Fuel tanks not equalizing and left tank empties faster than right one

Got a 99 Pete 379 that won't equalize between the tanks, nor will it pull evenly either. Driver side tank empties faster than the passenger side one to the extent of when it comes time to refuel, left tank will be around a quarter and right tank will be between half and 5/8ths, ish. I can get it to pull a little more evenly if I pinch off the right side tank's return line a little but, it still pulls faster from the driver side tank. As far as I know both tank vents are clean and clear from debris but, they aren't the same tank vents. In other words, the passenger side tank is from some other truck because it's a combination fuel/hydraulic oil tank.

Any suggestions?

 

I don't think this truck has a typical crossover line or atleast not the kind I'm familiar with. Both supply and return lines from each tank go straight up to the frame rails on each side and run up underneath the cab of the truck.

I'm guess I could have something in the right tank obstructing th flow before it goes through the valve.

I guess the valves could have different inside diameters. Never thought of that. Ad I said, that right combo tank ain't even the original tank that was on this truck.

Haven't checked them in a while but, I have checked them numerous times before as this has been an ongoing issue ever since I've been in it.

I'll pass along some of this info to the mechanic and maybe he can figger it out. Thanks.

 

Could very well be. These fuel lines are ancient looking....lol.

 

Hmmmm...lol.

When I get fuel today I'll recheck the vents.

 

Just got fuel a little while ago and both vents were clean and clear. Also, left tank was about quarter and right tank was a little above quarter. Pinched off the return line a little further on the right tank when I filled up and now up here at my drop, pulled the caps off and seen that the right tank was a little lower than the left tank. Maybe I got it somewhat figured out now...lol.

Hate to run it like that but, whatever works, right?

 

You're right, maybe when they decide to replace my fuel lines, that'll fix the problem but I'm afraid that since I got two completely different tanks on here with different parts, this may continue to be an an ongoing problem.