[BlueDiamond]

I'm sure this has been discussed in here but I have a 1997 F250 7.3 and I am having an issue with the truck idling rough and then it runs out of fuel. When I open the fuel bowel, there is no fuel. I know the 2000 model has two screens in the sending unit that usually get dirty and then they have poor performace. Does my 97 have the same sending unit with the screens? I am assuming this is why my truck idles rough and then cuts out. No fuel due to dirty screens.... Can some one verify my suspicion or am I wrong?

Don't want to drop the tank if I don't have those screens. Also, I have a full take of diesel!

 

[madpogue]

Yeah, we have the same screens ("showerheads") on the pickup tubes (the sending unit is for the gauge), or similar ones anyway. What usually happens is that the screen breaks or falls off, so the pickup tube only reaches down to about the 1/4 tank level. So the truck runs out of fuel at 1/4 tank. Is this happening on both tanks?

The other possibility is that a piece of the broken strainer has been pulled up through the pickup tube, and has lodged in the selector valve.

 

[action4478]

I'm sure this has been discussed in here but I have a 1997 F250 7.3 and I am having an issue with the truck idling rough and then it runs out of fuel. When I open the fuel bowel, there is no fuel. I know the 2000 model has two screens in the sending unit that usually get dirty and then they have poor performace. Does my 97 have the same sending unit with the screens? I am assuming this is why my truck idles rough and then cuts out. No fuel due to dirty screens.... Can some one verify my suspicion or am I wrong?

Don't want to drop the tank if I don't have those screens. Also, I have a full take of diesel!

Do both tanks act the same ? If so you may need a pump . You may need to look for leaks on the draw side too .

 

[BlueDiamond]

Thanks for the reply's. I just changed the fuel pump under the turbo thinking it was that...still dies. I haven't tried the other tank as I don't use it because the sending unit is bad and I don't know how much fuel is in it. I guess when I drop the tank I'll see if the screens are bad. Thanks for the input.

 

[BlueDiamond]

Well, I dropped the tank and pulled out the sending unit. These trucks DO NOT have the same screens like the 1999-2002 models. I have included pictures of the sending unit. It just has the one pick up screen that falls off like every ford sending unit.

My tank does have some trash in it, so I hoping that it's sucking up trash which is making my truck run out of diesel. Ill keep you posted just in case anyone else needs the info.

 

[Steve83]

Pic doesn't work for me. :icon_rolleyes:

 

[madpogue]

Did the strainer indeed fall off? If so, and it sucked anything up, as mentioned it's probably lodged in the selector valve.

 

[BlueDiamond]

Today I put on the new strainer that I got off amazon for $30. Cleaned out the tank the best I could. Installed the sending unit, Installed the tank and then filled the fuel bowel with diesel. Filled tank with diesel, about 1/2 tank.

Truck started up, got rid of the air and the truck idled smooth. I let it run for about 30 min and it ran great. Took it on a test drive around the block......began running rough again. I was able to get it to the shop and turned it off. Looked in the fuel bowel and it was empty!!! WTH?? WHY is the fuel bowl not filling up?? This is driving me nuts?

Being that this is a mechanical fuel pump and the plunger rides on the cam, is it plausible that my cam lob is flat and no longer pumping like it should? Anyone have an issue like this?

 

[Dallas97PSD]

I am interested to find out if you solved the problem because I also have a 97 F250 and also live here in DFW.
The theory of the cam lobe going flat is very unlikely. It's a steel billet cam pushing a tiny flat piece that needs a lot less effort to push up than the lifters. Those lobes would go flat much faster than this one would.
I also don't think that you have a vacuum problem in the tank because if you poured half a tank of diesel and you only ran it for about 30 minutes and then the engine stopped, I don't think it would've built enough vacuum in the tank in 30 minutes to counter the suction of the pump.
Since you have already tried two different pumps and it is still doing the same thing, it is so obviously not the pump, so by elimination I think you have a restriction in the fuel line between the pump and the tanks that causes not enough fuel to flow at low RPM, and the engine burns it up faster than it flows, so the fuel bowl gradually empties. And only above a certain RPM, more fuel will flow than the engine needs to burn.
You could check this by installing a fuel pressure gauge in place of the Schrader valve at the fuel pressure regulator and seeing if the fuel pump holds pressure at, let's say, 2000 RPM and then let it idle and see if the pressure slowly decreases down to almost 0. If that is the case, blow shop air from the inlet of the fuel pump back thru the line by disconnecting the other end from the tank, and try to catch whatever comes out with a shop rag so that you know when you got it.
That's my two cents, or five. That's what I would do.

 

[madpogue]

^^^^^ Most likely fuel line restriction would be foreign matter pulled up from the tank, lodged in the selector valve. If I were to use compressed air to blow the lines, that's where I'd start.

But trying two pumps does NOT eliminate the pump. Only if either/both pumps had been proven working in another truck would that be true. Another way to narrow it down would be to disconnect the inlet to the first stage of the fuel pump, and feed the truck from a jerry-can of fuel, see if it stays running that way.