Scotty, I have a 1997 F-350 Ex-Uhaul Box Truck. It has a 460 7.5l V8 motor and an E4OD transmission.
It struggles going up hills and on the highway loses all acceleration at around 55mph and starts decreasing in speed. If i try to gas it back up it just backfires. If i stop and restart the truck it will drive normal again. This is an OBD1 truck. Ive tried a lot of different things. Changed fuel filter, cut off catalytic converter, changed fuel pressure regulator, changed spark plugs & wires, and the previous owner says it has a new fuel pump.
Its embarrassing to admit but this issue started after i was going to change the oil and accidentally drained the transmission. When i started it and it wouldn't move i checked the tranny fluid and thought it had a leak so i put lucas trans fix and supertech mercon v in it. I was changing the oil from 15w40 to 10w30, (another story) so the oils were mixed for a short time and it was overfilled since i drained the tranny and not the oil. i only drove about a few miles with it that way, before realizing my mistake, draining the oil, and refiling it to the proper level. Im honestly not even sure this had anything t do with it but i figured i would mention it anyways.
Before i took it on the highway the first time before my issue started, i added some chevron techron to the gas tank. The truck drove down the road fine all the way to my destination but on my way back is when this started happening. When i changed the fuel filter, it had a lot of garbage in it but the issue still happened, then i changed the FPR and it also had some of garbage in it.
Should i flush the entire fuel system? Could this be a torque converter or other transmission issue? Im really stuck here and dont want to just throw (expensive) parts at it hoping it will go away.
If the engine continues to rev while the vehicle looses speed then it's the transmission slipping or torque converter.
If the engine won't rev, looses power and backfires I would look for a restriction in the air intake system or exhaust system. From your description my best guess is a clogged cat converter.
Never mind the cat. I see you cut it off. There could still be some other kind of exhaust restriction though.
Its your second one. when i gas it it will rev up a little and backfire. Ive cleaned out the cat (still not put it back on) and the muffler is shot so im replacing it aswell. The only things i haven't checked yet is the EGR valve and the smog pump. The EGR will be easy to check, i know nothing about the smog pump and that may be out of my league to try and fix.
Those are both things you should address. I believe a bad smog pump can cause your problem. There is a lot of information available on the internet. It's not very difficult to deal with. Many people appear to delete them. Check this guy out. Good luck.
I went out there and listened sure enough, that pump is squealing bad. I had heard the squealing before but it seems to have gotten worse. My main concern is... i dont know how to take it off. There is a serpetine belt running on it and two other pulleys.. Im still new to all this and been relying on youtube videos to do what ive done so far. I cant seem to find one for this truck. Is there a tension release? do i just slide the belt off somehow? The bolts look like they're gonna be hell to get off, not because of rust but i dont think ill beable to get any leverage on them.
Off the top of my head I don't know if there's a belt tensioner or if the tension release is on the alternator bracket. I will try to find out and get back to you.
Your alternator has a slide bracket that will release the belt tension for the smog pump. Loosen the two bolts and the alternator will rotate. Getting the pump off is gonna be the real battle. You'll need a cheater bar for leverage.
From what I've been able to find out if you don't do a proper delete, which is quite involved, you'll have trouble codes triggered and running issues. The only good options are to repair your pump or get a replacement which would probably have to come from a salvage yard. New/remanufactured doesn't appear to be available. So I hope you can get it off and go at it like dude with the WD-40, hammer and screw driver. Things just get harder after that.
Please keep me advised of your progress. I'd love to know how it goes.
It looks like Rock Auto has a thing where you send yours in to be rebuilt for $114
Sorry, I forgot this part. https://www.rockauto.com/en/catalog/ford,1997,f-350,7.5l+v8,1127102,exhaust+&+emission,air+/+smog+pump,4920
Thank you for that info. Do you have a source for where you found it? The $100 rebuild is not an option. Im way too deep into this truck and im pretty certain this isnt going to solve my problem (but who knows?). It is a fix that needs to be done though, according to research if it seizes it will snap my belt. Im thinking of doing some youtube vids, "rookie fixes his truck"? "rookie fails horribly at fixing his truck and calls mechanic"? haha Ill keep you posted, thanks.
It's really not a lot of information like I said before but there is some. Do a youtube search for 1997 ford 460 air pump, 1997 ford 460 smog pump and 1997 ford 7.5 smog pump. This video is why I said doing a proper delete is involved. It goes from being a repair job to a frigin project. Even though it's a smaller engine than yours it's a similar set up.
I would check the fuel filter first. If it is clean, pressure test the fuel pump. If it is dirty, since you recently changed it, then it shows your fuel system needs some cleaning.
Those are all good suggestions. I would just add that from what I've seen of the condition of the trucks that U-Haul rents out (in a word - awful) I can't imagine what they must be like by the time they are taken out of service and sold. You might want to do a compression test on the engine to determine its internal condition.
