If you're having a similar problem with your P2 or P3 Volvo, this solution may be helpful...it worked beautifully for me and is quite simple.
First, a brief discussion of cause and effect. When you fill a large soda container with water and invert it, the water "chugs" out..."glug, glug, glug". However if you were to poke a vent hole at the top of the inverted container, the water will rush out smoothly...and fast! About 10X higher flow rate with venting.
When you are refueling your car, the gasoline you're adding displaces air in the empty tank. Where does the air go? By the time the tank is full, the air must all be gone. Answer (we're talking EVR-Phase 2 vehicles, e.g. California standard): Your fuel filler pipe has a parallel "refueling vent pipe" that brings air from the highest point on the tank back up to the throat of the filler neck. The gas pump nozzle has a tiny suction hole (no more than 3-4mm diameter), and suction draws the tank vapors to their resting place in the underground fuel tank. This completes a loop...a gallon of gas gets pumped up to the car -- a gallon of smelly air gets returned to the underground tank. This is how environmental engineers solved the problem of gasoline fume pollution. (When the fuel truck comes and restocks the gas station, it doesn't quite go back empty...it carries a truckfull of gasoline fumes (collected from 1000s of gas tanks) back to the refinery / distributor).
Here's the catch. Volvo engineers put a plastic mesh filter in the orifice where the Refueling Vent Pipe exits into the throat of the filler pipe (to protect from dirt intrusion??). Bottom line, 5 years into the life of my Volvo, this filter had become clogged with the residue from gasoline fumes passing thru it. This defeats the function of the vent pipe. Glug, glug, glug....as gasoline flows down the filler pipe, escaping air is fighting it coming back the other way. The inflow rate is drastically reduced.
So, the pump is delivering gas at a higher flow rate than it's chugging down the filler pipe, the level backs up in the pipe in just a second or two...and wham, the nozzle sensor decides the tank is full.
THE SOLUTION
All that is needed is to backflush (unclog) this plastic mesh filter.
Start by viewing it with a shoplight....you'll need a screwdriver to hold the throat flap open. You should see an orange disc about 6mm in diameter just an inch behind the flap, on the right side of the throat. If you were an M.D., it would be a "say ahhh" moment.
To clean the filter, you're going to spray it with Throttle Body Cleaner Fluid, and then having gotten your air compressor primed at 75 psi, after drenching the filter in cleaner, blast it with compressed air for about 30 seconds.
I had to add a 2" extender (heat shrink tubing) to the 4" plastic spray nozzle that comes with a can of Throttle Cleaner.
That's it!
This procedure worked wonders on my XC70. And, with the soda bottle analogy, you have a crisp cause-effect explanation for why a clogged vent pipe filter ruins the entire vapor recovery system concept, and has you standing there for 10 minutes trying to awkwardly push 15 gallons into your car 1/4 gallon at a time.
- RefuelingVentCleanout.JPG (150.84 KiB) Viewed 5740 times
