M42 engine swap

[soma]

I'm currently putting a M42 engine into a 316, I've been told the fuel system was different from the old M10, so I'm switching tanks. I was planning on finding a supply fuel pipe and a return fuel pipe because of the pump now being in the tank itself. But I've found a third fuel pipe...

Could any one give me some advice or explanation on the fuel system of the 318is...

(Could it be to supply air pressure within the pump?)

Thankz...

Thomas

[Gunni]

your 316 is a carb car?
of so it should only have one pipe and your M42 car may have 3 pipes, one for feed, one for return and one for the charcoal cannister,

you need to feed the return back to the tank , you shouldn´t need to switch tanks,
find a fuel pump holder that has a return and feed, put a line from the return back to the front and connect it to the top line from the M42

[soma]

yeah, it was a carb, with only 90bhp so I got rid of that poor thing ...

now for the 318is, the fuel pump is situated in the fuel tank, so I think I do have to switch tanks (there is also one extra loom of electricity to the 318IS-tank.) So at the moment I have the feed line, the return line, and where do I attach the third one to the tank?

thankz for the response

greetz

Thomas

[Gunni]

you shouldn´t need the 3rd one,

[Brianmoooore]

Third "fuel line" (the rusty one) is the vent pipe from the fuel tank, via the vapour collector tank living high up in the rear right wheel arch. It goes from the back to the front of the car, and on most UK E30s (no cat), it ends in a short rubber hose tucked inside the reinforcement for the front left suspension turret.

[soma]

thanks a lot, now it all seems to make sense...
So Where should the vent pipe be attached to the engine?
I happen to know the freakin' vapour collector tank pretty well, I personally think it's a mistake by BMW, placing it there, it's a breeding nest of rust... Happily for my project it was just one of three breeding nests, but still... I keep saying the german steel is impeccable, but there constructions are sometimes risky (lower corner of front wheel arch are four layers of steel welded onto a little square... Talkin' about a mixture of steel, oxygen and water there...) Hasta la rusta ... Viva La Rutex!

thanks for the advice...

thomas

[Brianmoooore]

thanks a lot, now it all seems to make sense...
So Where should the vent pipe be attached to the engine?
thomas

If it's a non emissions equipped car, then it doesn't connect to the engine at all - ticks into the turret as I said above.
On emissions cars it goes to a charcoal canister then a solenoid valve ( unused connector hanging off the loom to the AFM ) and then to the inlet manifold (short blanked off pipe off the manifold on an M40, stub pipe behind the TPS on a M20, and can't remember on the M42.)