both my coup's the fuel pumps are mounted in __[ ]__ brackets above
the passenger side half shaft. The fuel filter is mounted two inches in front
of the pump. No noise, works great over ten years. Coup (1) S38 M5 conversion
coup (2) euro 635i conversion.

 

[decoupe]

Fuel pump location

Thanks for the advice. Compared to the Carter Rotary electric pump I have this should be quieter regardless of where I put it. Surge tank seems optional but I get the value in having one if you miss filling up in time.

Doug