Fuel starvation with dual tanks

[EricN]

Ok, I have an auto with the dual tanks. Someone mentioned how both tanks suck fuel at the same time. I dont understand how this would work properly with 2 different volumes in the tanks but whatever.
My problem is that when I am getting lower in fuel (1/4 tank) and I stop on a steep hill or do an agressive turn and come to a stop, I suck air (I think, sure feels like air) and the idle stumbles and eventually dies if I dont keep the rpm up. I tried it on a steep driveway today. Works fine, get to the top of the driveway, let it idle for about 10 seconds and it starts to stumble, eventually it will die. If I quickly roll back to flat, it recovers after about a minute and is fine. Does anyone else have this issue??? It is a real pain and I am going to put a transfer tube with a one way valve at the bottom of the 2 tanks if this keeps happening but I am running out of time to work on it before back surgery and I still have to pull the rear diff apart and check for a problem in there (I think I have a broken pin or something, not sure yet).

[BCDelica]

So you haven't been under the knife yet?

I will only guess here, but the pick up in the tank is this little cup, screenie thing that can get a flim on the bottom blocking flow. Our first Deli had just over 40000 k before dropping the tanks, the screen had some sort of film over the bottom that would have blocked flow - this was in a tank that hadn't seen veggie. Struck me as a good reason to use biocide, and that little 30 buck bottle will last forever. Not that I have tell you.

[EricN]

So you haven't been under the knife yet?

I go in on Monday, doesn't feel like enough time to sort everything out.

Not that I have tell you.

I am comfortable with attempting to tear apart and fix everything on the truck, I would even do the injection pump, and could diagnose anything, but I have ZERO knowledge on how EXACTLY a diesel works. I understand the basic concept and can stumble my way through it but any driveablity issues are going to be a complete guess. Experience is knowledge, and I would entertain anyones opinions.

As for fixing it, I went and bought some biocide and will just keep the tank full (no problems with a full tank) and hope it fixes itself or doesnt get any worse before I am able to work on it again.

[Green1]

I'll admit I'm speculating here, but how does the fuel pickup in these tanks work? some vehicles have a tube entering the tank at the top and then reaching to the bottom of the tank to suck up fuel, if that tube is broken, or has a hole in it higher up (but still inside the tank), then you'd have to keep the fuel above that level to avoid the problems you describe.
You also say it's ok on a full tank... just to be clear, how many litres down before you have a problem? (if it's 60+ then you should be aware that the tanks are only 70 litres and if the fuel guage doesn't show empty at that point the culprit may be the guage or sensor rather than somthing else)

[EricN]

The fuel tanks have a really strange (as far as I am concerned) setup. Apparently they only transfer fuel at the top, and they both suck fuel at the same time when running. TO me it seems possible to have 1 tank suck itself empty and the other one still have lots of fuel in it (ie: plugged pickup screen in 1 tank). Since the fuel sending units are connected in series, this would also show as having lots of fuel in the tanks.
I filled it up and it took 40 litres and showed 1/4 tank before I filled. I know my low fuel warning light does work since it was on when I first got the truck and the truck still ran fine. Again though, if there is 2 sending units then I suspect there are 2 liquid sensors and if they are in parallel, it should trigger the light if 1 tank is empty, unless it just so happens that fluid sensor is dead in that tank.
I guess the hole in the pick up tube is a possibility too, just seems unlikely. Next time it happens I am going to drain each tank and see how much fuel comes out of each individual unit.
For now, the rear diff is my biggest concern. The more I think about it, the more convinced I am that I have a broken pinion cross shaft. Maybe that will be tomorrows project.

[Schwa]

I went and bought some biocide

Where did you get it?

[EricN]

http://superpages.ca/bus/British-Columb ... 5.html#Map
poco marine, just past the westcoast express station in poco there is a little strip mall. Enter the driveway and do an imediate right, he is on the side of the building facing away from the train station. I bought a big fancy bottle with a little measuring cup built in for $20 but he also had some smaller ones for around $6 (I think).

[Schwa]

thanks, I'll stop by and grab some

[DelicaMark]

I saw yesterday that Lordco (in Duncan) carries some Biocide. The Raycor brand. I will note that it was cheaper buying it from Noel at EnviroImports than it is from Lordco....and Noel delivers!