Equal length fuel lines important?

I don't want to over think anything without being there looking at your specific tank. Fuel goes to the engine and sometimes there is a return of some to keep it heated. And there is usually a line to balance both tanks with one being a primary drinker of fuel to the engine. So sometimes when you are sloped away from the drinking tank and it drains out into the other one you aint starting.

Usually there are valves on the tank or tanks to enable isolating for mechanic purposes. We tried after one episode where one side was never "Turned on" for a week to make sure that it draws from that one or both always.

 

If your setting up dual draw and dual return and plan to have no bottom crossover. Yes, you will need to put in a center tee for both suction and return lines. Making the lines as close to the same length as possible and ensuring that they are routed at the same height with the same gradual turns will be important to tank level side to side.

Paccar dealers I know should stock a gated return tee which helps keep the return flow rates the same and the tanks level. Most dealers should stock them as well as the open tees which are mountable.

 

I believe it was around 1995-2000 that trucks went away from the bottom cross over line from between tanks. I wouldn’t be surprised if that was a “government suggestion”.

So depending on the year of your truck. You may need to install it with the dual line set up.

 

While on this topic if you dont have a bottom cross over tube do you have to fill both tanks or will the truck still level out your fuel level

 

It will level out, even while not running. It takes time though. But, if you only fill one side by the time it levels you'll only have 1/2 tanks or slightly over.

 

I'm asking because I have a truck that I filled the driver's side tank up and left the other with less than a quarter tank and drove another hour went to get off the interstate to get a cup of coffee and the truck ran out of fuel when it got under 1,000 rpms the passenger side was sucked dry and the driver side was about the right amount of fuel burn but when filling both tanks they empty at the same rate

 

Check your tanks vents. Some have vented caps, rollover valve, or just elbow Barb fitting.

 

A quick check for blocked vents is to just leave the fill caps loose. If everything levels out you definitely have a blocked vent. Otherwise, you have a restriction somewhere between the tanks and the tee's.

 

no they won't, the tube is there just for that purpose and without it, there is no way fuel can move on its own from one tank to another.