My idling, '96 CTD warmed up truck seemed to be emitting a tone of some sort from the general vicinity of the fuel tank when I got home today. My hearing is bad so I can't be sure. Is there a fuel pump of some sort in the fuel tank? Any other ideas?

 

No pump in the tank. Sometimes the return fuel line will make a slight buzzing sound. You usually can't hear it over the sound of the engine though.

 

You could be getting some holes in your exhaust. My tailpipe from the muffler back was all rusted out on top from all of the salt that is used on the roads. Just a suggestion.
dave

 

In my 99 the air vent tube to the fuel tank seems to get clogged up every few months and whistles even after I shut the truck down, as it draws air pressure in. When I hear this I know it's time to shimmy under there and stick a nail through the hole to clean it out. It's located on the top of the fuel take right next to the hoses.

 

My truck makes a ticking sound coming from that area, not sure what it is. Mabye the Catelytic Converter? It is not very loud, but still bothers me.

 

A steady tick from the return line with the lift pump pulsing is normal.

 

Normal for a cat to tick while it's cooling down. Easy to fix though...

 

Did a search and found this thread. No point in starting a new one.

I've noticed a puffing sound coming from under the truck. It is quite noticeable when walking around the bed area of the truck with the engine idling. Not a steady "puuuufffff", but a "puff, puff, puff, puff". It's the same tempo as the idle of the engine, although, I haven't determined whether or not the puffing speeds up as the engine speed increases. While at the exhaust shop yesterday, I spent some time under the truck with the engine running, and isolated it to the fuel tank. So, the general consensus is that this is a normal sound? It's not caused by a faulty valve anywhere?