Anyone wise as to the ways of the evaportive control system?

[Synisalo]

Hello all again... the saga continues...

I have been, since I bought my Z, getting the dreaded p0455 Code from the OBD port. Gross leak/ No flow.

What I need to know is, probable causes, the components of the system, and their locations. I already replaced the gas cap, as that seems to be a common failure item. One thing I did notice, is after driving a while, then stopping for gas, there is a distinct sound of air rushing into the tank, and a strong smell of gas.

Any input would be greatly appreciated.

Pertinent stats:

1997 Z3 Roadster, 62k on the clock, 2.8 5spd.

Runs great.

Was in a catastrophic flood last year, and I have been revamping it since I bought it *CHEAP* .

[Synisalo]

Wow...no one?!?

[Randy Forbes]

The definitive test, is to do a smoke test. You introduce "smoke" from a smoke generating machine into the fuel filler, and see where the smoke comes out.

I can tell you where I think the leak will be; in the maze of plastic tubing on top of the fuel tank. Soy beans is a component of the pvc/plastic recipe, and rodents love to chew on them.

Flood means critters looking for high ground, and once they settle in, they like to graze...

Edit: food for thought...

[illiano]

The definitive test, is to do a smoke test. You introduce "smoke" from a smoke generating machine into the fuel filler, and see where the smoke comes out.

I can tell you where I think the leak will be; in the maze of plastic tubing on top of the fuel tank. Soy beans is a component of the pvc/plastic recipe, and rodents love to chew on them.

Flood means critters looking for high ground, and once they settle in, they like to graze...

I'm confused, a smoke test through the fuel filler? Perhaps you meant fuel filter, but that doesn't make sense either. I run my smoke tests through the air intake hose, just past the MAF.

Tony

[Randy Forbes]

It's the easiest place to test for evaporative loss; the air space above the fuel level is open to the separation chambers, etc.

When I do a supercharger installation, I ALWAYS test the intake tract for leaks, and usually find one!

[illiano]

It's the easiest place to test for evaporative loss; the air space above the fuel level is open to the separation chambers, etc.

When I do a supercharger installation, I ALWAYS test the intake tract for leaks, and usually find one!

Woah never knew that. So you run smoke into the tank and the smoke will come out in the engine bay?

[Randy Forbes]

Woah never knew that. So you run smoke into the tank and the smoke will come out in the engine bay?

Two (2) tests; evaporative loss from the tank filler (usually leaks are in the maze of tubes shown in the picture a couple posts back). Stereo installers are also prone to drilling holes in the top of the chambers/tubes.

The other test, when warranted, is to test the intake tract for leaks. Superchager installs, due to the many couplings, are one time that I always check for leaks__comebacks are unacceptable to me.

[Z3speed4me]

Randy, how would one even think of repairing that without pulling the tank?
Ever since FI I have had a random leak code every few weeks, clear it and goes away, but I still plan on finding it one day.

[rf900rkw]

The fact that it's building pressure (or vacuum) in the tank makes me suspect there is a blockage in the system. Possibly a fouled charcoal canister, or s stuck purge valve or shutoff valve.

[Randy Forbes]

Randy, how would one even think of repairing that without pulling the tank?
Ever since FI I have had a random leak code every few weeks, clear it and goes away, but I still plan on finding it one day.

You can think about it all you want, but there's only one (1) way to access the top of the tank. The exhaust and entire rear suspension assembly must be removed before the tank can be dropped out (I recommend running the fuel level down as low as possible beforehand__less than 1/8 full).



There's a very comprehensive set of pipes, all available under one (1) part number, dependant on the year/VIN of your car. This is the set for LJ80131 (01 S-54 Rdstr):

[Synisalo]

The fact that it's building pressure (or vacuum) in the tank makes me suspect there is a blockage in the system. Possibly a fouled charcoal canister, or s stuck purge valve or shutoff valve.

Thanks for all the valuable input folks.

Where would said purge vale, and shut off valve and charcoal cannister be located? There is definately a pressure/vacume being created, which tends to indicate a blockage rather then a hole.

Thanks for the pics randy, now I know what that mess looks like, and the thought of removing it is giving me hives. I will investigate all other possibilities before even thinking of removing the gas tank.

