Bypass charcoal canister? Return Lacking Fuel System information

Post by **xtrattitude4u** » 07 Jun 2010, 15:32

98 s70 2.4l N/A
I have a clogged charcoal canister. As a result no vacuum makes it through to my fuel pressure regulator. What harm would it do to bypass the canister by connecting the two lines together until I can get a new one?

FCPEURO · Post by **FCPEURO** » 07 Jun 2010, 18:07

I don't think it would harm anything but I would think it would throw a CEL. Not a big deal considering it is either that or don't drive the car.

Post by **xtrattitude4u** » 07 Jun 2010, 22:24

The car drives fine without vacuum at the FPR. My only concern is fuel mileage.

Post by **xtrattitude4u** » 11 Jun 2010, 14:32

I connected the lines together for the 200 mile trip and got incredible mileage! I went from getting about 21mpg to getting about 36 mpg! I'll replace the canister as soon as I can.

whoa · Post by **whoa** » 11 Jun 2010, 15:05

How did you measure the mileage?

Post by **xtrattitude4u** » 11 Jun 2010, 15:27

I haven't gotten through a full tank yet, but I've been tracking, and recalculating the mileage at every two-gallon interval. at two gallons, I had traveled 80 miles, but due to the overfill and gauge fluctuation, I decided to wait before dancing.

After I had used 10 gallons, I had gone 280 miles, however at this point I had been doing about 100 miles of city driving, so it was a mix. Also, the weather was horrible on the way back, and it's mostly uphill. The first part of the trip was mostly downhill and all freeway. The weather was also excellent. During this leg I calculated my MPG to be about 36. The last time I took this same trip I could only get about 21 mpg at best during this stretch, and about 18MPG for the whole trip. So even if my calculations are off, I'm getting WAY better mileage than before. I'm getting better city mileage than my old highway mileage.

whoa · Post by **whoa** » 11 Jun 2010, 16:46

What I mean is, how are you measuring the number of gallons you are using?

So anyway I'm kind of confused here. Does the vacuum to the fuel pressure regulator really run through the EVAP canister on this car? If so, why? Isn't it just a vacuum-controlled valve?

Post by **xtrattitude4u** » 13 Jun 2010, 12:21

I'm using the fuel gauge because I don't have any other way of measuring it. I know by experience that my fuel gauge shows less fuel than actual at first, then gradually creeps up to the proper level. I assume this is so you don't run out of fuel.

My gauge shows just below half a tank after the trip, whereas before it would show somewhere near empty. I know my measuring techniques are not very precise, but the tests show that my mileage has gone from somewhere around horrible, to somewhere around the correct MPG for my vehicle. This is good enough for me to believe that I have found my main problem.

And yes to confirm, The vacuum line for the fuel pressure regulator goes through, among other things, the Evap\charcoal canister. I don't know why, maybe It's a safety thing. If the FPR fails it will let raw gas into the vacuum line and then the intake. Maybe the charcoal canister helps prevent or reduce that problem.

I still have gotten no response on whether it would be safe to just re-route the lines outside the box permanently or even temporarily. I'm assuming whatever side affects there were would not justify running the car without vacuum at the fuel pressure regulator.

Post by **jblackburn** » 13 Jun 2010, 13:00

I'm glad you figured out what the cause of it was. I'm on the path of trying to track down my bad gas mileage - I have already replaced both the ECT sensor and FPR, MAF, and I'm sure something else I'm forgetting all at different points on my car when they crapped out.

Where IS the charcoal canister on your car? Though we have a similar model, I think we may have a different emissions system, which is why I was hesitant to comment on any of your posts before.

But is it safe to run like that?

Permanently, no. The EVAP system serves to let off the fumes from the gas tank that build up. I'm rather surprised you haven't got a code for it before.

I left a gas can with the caps on once in the summer sun after filling it and deciding I'd mow the lawn the next day, and I guess it swelled up and burst. The charcoal canister/purge valve are to let the fumes out of your gas tank that build up in the heat, or in keeping fuel sealed in there.

Post by **polskamafia mjl** » 13 Jun 2010, 18:15

I know I have an 850 and you guys have s70's, but I found my canister right in front of the drivers side front wheel. I guess just look under each wheel and see if you can find the canister. lol