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Discussion Starter #1
Hi,
I have a QP 2005 Duoselect. Since few months ago I'm experiencing a strange noise coming from my gas tank. It only happens when the gas tank is half empty.
The noise is like a "clonk". For me its like some kind of air or gas pressure related problem. It is not related with the speed or gear, even if the engine is on but the car is not moving will make the noise .
Its a random noise every 2 minutes or so. Very annoying. The less gas I have.. the stronger and more repeated the noise is.
Did anyone experience this issue before? Any help will be appreciated.
Thanks
Sergio
 

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what happens if u loosen the gas cap to relieve pressure. try it and see what happens. if it stops then it could be the pressure relief valve
 

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Discussion Starter #3
If i loosen the gas cap i don't feel any air going out. However, today i realized that In one gas station.. when i inserter the gas nozzle it was not able to flow the gas but itself (sorry, my English is not so good.. so i try to explain using simple words)). What i mean is: you insert the nozzle and fix the trigger which will automatically stop once the gas tank is full. However, i was not able to fix it. After one second, the trigger was released.. one time, two times.. and then, after 1 minute, I was able to fix it.
Any idea?
thanks!
 

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If i loosen the gas cap i don't feel any air going out. However, today i realized that In one gas station.. when i inserter the gas nozzle it was not able to flow the gas but itself (sorry, my English is not so good.. so i try to explain using simple words)). What i mean is: you insert the nozzle and fix the trigger which will automatically stop once the gas tank is full. However, i was not able to fix it. After one second, the trigger was released.. one time, two times.. and then, after 1 minute, I was able to fix it.
Any idea?
thanks!
I cannot answer your question for you but do not worry about your English.....it is very good.:thumbsup:

Better than our Italian or Spanish :thumbsdown:

My guess is that something has fallen in to your gas tank and is floating loose in there.... just a guess
 

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If i loosen the gas cap i don't feel any air going out. However, today i realized that In one gas station.. when i inserter the gas nozzle it was not able to flow the gas but itself (sorry, my English is not so good.. so i try to explain using simple words)). What i mean is: you insert the nozzle and fix the trigger which will automatically stop once the gas tank is full. However, i was not able to fix it. After one second, the trigger was released.. one time, two times.. and then, after 1 minute, I was able to fix it.
Any idea?
thanks!
I find that sometimes my QP will not take fuel with the trigger set. I think it has more to do with the flow rate of the pump than anything else.

Did you try leaving the gas cap off with the car setting and engine off?
 

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Discussion Starter #6
Im almost sure is something related with the gas/pressure. I'll drive my car to the garage to check whats going on becuase the noise is really annoying.

Should I try to drive the car without the gas cap? Does it sound too crazy? Will this stop the gas pump from pumping the gas becuase there will be no air pressure inside the gas tank?

thanks!
 

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If you drive without the gas cap, you will initiate a check engine light. And that will be even more annoying. I am with William on this, something somewhere inside your gas line has fallen into the gas tank and is sloshing around when the gas is only half full and making all sorts of clunking noise. I used to install one of those fuel saver "bullets" (look like a bunch of marbles) that are supposed to be tied to the inside of the gas tank and one day all I could hear was, well really, a bunch of marbles clinkering around and it was really annoying. I had to rip out the whole gas tank and find the fuelsaver bullet one by one and clean them out. This was in my Toyota Aristo. Needless to say, I will never try this again on my other cars....
 

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IF u read Esergio,s opening statement he claims it makes the noise while the car is not moving. IM heading in the direction of the relief valve. ESERGIO,
 

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Discussion Starter #9
hi all,
the noise is at anytime: no matter if idrive the car or not.
I can be very sure that the noise doesnt come from anything physically inside the gas tank, but its something related with air or gas pressure.
It only happends when the fuel tank is half full. right now, to avoid it.. what I do is full till the tank when its half full. Taht works.. but means i need to stop every 250km or so
 

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Sergio, the most likely cause is the tank vent that is connected to a charcoal cannister to capture all the gasoline fumes. If the vent hose becomes clogged, pinched or if the charcoal cannister is clogged, it will not allow fuel to be entered into the tank. The tank has to have a method of releasing air while filling, if there was no tank vent you would never have a full tank of fuel. The noise you are hearing is most likely the tank "oil canning", the tank is actually expanding and contracting depending on the pressure in the tank. I have presonally been involved in these repairs numerous times in the last 40+ years. Believe it or not the most common cause on modern cars are spider nests built up on the vent outlet of the charcoal cannister. Why they like fuel fumes is beyond me but they do, and the nests sometimes are so well built you can't even blow them out with air pressure. Sergio have someone look at the tank vent. Hope that helps.
 

