Pressure

#1

Opened the gas cap after the race today and had a massive pressure release along with a nice spray of fuel all over me. First time that’s happened. Clogged vent line? Something else?

#2

Do you still have the charcoal canister? Is the rest of the venting/vapor recovery system above the right rear wheel still intact?

#3

Chris cobetto had this happen at nats I think. If you can talk/email/Facebook him maybe he can help you out

#4

Jim Levie and Rich Bratton would be two guys to talk to. They’ve done more with the fuel tank than I have. That said, the easy thing to check is the vent line that goes forward into the engine compartment. It used to go to the charcoal cannister, as Andrew mentioned. Take a look at how that line is capped off. It should be capped in a way that can breathe, like with a little filter or something.

Then there’s the vent system mentioned above the RR wheel, but I’ve never looked into that so I don’t know how it’s plumbing works. RealOEM has some nice diagrams of it tho.

#5

Charcoal canister is removed and a small filter is attached. Going to replace that filter and blow the line out with air. Yes the recovery system is still intact. What should I do with it?

#6

It’s definitely a problem in your vent system that could be 1) plugged forward vent line, 2) a melted or kinked plastic line above the fuel tank (inspect above the fuel pump), or 3) a kinked/plugged/melted line going to the overflow reservoir inside the passenger rear tire well.

#7

Keep the vapor/expansion tank system, but inspect the associated hoses and lines for blockage or damage. I also suspect blockage somewhere along the venting path from the gas tank, to the expansion tank, to your breather filter. As long as this path is clear the gas tank shouldn’t develop pressure or vacuum.

My car sat for a while without a gas tank. The neighbor’s honey bees plugged many of the open gas tank and vapor lines with mud. I went through the entire fuel system and cleaned and replaced many lines. The exercise forced me to become familiar with the expansion tank plumbing. I was planning to remove it, but changed my mind once I understood how it worked. I personally think it’s a helpful system and see no benefit in removing it. I know people who did and then had issues with full tanks dumping gas and vapors inside the car.

As for the charcoal canister, there’s no harm in removing that. I also removed the hard line under the car and put my breather filter near the fuel filter. I believe euro E30s without charcoal canisters are set up this way.

#8

Update: checked all the lines and they appear to be clear. Ran some air thru them and no crud came out. Other ideas? Could the exhaust be heating up the fuel too much? Never had that problem before AFIK.

#9

When you checked and cleared all lines did you check all the vent lines?
If not remove the right rear wheel and remove the sheet metal cover that protects the rubber fuel vent lines. check for a crushed or crimped hose/tube. I have seen this prevent car from taking a full fuel load by maintaining a large air bubble instead of venting.
Good luck.