Very Poor Power!!!

[onedaysoon]

Hello all,
I am a proud owner of a '96 F-250 Supercab with 4.10 rear end and Automatic transmission. No modifications have been made to the vehicle. It only has about 47,000 miles on it and has been very well taken care of. The problem is that I just purchased a 35' tag-a-long camper and took it through the mountains of West Virginia up I-79. I expected it to pull down on some of the hills, but I did not expect 35 MPH. Even when it dropped out of over drive it continued to lose speed going up some of the hills. When going back down the hills which some were 5% grades warning truckers to use lower gear, I had to keep my foot on the pedal to keep going. If I took it off the pedal the truck would begin to slow down rather than speed up. I really think something is wrong. The air filter is clean (recently changed). Is this performance normal for a stock truck or am I right something is wrong?
Please help
Thanks
Brian

[breuer69]

Fuel filter been changed recently? Also with those few miles on it it could be an issue with the turbo or something sticking.

I'm sure one of the more knowledgeable 7.3 guys will chime in but here's a

[breuer69]

oh, and

[blizzardwarrior7]

Fuel filter, bad lift pump in the valley, bad thermostat.

[outlawdiesel]

well you got to give me more then this.is there anything wrong other then being stock the hp for obs is only 200 or right around there.are you losing power driving around town.is there smoke.

[onedaysoon]

Ok, as far as fuel filter it was replaced the same time the air filter was which was less and 5,000 miles ago. If the thermostat was bad, would the temp gauge read high? If so I don't think that is it since even when in a hard pull with the high outside temp the never went above half way on the gauge and when not pulling it stays below the n in normal. Is there an easy way to tell if the lift pump in the valley is bad, and where is it???
Don't know much about working on one other than maintenance.
Haven't noticed any power loss around town, but you can tell it doesn't get driven much, used mainly as a farm truck. I know a waste of a good truck. During cold weather or cool weather, I can feel a big lug on it at certain times and it makes kind of like a hissing noise when it does this but I figured it was part of the cold engine sequence to get it warmed up, but it does seem a bit excessive and I don't remember it always doing that. Also I have not noticed any smoke, however it has been quitting without warning here recently. When it quits sometimes it takes a little to get it started again. It quit right before we left on vacation and did not quit at all on the trip.
Thanks for the quick replies.

[blizzardwarrior7]

First off, dont go by your dummy guages in the dash....They rarely ever work. Secondly, fuel filters needto be replaced more often on diesel vehicles than gas ones, and it would definitely be worth replacing it. The lift pump is right in the valley of the V. Disconnect the outlet of the pump and make sure its actually pumping out fuel.

[stewy]

does your truck have an exhaust back pressure valve that could be stuck?

[outlawdiesel]

well it sounds like your exhaust is leaking.up pipes or exhaust manifold.look at exhaust manifold and look for black powder and check donuts on uppipes.motor got to be cold and feel in back of turbo and you should feel 2 pipes and the Y going to turbo and if your hand is black with black powder that would be it.but i think its not one thing, it might be acouple things.so this truck sit on the farm.when do you use it?

[onedaysoon]

Flyin hawaiian, I will have to check those things out and will let you know what I find out.
Stewy, I don't know about the valve, but that is kinda what I was thinking.