Charcoal cannister buzzing duration?

[petegangies]

Hi all..

How long should the buzzing from the charcoal cannister last after turning off the vehicle? Mine goes for several minutes.





Is the vent hose underneath supposed to swivel around?

Thanks
Pete

 

[clx16]

It isn't really about the duration... they aren't supposed to buzz.

 

[clx16]

There is a ball in there that should work like a check valve. It sounds like to me that the ball is vibrating so maybe it's just dirty and not sealing well enough.

 

[BTLSHP]

The lower hose is designed to pivot, no issue there. The buzz does sound like the ball in the valve. It is a pain to get to. Mine had varnished itself to a perfect seal. I am kind of curious why yours is not equalizing pressures as you drive.

 

[doc_random]

Does the petrol tank gush fumes when opened just after driving? My charcoal canister was not venting properly and the system (tank+cannister) would build up pressure. I had a hissing at the charcoal cannister from the pressure venting there. Worse in warm weather and worse with low fuel level.

 

[petegangies]

Does the petrol tank gush fumes when opened just after driving? My charcoal canister was not venting properly and the system (tank+cannister) would build up pressure. I had a hissing at the charcoal cannister from the pressure venting there. Worse in warm weather and worse with low fuel level.

nope, not at all.

The lower hose is designed to pivot, no issue there. The buzz does sound like the ball in the valve. It is a pain to get to. Mine had varnished itself to a perfect seal. I am kind of curious why yours is not equalizing pressures as you drive.

how do we know it's not equalising pressure as I drive? Because of the buzzing?


Also, I accidentally knocked off the vacuum hose to my fuel pressure regulator yesterday while working on the car. I noticed a bit of fuel come out of the hose when I pulled it off to replace it with a fresh vacuum hose for a tighter fit. Could these be related?

 

[BTLSHP]

nope, not at all.


how do we know it's not equalising pressure as I drive? Because of the buzzing?


Also, I accidentally knocked off the vacuum hose to my fuel pressure regulator yesterday while working on the car. I noticed a bit of fuel come out of the hose when I pulled it off to replace it with a fresh vacuum hose for a tighter fit. Could these be related?

As far as I can tell the EVAP system should constantly equalize pressure. What varies is the movement of fumes to the intake.

The line from the FPR is a return line to the tank

 

[petegangies]

As far as I can tell the EVAP system should constantly equalize pressure. What varies is the movement of fumes to the intake.

The line from the FPR is a return line to the tank

As I understand, the vacuum hose off the FPR is repsonsible for adjusting fuel pressure in response to changes in vacuum in the intake manifold. So having knocked it off would have caused it to run at higher pressure. Though this was only for one 40min drive, before I discovered and reconnected it. My question though, is a) why was there traces of fuel in that vacuum line, and whether this has any relation to whats going on with the charcoal cannister.

I must admit, I'm not super up to speed with how EVAP systems work, only the general concept, so appreciate any guidance.

Some bits n pieces from the FSM:

 

[clx16]

I can't remember the thread but you might find the one where people replace the canister with the Pontiac one. I believe some people mentioned fuel in the lines indicating that it saturated the charcoal or something. Either way I don't think you should see actual fuel in it.

 

[petegangies]

I can't remember the thread but you might find the one where people replace the canister with the Pontiac one. I believe some people mentioned fuel in the lines indicating that it saturated the charcoal or something. Either way I don't think you should see actual fuel in it.

It's not my charcoal cannister with fuel in it, it was the vacuum line off the fuel pressure reg. I don't have any gas tank issues or fuel smells, just the buzzing noise from the canister after I turn the vehicle off. Since they're NLA, I'd rather not just replace the canister for the sake of it, if this buzzing noise isn't actually a problem..

 

[clx16]

I probably wouldn't replace it.

 

[petegangies]

I probably wouldn't replace it.

I'll do the FSM tests and clean though!

Now I'm working out whether I should replace the fuel pressure regulator...

 

[CharlieS]

Are you sure it is the canister not a relay in the box right beside it? The canister is stupid simple, and I have trouble imagining what could possibly buzz.

 

[petegangies]

Are you sure it is the canister not a relay in the box right beside it? The canister is stupid simple, and I have trouble imagining what could possibly buzz.

you're absolutely right, I'll have a much closer look and try and narrow down exactly where the noise is coming from... certainly sounded like the cannister to me, but as you said, there's a bunch of relays beside it.

 

[BTLSHP]

I can't recall where the ball valve is on the canister - but if you put you fingers on each of the in and out lines where they become aluminum this buzzing in your video should be a vibration you feel. That said the FSM tests are dirt simple. I am took a risk with mine an rebuilt it removing the little ball and spring. It has to pass and emissions inspection test this July.

My ball valve was varnished shut and there was no flow and lots of hissing at the gas pump. I hope my rebuild is unnoticeable for emissions. My hissing at the pump is entirely gone.

Good luck

 

[petegangies]

I can't recall where the ball valve is on the canister - but if you put you fingers on each of the in and out lines where they become aluminum this buzzing in your video should be a vibration you feel. That said the FSM tests are dirt simple. I am took a risk with mine an rebuilt it removing the little ball and spring. It has to pass and emissions inspection test this July.

My ball valve was varnished shut and there was no flow and lots of hissing at the gas pump. I hope my rebuild is unnoticeable for emissions. My hissing at the pump is entirely gone.

Good luck

thankfully I only have a short puff when I open my gas cap.. which I'm pretty sure all our cars do.

I'll definitely do the FSM tests and the clean they specify. I've got a stethoscope, so I'll try zero in on the location of that buzzing noise! The noise is much worse on the video then it is in real life. I was actually shocked at how sensitive the microphone is on my s24.. it picked up the noise better then my own ears.

 

[CharlieS]

thankfully I only have a short puff when I open my gas cap.. which I'm pretty sure all our cars do.

No, they don't. Something is amiss.

 

[petegangies]

No, they don't. Something is amiss.

I'll record it next time I drive the car. I'll check our 2 other vehicles as well. You could be right. Three symptoms possibly related..

1. Charcoal canister buzzing
2. Few drops of fuel in FPR vacuum line
3. Short puff when opening gas cap to refuel

 

[BTLSHP]

I might simply start by pulling the tank line and seeing if the hiss happens there or goes away at the cap.....

 

[petegangies]

I might simply start by pulling the tank line and seeing if the hiss happens there or goes away at the cap.....

Ok. So after drive. Turn off vehicle.. pop bonnet.. unplug hose on tank nipple off cannister.. see if I hear the puff of air there.. if not.. go to gas cap and remove and see if I hear it there instead.