Bypass charcoal canister? Return Lacking Fuel System information

[xtrattitude4u]

I really hope that I don't still have a rich mixture problem. I did have a CEL of rich mixture a few months ago, but after replacing front O2 sensor and MAF it went away. I have also done a stage 0 tune and just about everything else that could fix a rich mixture problem. The only thing it might be is the injectors, but that sounds unlikely.

Just to minimize confusion, I have made this diagram to show how the system is connected. The hoses circled in purple are the ones I hooked together, providing the FPR with vacuum. I got at LEAST 50-60% better MPG after doing this. The slashed lines are fuel lines. I can't believe I finally achieved great MPG by accident, only to discover it's a false hope. Bummer.

Diagram2.JPG (30.25 KiB) Viewed 3837 times

[whoa]

Nice picture!!

I don't mean to be Johnny Skeptic, but are you sure that the fat hose goes to the tank? I would think it would just vent to the atmosphere, maybe through an electrical shut-off valve.

Edit: here is some evidence that that fat line should terminate at a shut-off valve:

[xtrattitude4u]

Nice picture!
I don't mean to be Johnny Skeptic, but are you sure that the fat hose goes to the tank? I would think it would just vent to the atmosphere, maybe through an electrical shut-off valve.

Thank You!I have edited it so as not to confuse anybody. I now don't doubt that it does, I had just assumed it went to the tank. Hence the question mark. That is the only questionable connection in the chart. All the other lines/connections/devices I have traced manually.
That makes sense, the small line is just a purge for the fuel tank with the FPR inline to receive ~atmospheric pressure. So how do I test the charcoal canister to see if it is working? I thought that because a vacuum line was attached to it and no vacuum came through, that it was clogged.

I guess I should connect it back the way it was, but now I have to continue my journey to find out why my fuel mixture is so rich, yet there are no CEL codes about it or anything else.
I can't believe that the car ran so well, that's why I'm so skeptical about it being too lean. It ran better than ever before, IMO.
Maybe the FPR is worn and provided closer to correct mix when having vacuum applied? IDK.

I think my purge valve might be damaged. It pulsates and turns on and off every couple of minutes. I can hear a loud ticking coming from it.

[whoa]

Maybe the FPR is worn and provided closer to correct mix when having vacuum applied? IDK.

Could be. Not hard to find that out. Check the pressure at the schrader valve on the fuel rail. Apparently it should be about 43.5psi all the time. I hear you can use a cheap tire gauge for that, if you don't have access to a fuel pressure gauge.

[xtrattitude4u]

Look at the bottom right of the first picture. See the red curved line? Inside that is where the brake? cable goes in. This same opening is visible in the upper left of the second picture. It's the best I could do with no lift and the extreme angles. You can also see the top of the muffler in the bottom left corner of the first picture and left center of the second picture, etc.

I just want everyone to be aware that there are 2 locations for the fuel pressure regulator for this vehicle. Most people don't seem to know.

So after connecting the hoses together the FPR has failed for sure. It leaks gas into the vacuum line. I can't be sure if it was already on it's way or if I helped it. After connecting to the canister am currently getting approximately 12-13MPG! This must be a record.

I need to get a new FPR but I haven't seen much info about the second type of FPR. Any word on aftermarket for this?
Does anyone think a bad fuel pressure regulator could ever cause that kind of mileage?

[thecheat]

I hate vacuum leaks. I also hate the evaporate system. Check your purge valve and fix or replace as necessary. Read my writeup here for testing and fixing the purge valve.

It is the same valve and it is probably starting to fail from old age. The most important thing is that the valve does not leak as it is usually closed and when it leaks it is a huge hole to let unmetered air in.

[xtrattitude4u]

Ok so connecting those lines together even temporarily is a terrible Idea. I left it like that because I was getting better fuel Mileage, but a couple weeks later my fuel pressure regulator started leaking gas into the vacuum line. Well, not the vacuum line, rather the vent hose I turned into a vacuum line.
I Put the hoses back were they were and am working on getting the FPR installed but am unable to.

This post has been a tremendous learning experience even though my original question is now mostly invalid.
The good news is I finally found out what was causing my horrible fuel mileage, and am now getting around 30mpg. My intake hose has been missing a clamp since I bought my car.

[xtrattitude4u]

It's been almost two years since my last post on this thread,
but I thought I'd conclude a few things for anyone interested.

The diagram shown is for a later variation of the motronic 4.4 system. If your fuel pressure regulator is not under the fuel rail above the engine and you have a non-turbo, you might have this system.

My charcoal canister was never clogged, I just didn't understand how the system worked. The charcoal canister rarely fails.
I thought there was supposed to be vacuum present at the fuel pressure regulator, but on this system the line connected to it only holds atmospheric pressure.

I destroyed my fuel pressure regulator in just days by presenting manifold vacuum to it. The seal inside of it tore and let raw fuel into the vacuum. When it reached my engine the car died instantly. No fun.

Do not bypass the charcoal filter. Be sure all the hoses are connected properly after working on this system.

I ordered a new FPR, but the fuel supply fitting was much larger than the original one. I discovered that every supplier I tried had the same part, and nobody had ever stocked the same part as on my car. After contacting Bosch directly, it turns out they superceded two part numbers into a single new one when they updated the part, eliminating the design with the smaller fitting. I did not have a heat gun at the time, so I'm not sure if it could potentially fit. (These fuel lines were heated and shrunk to the fitting when installed at the factory.)

I ended up getting a FPR from the junkyard that has held up two years now, however I recently noticed that some suppliers now carry two similar looking FPR's to mine, one specified only for 1998.
If that was due to my prodding, (I like to think so)I hope it helps someone down the road.

The vacuum path from the intake manifold to the charcoal canister shown at the bottom of the diagram would be the common place for an EVAP system leak, particularly the purge valve.

I replaced the vacuum lines in this area with rubber fuel hose for added durability, since these lines carry fuel vapors.
Just be sure the main hose connected to the manifold is thick enough and will not collapse under engine load.

I just need to vent . . .

[BEJinFbk]

Not enough posters close the book on their repairs.
IMHO, your latest update is greatly appreciated.

Thank You for providing the follow up !

[Kuda]

Hi guys. I just need to thank the poster for this thread and everybody with their valuable input. I have been searching for months for a solution to my 2003 S60 2.4T starting problem and high mpg. Not even the dealers could pinpoint it. 2 dealerships to be exact. So I will start to revamp the evap system this week cause there is absolutely nothing else to replace on this car anymore. Thx again