Ghosts in the Toy

Sunday afternoon I opened up the shop doors and it was pretty warm out. I'm behind the 4runner and I hear what sounds like a pump running. I've got the fuel injection all torn apart so there's no battery in it, so it's impossible for anything to be non-static. So I thought... I walk around front and gasoline starts shooting out of a hose on the air chamber, which goes on top of the intake. I stopped it by loosening the gas tank cap.

To explain what happened I need to describe the fuel system. The fuel is pumped from the tank to the fuel rails, which connects to the injectors. The injectors need a constant 40 lbs of pressure so they use a fuel pump that will put out well over 40 lbs and have a fuel pressure regulator that bleeds off anything over 40 lbs. The excess is returned through the return line to the fuel tank. The return line actually runs to the bottom of the tank rather than dumping it in at the top to minimize splashing.

When the fuel in the tank sloshes around or gets warm, it releases vapors. These need to be vented before the pressure builds and causes something in the fuel system (like the tank) to rupture. It used to be they just had a breather line that vented this into the atmosphere. But this is an emissions vehicle so it's a closed fuel system. The vapors are vented through a 3rd line at the top of the tank (where vapors are highest) back to a charcoal canister which can store the fumes. When the motor is running it sucks the fuel vapors out of the charcoal canister and burns them in the engine. You may save a teaspoon of fuel per tank; it's more for keeping emissions out of the atmosphere (or your garage).

I had noticed when I removed the fill cap that air hissed out; there was pressure in the fuel tank. This means the venting wasn't working properly. My guess is it was also plugged from sitting so long. So when I opened the shop doors letting hot air in, the tank warmed up and the vapor pressure built up with so much pressure that it forced the gasoline through the return line to the air chamber. It was shooting out because I had a line unhooked between the air chamber and the pressure regulator. (I had to remove it to take the air chamber off.)

I started checking things tonight. The charcoal canister is almost plugged; may not be able to unplug it. Damn thing is over $300, so I'm REALLY going to try to bring it back to life. There's a rubber hose that comes off the tank that's got an obstruction in it that's so hard I couldn't break it with a screwdriver. A foot of 3/8 line is only a buck so I'll replace that. The rest of the lines seem okay.

Injectors:
I got those back today. He said they were the dirtiest he'd ever seen. Normally he cleans them within a day but he worked on these 4 days and couldn't get 3 of them cleaned. Said one was stuck open? He charged me full price ($15/ea); not sure that was fair since he technically didn't clean them... I hooked power to them and could hear them clicking so I don't know how bad they really are. I did verify I could blast some carb cleaner through the 3 "good" ones when they were energized. I ordered 3 more through rockauto.com, $123 shipped with the core charge.