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Discussion Starter #12
8339: thanks for ur detailed reply. I was told something like that before. Do u have any idea where is that vent hose as lorenz-gs06 said? I'll drive my car to my local garage and they are not familiar with QP. The QP dealer shop is 400km far from me.
Btw, is it possible to damage the gas tank because those contractions? Someone told me that his tank was damaged with a small hole because of this.
thanks in advance
 

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You need to pull the forward panel in the trunk, the fuel tank sits behind it. The vent hoses should be on the passenger side or opposite for the filler neck on the top of tank. The charcoal cannister I believe sits in front of the tank. The may be more than one item not correct with the system. If you can reach the vent hose you need to see if any of the hoses are pinched or collapsed. If you can dis-connect the main vent hose (there are few hoses and a distribution box) with the fuel cap off and by using a secondary hose attached to the main vent hose, blow into it and see if it's clogged. Be careful not to draw in any fuel in your mouth, also be careful as fuel may spill out of another hose, or one of the vent hoses could become dis-lodged and push fuel. No open flames or overly hot drop lights, and have lots of rags just in case. The best thing is to take the car to qualified Technician, if you were in my area you would be bringing it to me.
 

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You need to pull the forward panel in the trunk, the fuel tank sits behind it. The vent hoses should be on the passenger side or opposite for the filler neck on the top of tank. The charcoal cannister I believe sits in front of the tank. The may be more than one item not correct with the system. If you can reach the vent hose you need to see if any of the hoses are pinched or collapsed. If you can dis-connect the main vent hose (there are few hoses and a distribution box) with the fuel cap off and by using a secondary hose attached to the main vent hose, blow into it and see if it's clogged. Be careful not to draw in any fuel in your mouth, also be careful as fuel may spill out of another hose, or one of the vent hoses could become dis-lodged and push fuel. No open flames or overly hot drop lights, and have lots of rags just in case. The best thing is to take the car to qualified Technician, if you were in my area you would be bringing it to me.
8339 - where is your area?
 

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Discussion Starter #15
8339: thanks a lot for your reply, really appreciated !
I live in Spain :( so i don't have the chance to drive my car to your place :(

Tomorrow I'll drive my car to my local garage and I'll print and translate your detailed instructions.
Btw: Is it needed to remove the gas tank from the trunk? Or can all that test be carried with the gas tank in its original position?

THANKS so much
Sergio
 

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Sergio, I hope that works for you. Veloce 49, I own Radcliffe Motorcar Company, north of Baltimore. Thanks
 

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Sergio, I hope that works for you. Veloce 49, I own Radcliffe Motorcar Company, north of Baltimore. Thanks
8339 - That's good to know. I mentioned your shop in another thread when someone was looking for a Baltimore shop. I'm a Baltimorean by birth and Ravens season ticket holder.
 

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8339 - That's good to know. I mentioned your shop in another thread when someone was looking for a Baltimore shop. I'm a Baltimorean by birth and Ravens season ticket holder.
Ron - what are the chances the Ravens & Steelers will have a re-match in a few weeks? F1 relay is sitting on my counter......
 

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Ron - what are the chances the Ravens & Steelers will have a re-match in a few weeks? F1 relay is sitting on my counter......
Phil - I hope we get a re-match. It's really becoming one of the great NFL rivalries.
I'm kinda glad we are not starting with the Colts who really seem to have our number.
Good luck. The F1 relay would certainly be on the line.
Having lived in Pittsburgh for a couple of years, I am not a Steelers hater like most Ravens fans.
 

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Discussion Starter #20
8339: i followed ur instructions and blowed the hose.. at the other side lots of brown (?) dust came out.. now I blow and i just get "clean" air. I'm going to drive my car for a while to see what happens.
I phoned the Maserati dealer in Spain, they told me that the "black box" (i dont know the english name, in spanish its 'canister') need to be replaced after some time. But they are not sure yet if the noise comes from there or not.
I'll keep updated. Anyway.. i really appreciate your help.
Sergio
 
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