2003 Bi-Fuel Cavalier makes funny noise

[kmcqueen]

Preface: I'm new to CNG.

I just took delivery of a 2003 Chevy Cavalier. I had an additional tank added in the trunk by cngmotors.com

It looks like this: http://www.cngmotors.com//gal/cng/po...os/cavtank.jpg

My question is this. As I'm driving, there is a funny intermittent (a few to several seconds apart) noise that comes from the rear of the vehicle. It sounds like a medium pitch tone (the pitch varies from time to time a little). The timing of the tone seems to vary with how much fuel I'm pulling from the tank (infrequent if idling, more frequently if accelerating). It is louder sometimes than it is at other times.

Is this sound normal? I'm worried that the high (low?) pressure regulator is failing.

Does anyone else have any experience with this?

Keith

[Techie]

Re: 2003 Bi-Fuel Cavalier makes funny noise

Preface: I'm new to CNG.

I just took delivery of a 2003 Chevy Cavalier. I had an additional tank added in the trunk by cngmotors.com

It looks like this: http://www.cngmotors.com//gal/cng/po...os/cavtank.jpg

My question is this. As I'm driving, there is a funny intermittent (a few to several seconds apart) noise that comes from the rear of the vehicle. It sounds like a medium pitch tone (the pitch varies from time to time a little). The timing of the tone seems to vary with how much fuel I'm pulling from the tank (infrequent if idling, more frequently if accelerating). It is louder sometimes than it is at other times.

Is this sound normal? I'm worried that the high (low?) pressure regulator is failing.

Does anyone else have any experience with this?

Keith

I would recommend you have someone drive the car. Yourself, go in the back seat, fold down the seatback and listen where the noise is coming from.

It is not too unusual to hear small levels of noise as gas is flowing from one cylinder to another as they are linked. The gas is being moved from front cylinder to the regulator. As front cylinder pressure drops, rear cylinder makes up for it so you may hear a hissing sound.

You can also turn off the rear cylinder and if the noise goes away, then, what I have described earlier is the condition and it does not require repairs.