Just bought a 1997 F250HD 4x4 with a 5.8/automatic it's has 98450 mIles on it. When I test drove it for 15 minutes it ran great, when the previous owner drove it to my place(I followed him in my truck) it drove just fine no problems ect. I take it out today for it's first day of work and all was going fine, then while on the highway it started to lose power and would just creep along sputtering till it finally just stopped. Waited awhile and it started up and drove fine for a mile or so then did the same thing....sputtered and lost power then stalled. The truck was used by the previous owner to just plow his driveway he owned it for 2 1/2 years and put a whole 1100 miles on it, the owner before him used it for the same reason....mostly just plowing his 1200' drive so the truck has never been used commercially. I'm not sure where to start looking for the problem. Since the truck has basically just sat for the last 2-3yrs, what do you guys think I should be looking at first?.....fuel pump/sending unit.....injectors...fuel filter or ?????.

 

The fuel filter would be a good place to start since it sat around most of the time.

 

I checked the fuel filter and it seems to be fine, I blew through it and didn't get any resistance. I noticed that the fuel line had a 2' section with four 2"-4" pieces of hose spliced together with metal line and a million clamps, so I took them out and install one piece of fuel injector gas hose. The previous owner said that once the gas gauge gets between the 1/4 full and the half full mark the truck runs out of gas even though the gas tank is still nearly half full. He thought that perhaps it has the wrong pump in it and just wasn't reaching deep enough into the tank. We checked the unit and it does go to the bottom of the tank and it seems to be alright....is there anything I should be looking for on the pump/sending unit that might be causing it to malfunction once the gas tank gets to a certain level?

 

You're not going to like this, but you may need to drop the tank and check the connections for where the pump draws fuel. It is supposed to draw from the bottom at the sock filter, but there might be a problem allowing air to get drawn in from a point higher than the sock filter. There have been occaisions where there was a leak in the delivery line to the engine within the fuel pump module.That location could be at the 1/4-1/2 full point. If you can't find anything you may have to replace the fuel pump module itself.

 

LOL....actually checking the fuel pump is the easy part Hanky, the truck had a dump hoist install under the bed,so all I have to do is hit the switch and I got access to everything under the bed. We did pull the pump to check it, thinking that it might have been the wrong pump and just wasn't drawing from the bottom of the tank but that wasn't the problem and everything looked ok with the current pump, but I'll recheck everything just to make sure. There is a slight crimp in the rubber filler hose, could that be causing some sort of vapor problem in the tank? Since it's easy to get access to the tank area I went out and took a pic of the hose. The pump is suppost to be fairly new..installed by the first owner just before selling it to the previous owner, but again it's been sitting around most of the time since the previous owner bought it. When it "runs out of gas".....it sputters to a stop and feels like it has vapor lock, but it has EFI. Oh by the way that leaking brake line I had on the cargo van finally got fixed....took off the copper/nickel replacement line and went with a plain steel line and the leak stopped.....go figure!!lol i don't see how to post pics on here using my iPhone so I guess I won't be able to show the filler hose, but I'd guess the crimp is cutting the id of the hose by 50% where it's bending/crimped.

 

If the pump output is losing pressure possibly from the internal hose connections you will not see that just looking at the pump module. You would need to operate the pump and observe for any possible pressure loss in the module area. Some of these problems cannot be spotted unless the system is in operation.

They do have epoxy coated brake lines that are available to prevent a recurrence of rusting. I have used them and they do solve the corrosion problem. Just a little FYI for future use if desired.

 

Once I get the pump out how do I test it? I've just been keeping the tank filled and it runs like a champ as long as I don't let it dip much below half a tank. But I hate driving something that I know has a problem, even though keeping the tank filled works.....it still drives me nuts knowing there's still an unsolved issue.I also changed the gas cap since the one on there turned hard and didn't make that free turning clicking sound when it was tight.....don't know if that'll help my orginal problem but it can't hurt.lol

 

What do you think of this?
Set the pump module in a 5 gallon bucket with gasoline and all the wires connected and just cycle the key on and off allow the output line go into another pail to collect the gas.
When the level in the supply bucket gets down to the trouble spot you may be able to see where the pressure is going. You do need to be careful because everything is out of the tank and gas could get splashed.This might be a good thing to do outside of any building.