Not running and gauge is not moving on the dual tanks

[John Toohey]

Last night truck killed after stating it up and driving a quarter of a block. I noticed the the gauge isn't moving when I switch tanks or even truck is off. I disconnected the battery's to see if it would zero out and nothing. Truck fires but shuts off after a second. Would any one know what's going on. I'm gonna check the switch to see if that's the problem.

 

[Jason1377]

I'm a novice at these truck, but would start with the switch n go from there.

What year is truck sir n turbo or n/a would be helpful as well. You could also have a clogged line n could check ur fuel filter see if it's gummed,.also could try and use a fuel addative like seafoam n such see if that will help an try running from a fuel can, see if it is a pump or anything else.

Srry long post just ideas to try sir

 

[towcat]

the fsv and the gauges are fused. check your fuses first.

 

[Thewespaul]

If electrically it checks out, try blowing the lines out.

 

[John Toohey]

The truck is a 94 f250 7.3 idi stock turbo single cab. So far I checked the switch that was good I pulled fuses. Gage still didn't move. When i unpluged the tank switch valve mounted on the frame the Gage kind of moved back and forth from half tank to full and back to half. I know there's quarter in both tanks. I'm not hearing either pumps turn on so I'm wondering if a bad fsv interferes with the pump turning on and gauge readings. Idk I'm still looking for the ground for this system. I was gonna check for air leaks in the return lines and injector lines. I think blowing the lines out and checking in the filter for clogs first sounds more effective. By the way how do you blow the lines out where do you disconnect?

 

[John Toohey]

Just curious where do you guys go to check fuse diagrams? The diagram in my truck arent very helpful they just say fuse numbers and I haven't been able to find the fuel relay online.

 

[MTKirk]

Could be your fuel selector valve is stuck. I believe there is an internal part that slides back and forth to align the different ports, could be stuck halfway blocking return and/or supply. Try by passing valve, or replace?

 

[snicklas]

Also, there are no pumps to hear. Diesels do not have pumps in the tanks like the gas trucks do. You have a gauge sender / float and a fuel pickup in each tank, the FSV selects which tank it is drawing from. Unless it has been converted, the only pump is a mechanical lift pump on the passenger side of the block, similar to the ones on an older V-8. This pulls from the tank, through the valve, and then up to the fuel filter and IP.

If you have less than a quarter tank, and the fuel pickup is broken off (showerhead), then it will not pull fuel because the end of the pickup tube is not at approximately the 1/4 tank level, not the bottom.

 

[genscripter]

I know there's quarter in both tanks.

ooooh. That sounds a lot like the Cone of Failure....

Add more fuel regardless. At least a few gallons in both tanks.

From an article I once wrote on a similar issue:

1.) First off, put fuel in both your diesel tanks. Ford installed all fuel pickups to have these terrible plastic saucers in the tank that fall off. They are commonly referred to as the “cones of failure.” When these break, they don’t reach down into the last quarter of the tank, and even though your fuel gauge shows you have some fuel, anything under 1/4 is effectively “empty.” So put a few gallons of fuel in BOTH tanks, bringing up your fuel level to something the pickups can reach. Why both tanks? Sometimes your fuel selector valve may be stuck on one side, thus only pulling fuel from one tank. If you have one tank full and one tank empty, and the valve is stuck on the empty tank, the gauge will still read as if it is pulling from the full tank. By putting fuel in both, you can at least get your IDI running, and then you can troubleshoot the valve later. Also, some selector valves are water tight, but not always air tight; this means when there is an empty tank, it might suck a little air thru the empty side which creates some air infiltration and weaker running engine. By leaving a gallon of fuel in there, it always keeps the empty side a little lubricated and properly sealed up.
​

Even if it's not your fuel tanks, I'm leaning toward your selector valve is stuck. A bypass is a simple test, but first, put fuel in your tanks first to make sure.

 

[John Toohey]

Thats what I figured but wasn't sure if the lift pump needed a tank pump to supply it fuel thanks snickers.

 

[John Toohey]

Thanks for the advise genscripter that helps a lot I'll keep you guys posted

 

[chillman88]

When my selector valve failed, the truck would start, run for a couple seconds, then die. Just fyi. They can fail other ways, but that was what happened with mine. Still need to fix that on mine, I just bypassed it with rubber hose temporarily.