this post is going to be quite long as i have a few problems that i want help on and im going to give as much info as possible. ok so ive owned my 84 F250 6.9l IDI 4x4 for a little over a year now and up until this week i havent had any problems out of it other than batteries and i did the taraus alternator swap in it. anyways..... were to start.

hmmm well lets start with my idle issue. drove the truck to work friday(25 miles) and it ran fine no problems. went and got fuel on lunch as truck was on E and it ran fine back to work. got in and drove home after work and it ran like crap. seems like it had no power at all every time id step on the pedal it would fall right onto its face and take forever to accelerate. and at idle in gear or in park it idles really low barely enough to stay running. almost sounds like a 8 cyl gasser firing on only 6 cylinders. also never used to smoke at all unless i stepped into it hard or was hauling something(good ol' black cloud. i know its a waste of fuel but i loved dusting out a Prius once in a while!) and now even at idle its a continuous blue/white cloud no black even if im hammering on it

now the second main problem im having is the trans(c6 auto) not wanting to pick a gear and stick with it. mainly when im doin 40-50 it will be in 3rd and randomly downshift to second and not go back to 3rd unless i mash the pedal and then let off. this has been a problem since i got it but it was only once in a blue moon and only if i was doing 30-35mph but it would jump right back to 3rd and stay.

now the idle problem doesnt happen until the engine warms up to operating temp for the first time of the day. then it could sit for 8-10 hours while im at work(plenty time to completly cool down and sit) and as soon as i start it its acts up right away. the shifting problem happens after trans is warmed up but works completly fine until then.

now this weekend after the problems started i though maybe fuel problems were due to running the tank so empty and thought it had picked up something out of the bottom of the tank so i did the following. removed and changed fuel filter. when i put the new one on i filled it half fuel and half Diesel Kleen. then i removed the feed line to the fuel pump onto the side of the pump and took a air hose and blew back through it to remove anything out of the line.(the guy before me removed the rear tank, tank selector, and water seperator. yes the wise guy removed the water seperator! going to get one asap and put it on) then i put the rest of the diesel kleen into the tank, changed air filter(old one was kinda dirty). added some lucas hard shift fix to the trans and some engine/oil stabilizer to the oil. next thing im going to do to it is cut out the "soup bowl" from the air cleaner box so itll help get some air to it.

i know ive rambled on but i put everything on here that came to mind to give you guys as much info as possible. any feedback or suggestions are greatly appriciated!

 

also forgot to add that i did bleed and bleed and re bleed all the air out of the fuel system just to make sure no air locks in there. im thinkin maybe my fuel problem is in my injector pump?

 

Did the diesel clean/filter change help it any at all? It sounds like you got a bad batch of fuel. Try to buy it at places that sell a lot of it.

On the shifting of the c6, I would check the your vacuum lines. Start at the vacuum pump. The line runs off of it, and it likes to rub through from the engine vibration on the inner fender. Then follow it up, and make sure the lines are good. There should be one line that goes over to a gizmo mounted on the throttle at the pump. This device varies the vacuum signal to the tranny, and can be adjusted and can go bad also. Then there is a line that leaves this device and runs down the back of the tranny, and hooks in to the vacuum modulator on the pass side rear of the tranny. There is a short rubber hose back there, make sure it's in good shape and hooked up.

On the water separator. Leave it off. They are famous for leaking air into the fuel system, and the later trucks don't have it anyway. That's why he took it off.