I have an 86 F350, 460/C6 CC/DRW...
Truck runs fantastic with new Edlbrock carb. I have in-tank fuel pumps. I haven't had the truck very long, so I am still learning its personality.

Here's the problem(s).
1)With the switch on the front tank, it is still sucking off the rear...
2) Ran the rear tank out of fuel, It would not switch to the full front tank. I put 5 gallons in the rear tank from my gas can, started, ran fine for a minute.
I have a clear inline fuel filter at the engine so I can see what's going on...
When the key is in the "start" made (cranking the engine) the fuel filter fills up, then the engine starts. Then the filter empties and the engine dies. I finally got it started, and could see fuel pumping! I had to shut it off to move myh other car out of the way, and then started it again, and yes, a minute later it died.
I have power at the pump solenoid. That is the only electrical I have checked.

Luckily this happened very close to home.

What am I looking at? I will probably have the dealer work on it, as I think this may be a little over my head, but I want to know what I am in for, and don't want to get screwed by the dealer (although they have been very good in the past).

Help!

 

I need some feedback on this one..

 

The names escape me, but there is a solenoid operated valve, that is not working, which selects the tank and/or pump combination on a dual tank system. If this valve is 'leaky' you cannot get fuel to pull from one of the tanks. If it is totally inoperative, is will fail just the same, come to think of it.
The major cost will be labor in most cases. The valves are not made of unobtainium, just plastic/brass/aluminum/stuff. I would want to make sure that the dash switch is getting juice to the under vehicle solenoid valve before blindly replacing the valve.
Some of them fail in such a way that fuel is pumped from one tank to the other, rather than to the engine... Not too helpful... 'smatter of fact, people have had the fuel coming out the filler cap... or at least trying to escape that way.
tom

 

Thanks...that's kinda what I thought (or was hoping for). Is it strange that during the "start" mode the filter would fill with fuel, then empty when the engine is running?

 

Back pressure with no consumption... While in 'just about to start' mode, the fuel pump is energized for about 3 seconds to pressurize the system. It will pump fuel from wherever it can get it... but does NO volume to speak of, just pressure... No fuel is flowing anywhere unless there are problems with the injectors leaking down or the regulator leaking back or the fuel pump check valve failing... OR if you have a dual tank system, one of the crossover valves has a leak...WHICH is just what you expected to find.. Viola. Yeah, I know. So the pump can pressurize the system, but when it comes to doing any actual work of pumping fuel, no go. Too much crossover/leakback, or it does not get switched fully to the other tank, and is sucking air
You pick it.

I'm done
tom

 

FYI..for all interested parties. I know this may be a common problem so here are the findings.

The oil pressure switch went out, thus the shut down, and only pumping gas in start mode.

On top of that the soloniod had a bad connection...and a bad connection to the selector switch on the dash.

on top of that the tank selector valve was stuck, and is being replaced. Should be good as new. Pumps are OK.

I had the local Ford dealer (Sunset Ford in Westminster, CA) take care of this for me so I know it is done right. Total cost to fix all of this...$630. Sometimes it pays to pay a little more and have the dealer's guarantee on the work. These guys have made my truck like new again, and have done diognostics for me for free.

I'm happy with peace of mind.