97 F250 7.3 Fuel delivery air??

[slyhog022056]

I have a 97 ford 7.3 duL tanks problem. A couple of weeks ago my 97 appeared to run out of fuel. Since them I have added 7 gallons diesel into front tank. Fuel selector switch appears to be working. Filter cover off and cranking appears to be getting fuel / air but wont fill the filter housing. If I manually fill it it will sit and run until fuel gets about 1/2 way down in the filter housing, then dies. If I pressurize the front fuel tank I can fill the filter housing up. I think my in valley pump is not working and somehow draining back into the tank. I do not know if they are somehow tied inside the selector valve or filter housing or not. I have an electric fuel pump I can put inline after the selector valve but do not know which set of lines are for return and which are for delivery. I can not physically see the fittings on the selector valve, someone told my it is marked "delivery" on the side of it. I just need to know which line coming out of the selector valve is delivery. Is the return side hooked into the valley pump in any way so I can completely bypass it? Or do I need to leave that pump tied in?

 

[Rdnck84_03]

If you're questioning the pump being bad, check the fuel pressure at the filter housing.

James

 

[greenskeeper]

selector valve can fail to where it is sending fuel back to the opposite tank...is your rear tank slowly filling with fuel?

the fuel pump in the valley could also be bad, however they normally have a weep hole that leaks fuel when things get worn

 

[slyhog022056]

Well I have been smelling fuel for a few days before this happened but could not find a leak and my rear tank has had just 4 gallons in it for 5 years and is capped but the fuel gauge still reads about 1/8 tank. Do not know how I can check fuel pressure at the filter housing the nipple on the pump and filter housing are only 1 1/2" apart that hose is only 2" long and there isnt room there to get into it without removing 1 or the other. That fuel pump has only been in there for 6 years and in that 6 years it only has about 5000 miles on it.

 

[Rdnck84_03]

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In this photo you can see 2 Schrader valves, 1 with a black cap 1 without. That is where you check fuel pressure. I believe 1 is pre filter and the other is post filter. Not sure which is which though without tracing the lines.Someone can correct me if that is inaccurate.

James

 

[greenskeeper]

Well I have been smelling fuel for a few days before this happened but could not find a leak and my rear tank has had just 4 gallons in it for 5 years and is capped but the fuel gauge still reads about 1/8 tank. Do not know how I can check fuel pressure at the filter housing the nipple on the pump and filter housing are only 1 1/2" apart that hose is only 2" long and there isnt room there to get into it without removing 1 or the other. That fuel pump has only been in there for 6 years and in that 6 years it only has about 5000 miles on it.

schrader valve is easily accessible, idle fuel pressure should be around 65psi. Has the regulator ever been rebuilt? What about the screen.. has it been cleaned?

 

[slyhog022056]

Regulator has not been rebuilt to my knowledge, and which screen?? I have ordered a new pump and hoses since it has been suggested these tend to leak out the weep hole. the last one has only been on there a few years but I have been smelling fuel for a while now and the valley pan is covered in fuel. I get less than 2 lbs on either of the 2 schrader valves. Hopefully it is just the pump so I dont have to drop the front tank. I had bought a electric fuel pump, 5 to 9 psi and may just wire it into the glow plug relay and mount it after the tank selector valve. If I can figure out which line is feed and which one is return.

 

[Rdnck84_03]

If the electric pump you have only pushes 5-9 psi it will not work. The ford spec I believe is about 60 psi.

James

 

[slyhog022056]

I only want it to run while glow plug relay is energized to feed the manual pump and fuel into the filter housing.

 

[Rdnck84_03]

Other than adding unnecessary crap it will not do anything.

Unless something is leaking they will never loose its prime. If that is the case just fix it correctly, the only way to reprime it with a secondary pump is if it makes enough pressure to overcome the pressure regulator which is somewhere around 60 psi.

James

 

[greenskeeper]

Regulator has not been rebuilt to my knowledge, and which screen?? I have ordered a new pump and hoses since it has been suggested these tend to leak out the weep hole. the last one has only been on there a few years but I have been smelling fuel for a while now and the valley pan is covered in fuel. I get less than 2 lbs on either of the 2 schrader valves. Hopefully it is just the pump so I dont have to drop the front tank. I had bought a electric fuel pump, 5 to 9 psi and may just wire it into the glow plug relay and mount it after the tank selector valve. If I can figure out which line is feed and which one is return.

A faulty regulator won't build the proper psi as it would just dump fuel back to the tank, and a clogged screen will restrict flow. Both are located on the side of the fuel bowl.

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[94NAIDI]

It’s super easy to replace the mechanical lift pump In the valley. While in there, pull the filter housing to help ease with the pump replacement and rebuild the regulator and clean the screen. The regulator rebuild is just a matter of replacing some o-rings and cleaning out any gunk. There are very good videos on YouTube showing step
By step How to do it. My 97 Powerstroke was doing the same as yours. I ran out of fuel on a drive and was stranded. Pump replacement and fuel bowl/regulator rebuild and it’s like a new truck again. My screen was completely clogged with crap.

 

[94NAIDI]

Also, leaking fuel in the valley and low pressure could be the rubber hoses that run between the pump and the filter housing. So while your in there replacing the pump and rebuilding the regulator. Replace the short hoses that go between the two.