WTF? fuel lines going to A/C line??

[JasonC]

I was working on my 87 and was checking every thing out under the hood. I seen two metal lines running at the top of the firewall and didn't think nothing of them. Till i checked the fuel lines and seen they was conected to those lines on the firewall and they ran over to the A/C line. What is this for? Vapor lock??? Is it only an 87 thing?

[erik325i]

The fuel lines do attach to metal lines, but they have nothing to do with the AC. They go under your car to the fuel pump...

-Erik

[JasonC]

I'm still confused. the gas line comes out from under the car on the drivers side from the pump/fillter, then runs over to that A/C line on the pass side fenderwell then goes back along the firewall to the FPR in the front. I'm sure it has nothing to do with the a/c like you said. But i'm still wondering why they ran them into the a/c line.

[erik325i]

In that case, I have no idea what's going on.

I have never seen that before.

-Erik

[rThor432]

It is the "fuel cooling" system. It was used on some, or maybe all E30s in the 1987 model year. The fuel lines run through the AC system to cool the fuel. BMW's thought behind it is that if the fuel is cooler, it will be more dense. And the more dense the fuel is, the more fuel you can fit in the combustion chamber.

So it should offer a performance increase in theory, but in reality it just makes removing the AC system a pain in the ass.

BTW you can search for "fuel cooling" and a few threads should pop up.

[AdamF 88iS]

There are a lot of early 80s BMWs with this feature.