My 93 F-250 7.3L IDI is having problems with the front tank. I was driving down the highway and my fuel filter light came on so i got off the highway and it went off after i dropped bellow 1500 RPM's. Then i got back on and as soon as I hit 65mph about 2000RPM's the light came back on and she started chugging and then back to normal with the light still on till I got off the highway. Replaced the filter and its still doing it.

I had put a full tank of Off Road diesel into the tank and was still runnin on it when this happened. Regular in the back tank and it didnt have that problem.

But if its not fuel could it be something else?

Truck does have IDI pump tuned up 3 flats. Never had this problem for a year after pump was tuned up.

 

might be a problem with the fuel pickup tube and its just showing the beginnings, when under heavy throttle it might be pulling in some air. Also could be the lift pump failing to push the right pressure. Or it could just be crap fuel.

 

Sometimes off road diesel could be no2 furnace oil. Our fuel guy mixed that up once and everything ran like crap and smoked bad. Its supposed to be the same stuff but it just seemed the furnace oil was dirty. And also check and see if your tank is venting properly

 

how can i check to see if the tank is venting right

 

The easiest way is to run the truck untill the fuel filter light comes on, then remove the cap from the tank you are pulling from. If you hear air sucking into the tank when the cap is removed the vent is plugged.

 

well the light only comes on when im doing over 65 mph and goes off when i get the truck to idle

 

yea No. 2 diesel and No. 1 fuel oil are not at all the same thing..lol did it quit doing it after you ran the on road fuel through it?

 

run it with the cap off.

 

Normally the filter light illuminates when there is a vacuum in the filter header. Mostly caused by a plugged filter or bad fuel lift pump.

Do a pressure and flow test of the fuel pump at the Schrader valve on the filter header (FSS- fuel shutoff solenoid disconnected on IP). Remove the tire valve core and hook a hose and pressure guage on it should see 4-6 psi when starter cranking engine over. Then do a fuel quantity test same place, should see 1/3 pint in 10 seconds of starter engine cranking, route fuel to a suitable container with a hose. When all finished hook up the FSS wire .

If there is a problem with the lift pump and you are changing it, ensure the new pump comes with instructions as to correct installation procedure if it is the newer model pump with the almost straight arm.

As for the tank the only vent is in the cap........ pressure and vacuum
Fuel cap Vacuum and Pressure

Vacuum ..... 0.05 psi
Pressure......1.6 psi

 

Well if your talkin about the fuel filter with having a vacuum then why would it be when as soon as i switch tanks the problem is gone? I've been told by Ford to drop the tank and see if the pick up tube has any holes in it or if the sender has been damaged. Where is the lift pump located anyway?

 

For the lift pump start at the fuel filter and follow the line down the side of the block. It bolts to the right side of the timing cover. And with the fuel light as soon as you switched tanks you are on a well vented tank and the lift pump doesnt pull a vac. And you are using more fuel at 65 then at idle and its possible the tank vent cant keep up. swap fuel caps between the tanks and see if the problem follows the cap

 

ok, i dropped my tank and cleaned the breather out. i want to get inside the tank to see if anything is wrong in there. i cant figure it out. any ideas

 

The sender is held in place with a lock ring. There is a special tool that interlocks with tabs on the lock ring to remove it. Most people just use a screw driver or cold chisel with a hammer.

Clean up any dirt/grime and loose rust around the sender before you begin so none of that falls into the tank. Then put the screwdriver against one of the tabs and hit with hammer to loosen. I want to say its like everything else, lefty-loosey, but might be wrong. Spray with PB-blaster, WD-40 or whatever you like first to loosen it up.

I'm not sure what tank PLC was talking about, but every tank I've seen for these trucks has a separate vent hose that hooks to a safety rollover valve in the top of the tank. Gassers have an evap system that collects the fumes and sends them to some fancy charcoal canister, so in essence they only vent through the cap.

My rear tank (before it started leaking) would run a vacuum, I'm guessing the vent was clogged (never bothered checking it), but the fuel filter light never went on. The did however start coming on like you said the other day, I'm hoping its just the filter clogging. Didn't seem to be as much of a problem in the morning, then it was on the way home, and power feels fine. I'm getting a filter and hopefully swapping it this week.

 

well out of all the problems people were telling me what i needed to do. it was just the clogged vent line. i just soaked it in simple green and water for an hour. and then blew it out with an air hose. problems gone

thank you everyone for your help