[rf900rkw]

The charcoal can and the shutoff valve are just in front of the rear subframe on the left side. The purge valve is in the the engine bay, pretty much straight below the MAF.

[Synisalo]

Awesome. Thanks a bunch!

[Telecomtodd]

I'd bet the charcoal can is full. The hoses can become disconnected if someone or thing has been under the car. But you sound sure it is a blockage - it may be the can.

One note, if you do replace the can, buy the stupid $24 mounting bracket for it. It is designed to go in once, and for the life of me I couldn't get it to pull back out of its mounting spot - I ended up having to use my saws-all to get it out. The new one bolted right in and it was simple to put the new can right into place.

BTW, I had the slow evap leak code, your problem's cousin. Bought a new gas cap too, what a waste of money, LOL. Paid about $300 for the can and $24 for the mount from ebmwparts.com, one of the vendors here.

[Synisalo]

An update...

I finally had time and was willing to not drive on a beautiful saturday afternoon, and yanked the cannister. Easy removal. When I disconnected the bottom hose, a load of water came out. Not a good sign, although as I stated, it was in a terrible flood. So I pulled it, blew it all out, made sure the shutoff valve was working correctly,Blew out all the lines and reinstalled. Reset the codes.

Here's hoping that cures the problem.

More updates as events warrant.

[tohbi]

Soy beans is a component of the pvc/plastic recipe, and rodents love to chew on them.

Flood means critters looking for high ground, and once they settle in, they like to graze...

Edit: food for thought...[/img]

hahaha! so right, randy. a packrat chewed up the wiring and hoses on my ranger. cute little critters. grrrrr.

someone wrote a charcoal canister cost $300 [!]. seems like this could be easily rebuildable? opinions?

[Synisalo]

Cannister looked to be a sealed unit. No obvious way to disassemble it , and more importantly, REASSEMBLE it. I mean, lets face it. a sawzall has the ability to disassemble a lot of things.

[amancuso]

Cannister looked to be a sealed unit. No obvious way to disassemble it , and more importantly, REASSEMBLE it. I mean, lets face it. a sawzall has the ability to disassemble a lot of things.

Thanks for posting back up! Let us know what happens. Have you hooked up with any of the Z Clubs in the area?

[Synisalo]

Update...

Due to an overwhelming work load, and replacing my kitchen, I have not has much time to play with this problem...

However, I did find a used Charcoal Cannister in ebay for $80. It was an easy swap out. Once I had it installed, I used the ever popular sawzall to cut the old on in half. Interesting innards, all rusted, and water soaked. The new can was a good couple pounds lighter then the soaked one.

I reset the codes and went driving...

Now then, the CEL would come on after about 80 mi, rather consistently. After replacing the can, I drove for more then 240 Mi. I thought " YAY!" fixed it!

No sooner did I have that thought, then the CEL came back on, same code. So, Fixed, its not, although the sound of air rushing into the tank is gone now.

There isn't an shop near me that can do a smoke test. So the next step is to use my fiber optic camera and try to see if there is anything amiss topside of the fuel tank.

I have an inspection coming up in two months. gotta try to get it sorted before then Thankfully, if I spend more then $150 on the problem, and it cant be solved, I can get a wavier.

[Synisalo]

Problem resolved!!!

After extensive research and testing, I found that the pressure sensor on the top of the tank had gone bad. All other parts of the system were operating normally, and it held a good vacume.

Since we all know whats involved with replacing the sensor, I decided to take a different approach. Basically, bypassing it.

After a load of internet research as to how those systems work, and with the help of a friend who is an electronics wizard, I hacked into the wiring harness near the DME, and installed a 10k Potentiometer into the circut.

This can be adjusted to provide the correct voltage to the DME, simulating a functioning Sensor. The correct voltage is 3.25. This falls into the range that the DME is looking for when it conducts the Evap tests. Been in for more then a month now, and several tanks of gas, and no CEL

YAY!

Got it inspected this week, and the emissions passed perfectly.

Now that that problem has finally been addressed, and that being the last of the mechanical issues.... now I can finally start thinking about the sound system upgrade.


-syni

ps, if anyone needs more detail about this mod, feel free to drop me a line.