Peterbilt 379 fuel tanks not staying level

If you've replaced everything first make sure all your return hoses are the same length and routed so they are all at the same height. And difference if restriction will cause it to return to one side. If everything is right I'd just put #### off valves on the returns and whichever one is returning more just close the valve down half way or so. Play with it till you get them returning even

 

I drove a 1999 379 that did that too. Sucked fuel out of drivers side to passenger side, to the point of causing it to overflow…got stopped by a local cop due to the leaking fuel. I was worried about a hazmat situation.

 

Should be the same as a KW. Draw and return from both sides go through the same valve. They screw up now and again and return more fuel to one side.

 

I probably should have added I’ve had problems with new ones. I’ve learned that just because I put a new one on doesn’t mean it’s not ####ed up too. Changed 3 on one truck before I got one that worked right.

 

The valve that the draw and return go through. I’ve had a few new ones now that were bad out right out of the box. One was fubared totally. Changed it, and I started the truck the next morning and went for breakfast. When I got back one tank still had snow on it and the other was bare and dry. Brand new valve and it only drew and returned to one side. The others just didn’t draw and return equally like they’re supposed to.

 

2022 389 got the same issues as I had in older 379’s. I think they just are not right and Paccar engineering don’t care. Add more useless crap but don’t improve on basics…