[urq] What causes knock ?

[Brandon Rogers]

I've had my fuel tank make the bong sound too - first time scared the 
beejesus outta me....

Brandon

----- Original Message ----- 
From: "Louis-Alain Richard" <laraa at sympatico.ca>
To: "'Urq List'" <urq at audifans.com>
Sent: Thursday, May 11, 2006 7:13 PM
Subject: [urq] What causes knock ?


> My car developed some strange sounds, and one is sounding a lot like
> knock. It happens only under boost, and it is sporadic. But it scares
> me, specially after what happened to Dennis...
>
> The second strange sound is identified, it is the fuel tank collapsing
> after a few minutes on the highway, a big "bong" sound. Today, as the
> fuel tank was nearly empty, I stopped and noticed that the fuel cap made
> the "iiisssssss" sound of air entering the fuel tank. So there are no
> fuel vapors going back to the tank, IMO.
>
> Now, are these 2 problems related ? Can a fuel tank that is under vacuum
> stops the fuel flow to the pump and starve the engine ?
>
> Then, how can I find the problem with the fuel vapor circuitry ?
>
> And my title question remains: what causes knock ?
>
> Louis-Alain
>
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