AWD Evap codes RESOLVED loose clamps

Post by **burnout8488** » 11 Jul 2013, 19:53

'99 S70 AWD - 162K

Codes:

P0440 - Evap System Malfunction
P0452 (Pending) - Fuel tank pressure sensor low

Symptoms:

Dropped rear subframe, can't find any broken hoses or evap leaks.

FPR on top of the tank is good, fuel doesn't come out of the diaphragm when sucked on.

Sniffed all of the lines, can't find any obvious vapor leaks.

Applied 9V to the fuel pump with the line connected to the car, everything pressurized, no leaks whatsoever on top of the tank.

Applied 9V to the shutoff valve, closes and holds air until 9V is released. (Used a bike pump to put some air into the charcoal canister using the EVAP line in the engine bay)

Applied 9V to the purge valve, it doesn't allow air through when closed, DOES allow air through when 9V is applied. Proper operation.

Question:

What sort of testing should I do now? Pull a vacuum at the line in the engine bay and see if it holds?

The system holds pressurized air just fine, maybe vacuum is a different story?

What about the fuel tank pressure sensor, do these fail or is that a common code to pop up when there is a leak or other malfunction?

Any chance the check valves for the lines going to the purge valve might be bad?

Thanks!

Pressure sensor to the left of the blue port:

Shutoff valve and fuel filter:

Post by **jimmy57** » 11 Jul 2013, 23:59

Seal all the open ports except one and then plug the vent line up by fill pipe. Use a cheapy aquarium pump and then look for leaks with soapy water. Don't neglect fuel cap as possible cause as it has overpressure and under pressure valves and they fail as well as the rubber seal to filler neck.

Spray EVERYTHING, the leak can be somewhere your eyes say can't leak.

Post by **burnout8488** » 12 Jul 2013, 00:25

jimmy57 wrote:Seal all the open ports except one and then plug the vent line up by fill pipe. Use a cheapy aquarium pump and then look for leaks with soapy water. Don't neglect fuel cap as possible cause as it has overpressure and under pressure valves and they fail as well as the rubber seal to filler neck.

Spray EVERYTHING, the leak can be somewhere your eyes say can't leak.

I like that idea, I'm going to have a fun day tomorrow for sure. It would make no sense if there wasn't a leak... there just has to be!

I cringe thinking how much this would have cost if I had to take it to a dealership. Yikes.

Post by **abscate** » 12 Jul 2013, 03:46

Do you have one in the Southern Tier? Ithaca does of course, but if you go there you should take it to Brumsted ...Ithaca Foreign Car

Post by **burnout8488** » 12 Jul 2013, 10:18

Yup, Serafini Volvo in Vestal, NY. But, nobody touches my baby unless absolutely necessary

I have heard of Ithaca Foreign car, I think my Aunt used to go there with her old 240/740 back in the day. Hopefully this won't come to that, it's just a matter of finding a leak I hope!

Post by **jimmy57** » 12 Jul 2013, 10:38

Unplug and inspect the tank pressure sensor connector (red yellow blk wires, shown in second pic on left on rusty bracket) for any corrosion on terminals.

Post by **burnout8488** » 12 Jul 2013, 10:58

Did that last night, they looked pretty good. Is there any documented test I could do with a multimeter? Maybe the operating specs are in VIDA or something? (Resistance vs pressure, etc.)

Post by **burnout8488** » 12 Jul 2013, 15:54

When I add air to the tank using a bike pump, it takes a ton of air but never actually builds any pressure. When I disconnect the pump, a large amount of air whooshes out. It's taking the air and holding the air, but not actually hitting 1psi and allowing me to compress it. The more I pump, the more air goes in.... and seems to stay there. Maybe I'll use an electric air pump to see if I can get it to crack 0psi.

Same goes for vacuum. I can pull a vacuum on the tank and it will create suction on the various ports, but it never actually builds *real* vacuum. Holds it all day, I can feel suction, but it doesn't get much more than that.

For these tests, I blocked off all the ports and isolated the tank. Even with everything else hooked up (canister, tanks) it behaves the same. Frustration.

Seems like there's a crack in the tank, but it wouldn't be holding such a high volume of air if that was the case I would think.

One thing I noticed is that the shutoff valve stays closed when there is vacuum applied to it. Shouldn't it be able to open itself under vacuum? Under very low vacuum it opens by itself, but 5 inHg (I think) seems to keep it stuck shut, not allowing it to vent.... Maybe that explains the P0452 pressure sensor "low" code?

Post by **burnout8488** » 12 Jul 2013, 18:24

Update: Used the air compressor. The gauge still didn't read above 0psi, but after running for 30 seconds I heard air pouring out of the fuel cap. This might be normal I'm thinking, to vent off excess pressure? Not sure exactly what pressure it's supposed to blow off at, though.

Post by **jimmy57** » 12 Jul 2013, 18:49

overpressure at 1.5-1.8 psi. The cap would open with about the same pressure as it takes to blow up a balloon. Prevents tank swelling.

The shut off valve should be open unless it is energized. If energized it will hold pressure or vacuum. Maybe not big pressure or big vacuum. The vacuum pulled on the tank to check for leaks is 3-5 inches of vacuum range.