I was doing injectors and regulator swap on my friends IROC the other day. His car has been running crazy rich for the past 2 weeks, practically tripping over itself. I told him not to drive the car, but you can probably guess how that went. So the oil was completely saturated with fuel.

Anyway, so I got around to doing the work, and when I took the plenum off, to my surprise, a good amount of fuel poured out of it. How can this happen? the injector is right before the valve, how the fuel made it up there is a mystery to me. The only thing I can think of is through the PCV.

Doesn't really matter now, I'm just curious as to why it happened.

 

Fuel PSI regulator diaphragm is bad.

 

Yeah it was old and cracked when I took it out. The previous owner had the entire upper end of the motor apart, new upper and lower intake gaskets, painted the crappy original injectors, etc. Have no idea why he didn't replace the diaphragm while he was in that far.

Everything is back together, like I said, just wondering how fuel got up to the plenum.

 

As TTOP350 posted through the FPR vacuum line is common. The other is through the CCP system. Swap the return and vent lines at the tank and the CCP canister fills with fuel.

RBob.