gldave

I'm participating in a "lemons" endurance driving event and I plan to use my beloved W208 Cab with 181K miles on it - got it for $1700.

I've purchased a 17 gallon fuel cell, fittings and pump to "transfer" fuel from the cell to the main tank when I press a switch. My BIG question is "where do I tap into the existing fuel system?

At the very least, I fairly certain I can run a line into the filler neck near the cap - that would essentially make it indistinguishable from a normal fill-up...maybe I'll have some weird pressure issues throwing the CEL.

But I've been looking at the schematics for the fuel filler and expansion tank. Could I connect into one of the evaporative returns? Or is that where the carbon filter lives? I'd be curious if anyone has disassembled that part of the car and has a sense of where I could tap in.

gldave

I thought I'd provide an update about this fuel cell project - it's going well. Once completed, the car should get close to 500 - 600 between fuel stops.

I finished the plumbing and after a quick drive, i'm happy to say it's not throwing error codes for the tank press. I removed the trunk liner, rear wheel, and rear wheel liner. Behind the wheel liner is a point that's easy to tap into - a small 1.75" rubber tube. I used a Summit racing bulkhead connector. I then used an AN-6 to hard-line adapter. The hardline goes through the bulkhead and attaches to a 70gph fuel transfer pump. From the pump intake, I've attached AN-8 and fittings that go into the fuel cell.




Here's mockup of the way the system is plumbed. Note that hoses will eventually be trimmed and the hardline extended. Only thing missing is the evaporation line - its going to be made from the leftover braided fuel line.





I removed the wheel and the interior fender liner. The rubber portion of the filler pipe is circled.





Removed the trunk liner and drilled hole through wheel well bulkhead.





Ran a 3/8" OD aluminum hard line to prototype positioning. This ended up NOT being the position - I ended up with less sharp turns because the rental pipe bender was terrible.