Bad rear tank- need help please!

[wmoguy]

I've not used my rear tank for a week or two as I thought I got some really watery fuel. After running on that tank for a minute or so under load I spew white smoke like you've never seen before....
Anyway, I drained the tank twice today by sucking it empty with an electric pump down the fuel filler line. Filled it with 10 gallons of fresh diesel, drove it, same problem..... So I repeated this process thinking I maybe still had some water in there. No dice, same thing....

I'm feeling like it's not a water in fuel issue. I'm wondering if I somehow have an air leak off the rear tank? My front tank gives me no issues whatsoever so it would seem that it's not the fuel selector valve leaking air.

Suggestions? It's driving me nuts only having 200 mile range right now.

 

[itsacrazyasian]

Your FSV may be a culprit. I've had them not switch fully so one tank will work and the other wont.

At this point i would drop the rear tank. Unless you know you sucked all the water out, its hard to empty a tank even with it completely out of the truck. I usually end up flipping them up so everything will drain out the filler hole.

You may be sucking air at the hanger or maybe at the quick connect at the sender? The sender might have rusted a bit and sucking air?

btw shove the big tank in there and you'll love it! I love mine!

 

[wmoguy]

One thing maybe slightly of value I forgot to add. After I flip back to the front tank it takes a good few miles of spitting and sputtering before things even back out. I suppose that could still mean water or air intrusion though?

 

[itsacrazyasian]

or it could be that your fsv never fully switched? Take all the lines off and blow some air through the two ports going to the motor and see if it switches properly. sample some of the fuel arriving at your fuel filter head off the rear tank. btw does it still have the stock shower or a piece of hose in it? I put a piece of hose on my old 91 and it clogged with a piece of the shower head and would surge.

Please do a fuel quality and quantity test.

 

[TWeatherford]

^^^ Yes. Air could be getting in somewhere between your rear tank pickup and including the FSV.

However, I've had a lot of air in my lines before, and never noticed much, if any, white smoke result. It just runs really rough like its not getting enough fuel (cause its not). You may indeed have water in there. If I ever have my tanks out I'll be welding a drain into them for this very problem.

 

[wmoguy]

Thx guys. I'm thinking it's still got the stock shower heads. I know I haven't messed with it. I'd guess the original owner hasn't either.

I was going to do my electric fuel pump swap this week. Guess I'll spend some more time underneath this thing blowing air in and out of it to see what's going on.

 

[itsacrazyasian]

pull the rear tank and inspect. it comes out very easily.

 

[wmoguy]

pull the rear tank and inspect. it comes out very easily.

wil do thx!

In the meantime All the fuel I pulled from the rear tank is in my centrifuge barrel now. Its pretty stinking hard to dispell the WMO cocktail from water so I filled a empty water bottle with the blend and will let it settle tonight and see what I've got going on there.

 

[Knuckledragger]

Could also be the showerhead has disintegrated. My rear tank ran funny for a while - then it quit altogether. Even full of fuel. Seems the little pieces of showerhead had plugged up the pickup tube. If left too long, it could make problems for the FSV as well. Drop the tank and look at the sending unit. If the showerhead is not on the end of the pick up tube, it is in pieces in the tank, lines and who knows where else.

 

[wmoguy]

Well I'm confident it's not a water issue like I originally thought. I ran that fuel I sucked out thru my water separators on my centrifuge rig and yielded no water. I even stuck a plastic water bottle of the fuel in our deep freeze several hours ago and no slushy.

It's gotta be the shower head or some blockage I think. Oh joy.....