348 vapor canister purge valve removal

Ernie, do you still have your damper pieces? I would rather weld that one than one that might be repairable. The jury is still out, so I don't need it yet, besides, and I hate to say it, but I am really thinking that I am going to find out that it is indeed my tranny, damn it! If it is my tranny, and then later a certain Phoenix mechanic and and one of his customers, a certain software company exec., come up missing, I swear, I was in Reno the whole time!

 

I changed it recently. There were very fine particles of metal attached to the drain magnet. Very fine, like from when I missed shifts (I thought) - nothing larger. This noise has been going on for over 10,000 miles.

 

Just had this happen on Sunday. Went to get gas an I could not remove the cap! I drove off to the Sunday gathering and had at least 10 people try to remove it. Went home and used some tape and channel locks to take it off. It sucked in air as I unscrewed it. guess I need some new canister valves.

--Mike

 

>> new canister valves

No, you probably don't. As Ernie and I have "discussed" ad nauseum, but finally to conclusion, the canister valves are not the culprit. Some versions of the 348 don't even have them - the intake vacuum is fully applied to the canister, and via the canister, to the gas tank, at all times.

More likely culprits are your anti-turnover valve and/or your canister. I would check your canister to make sure that you can draw air in through it (the gas tank is vented through the canister, so air must be able to come in through the canister or the tank will collapse.) If your canister is not plugged, then I would remove your anti turnover valve and test it for being plugged - probably just replace it. When I got a new one, I put an inline gas filter between it and the canister to keep carbon particles out of my new anti turnover valve. Then I got rid of the ferrari canister - it's a pos. I use one from a dodge neon that is twice as well made as the Ferrari one. The installation on the neon canister is a little frankensteinish, but it works fine.

If your canister valves were acting up, the symptoms you would get would be check engine lights.

 

The system will throw a code if it does not see continuity with the valve. Pull the connector from the valve and it will throw the code. Coil measures about 60 ohms.

By the way, the car does not care if the tank is not connected to the canister and it does nothing in a rollover, having the rollover valve spoken of earlier for this purpose.

I also agree with the notion that the engine vacuum cannot destroy the tank, as it would have to have the canister at the same negative pressure, as it is in-line. The canister on my 456 snaps together and is awfully flimsy; the ones in the pictures don't look much more robust.

 

>> the car does not care if the tank is connected to the canister.

You're right about that. The reason it is so connected is so that fumes in the tank on a hot day will be collected by the canister instead of released into the atmosphere. Then you get to burn them in your engine. Seems like good sensible pollution control to me - involves no inefficiency to capture and pays for itself on the out-go.

However the jury is still out on what was plugged that caused Ernie's tank to collapse. Either a plugged canister or a sticky turnover valve would do the job, I think.

>> valves
You will also get CELs if the valves are not functioning correctly, even if, electrically, they are present. If they are open all the time, our version if the ECU will detect out of bounds mixture conditions and throw a CEL. N.B. I am not speaking from certain knowledge, as I have no access to the Motronic source code. I make inferences as a result of observations of my car's behavior. One of my valves was flaky, though electrically present. I was getting CELs, but they had a different pattern than if I disconnected the valve. I replaced both valves with a matched set, and the CELs went away.

 

Maybe a bad connection that cleaned up with the new parts?

All I know is that when I put in a resister to mimic the valve, the computer was happy - no CELs. I was able to make the car throw the code by disconnecting the resistor on each side.

Note that this behavior is consistent for both the evap valves and the valves used to port engine vacuum to the air pump isolation valves.

The system (ECU) will not know the valve is open or functioning when energized, only that the coil is there (not open) and (possibly) that it is not shorted. On the second, I tried vaues of resistance that were as low as I dared, and the ECU did not respond negatively, leading me to believe there is a current limiting circuit, but no threshold for some sort of BIT. Did not measure current when doing this, so this is empirical at best.

 

You were not experiencing gas tank vacuum, or, at least, you don't state that you did. But, that is what we are talking about here.

A completely *electrically* non-functional solenoid, yes, throws a CEL, but it is much more binary than what one observes with a functionally flaky valve.

 

Thank you for posting this. I'm in a 97 F355 GTS and the pressure is intense. I'm asking everyone that will listen what it could be. Maybe it's this, I was told Bosch sells the Roll over Valve for about 30-50 bucks and I'm having no luck finding this...

thanks for this post !

 

You can pull your purge valves out of the circuit and run full purge at all times. Nothing will happen to your tank. (Look at the parts book - some models didn't come with purge valves.) The failure points are the canister itself and the rollover valve. Only those could cause the gas tank deformation Ernie experienced.

It's simple: the tank's vent is at the canister via the rollover valve. If the rollover valve is stuck or the canister is plugged, then you don't have a tank vent. *That's* when you will see a deformed tank!

Check your rollover valve, use your lungs to draw air in it from the bottom to the top. It should resist but be able to be overcome. Flip it over and it should not flow at all. Then make sure that you can draw air in through the tube connected to the canister.

I'm not saying that your purge valves can be ignored. They are part of the system and should operate correctly. If they don't open, you won't clear gasoline out of your canister. If they don't close, you won't be operating at optimum spec in closed and wide open throttle. (The purge valves are only supposed to be open when the engine is operating in closed loop mode.)

Are you sure that you have *negative* pressure? On hot days, I have a lot of positive pressure, and my system is working perfectly.

If you need a new rollover valve, you can get one from England for about $100. The link is in an earlier post of mine.

 

For the record: Brian Crall rebuilt my gearbox, and the noise is gone. Also the car drives a thousand times smoother at low revs. I am so frick'n happy!

 

Good to know he's still out there doing quality work.

 

Nothing. I saw up above where I was grousing about the damper repair not fixing the noise, so thought I'd close that chapter.

Back to our regularly scheduled thread...

 

He does know how to fix stuff. Did he say what exactly was wrong or was it just time with worn out parts?

 

There were a number of problems: loose ring nuts and etc. But the biggy was the [can't remember the name] shaft that has a splined end and mates with a splined hole - the shaft that feeds power from the clutch to the, is it the layshaft? Mine had huge amounts of play, and that was the source of the banging.

Anyway, he has a guy that welds the two together, and no more noise, plus smooth acceleration from 1500 rpm in 5th.

Now, all I need is a proper major and an hvac refurb, and I'm a pretty happy camper. Not done, by any means, but happy, yes!

 

Not sure what you mean perhaps you mean the common problem of the hollow clutch shaft gear causing runout on the splines = gear noise. Welding this gear to the shaft is a cheap fix to avoid a 3K parts sourcing. If I got you right, I've welded 3 of those so far and replaced 3 of those in total so far. One on my gearbox and it never broke again even after racing it. Some call the 355 small spline clutch shaft an upgrade. I say just put the 348 large spline one on correctly and there is no problem. PM me on the hvac if interested.

 

Ernie...you rock!

 

What's the going price for a 348 fuel vapor canister?

 

Who has it for CHEAPEST I should have asked??

245= ~ $415 US....that is a better deal than I have found. Where can I order that?

I thought it was upper $400 range at Ricambi recently....then noticed over $800 today...I must have looked it up wrong a few weeks ago.