Hi! I have a 96 F250 7.3L Turbo that I am experiencing problems with. I recently purchased this truck from a friend, and initially it ran great. I do a lot of highway driving with and without a trailer and regularly run on the highway at 85mph without any problems. I had more power than I knew what to do with. Recently though if I cruise at anything above 75mph, after about 2 miles the truck begins losing power rapidly and eventually I will have to pull off the highway because my speed has reduced to less than 35mph. It usually will stall before I come to a stop. After I let it set for a minute or two it will restart after a bit of cranking, initially running very rough, but after revving the motor a couple times it smoothes out and runs nicely. Once I return to the highway I will experience the same problem if I attempt to return to my usual cruising speed. This also occurs above about 60mph when I am pulling a trailer. Another symptom that I have noticed since this began is that there has been a dramatic reduction in responsiveness to changes in accelleration. I have changed the fuel filter several times, changed the oil and filter and checked all the other fluids. I have also pulled both tanks, drained and cleaned them. I have put fuel from two sources into the tanks, assuming that the chance of receiving contaminated fuel from two seperate sources is unlikely, and that if this was my problem I would know where to avoid buying bad fuel in the future. I am recieving two trouble codes , one pertaining to Intake Air Temperature Sensor and Exhaust Back Pressure Sensor. Any idea where I should begin when trying to find a very economical solution to what I am describing? Thanks.

 

Fuel pump. Check pressure/volume.

Bill

 

yep you have a fuel pressure/delivery issue. Have you changed the fuel filter lately? There is also a screen in the fuel pressure regulator that can be cleaned when you change the filter thrut he 1/2 inch hole on the driverside inside the filter housing.

 

Thanks for the quick replies. I have a few follow-up questions. btw, I have changed the fuel filter a few times since this began. The questions:
Is there a simple way to check pressure/flow rate? There is a valve on the side of the filter housing that resembles a inner tube valve stem. Is this for diagnostics? If so how do I go about using this?. Also the screen inside the filter housing... is this located inside the small hole inside the housing, near the top on the driver side? How does one get the screen out to check/clean it?. Is it possible/likely that either of these trouble codes are related to my problem?Also, I am curious about the disk shaped unit at the bottom of the housing... iwith the wire attached on what appears to be insulators... is this the "water in fuel" sensor?
Again, Thanks!

 

Yes the tire valve (shrader valve) is for checking fuel pressure. It works but it pretty messy but you can use a tire gauge to check pressure. The best method is to use a fuel pressure gauge. They are availible at most parts stores. The screen is in the hole you descibed. many use a q-tip with the cotton removed. Just reach in there and gently scrap it clean.

The trouble codes you listed should have no bearing on your issue. But one question does you truck make a strange jet like exhuast noise when it does this.

 

Yea, shrader valve... I knew there was a name for that but couldnt remember it for the life of me. Anyhow, I was unable to get my hands on a fuel pressure gauge compatible with deisel, so I resorted to using the standard tire gauge instead. I took several readings at idle because I was unsure how good of a seal I was getting with the press on gauge. The highest reading I got was 34 psi. I've no idea what I should be getting so I don't know if that is good or bad. As for the jet engine noise from the turbo, I'm actually hearing very, very little of that now, and was wondering why as that type of sound was quite noticable when it was running great, before I began having problems. That is why I thought it might have something to do with the back pressure sensor. Any more suggestions as to where to go from here?

Thanks again

 

Oh yea, btw, I did clean out that screen with a q-tip as was suggested. It did have some dirty stuff on it, but unfortunately after taking a test drive the problems are unchanged.

 

yeah you have low fuel pressure. spec is 40-60 but 60 is the lowest I would want. you probably need a fuel pump.

 

Okay... you certainly know more about this than I (that is why I came here, right? lol) so I'm off to pick up a new fuel pump. Any advice, special tools or problem areas I should look for while doing this switch over? Do I need a new Pres. Regulator as well... or maybe just a pressure regulator? I'm off to the parts store, will check back soon.
Thx again

 

get some kitty litter just incase you spill! diesel can be a menis on driveways!

 

Only special tool other than standard metrc hand tools is a 1 1/4 wrench. You also some 5/16 and 3/8 diesel rated fuel line with pressure rating of 250-300 psi. Get a foot of each and cut to length of the hoses that you will deal with on the fuel pump/fuel filter