i have a 1994 F250 7.3 with an after market turbo. Lately i have to put an additive in the fuel. If I dont there is a miss in drive with the brake on. no loss of power and runs great down the highway or pulling a load. Any ideas????

 

I'd be thinking about getting a new set of injectors(if you can, pay the $300 and get /brand new/ not remanufactured ones).

 

how difficult are they to replace? im pretty handy with gas engines but this is my first run with a diesel

 

Call it an afternoon; I could do it in an hour or so(having done it way too many times).
You will need a 1" deep socket, breaker bar or impact driver, 5/8" wrench, a tub of wheel-bearing grease, and paper towels.

Also, when you get a set of new injectors, make sure to pick up an O-ring/return-line kit while you're at it -- otherwise, the damned things will leak($30-50 though, so not rediculous).

Basically, you will:
1. pull the air cleaner
2. Using your 5/8 wrench, unscrew all 8 injector high-pressure lines from the injector side.
3. Remove the black return-caps from the injectors -- you are supposed to be able to just wiggle them up and off, but I've seen some 25-year-old ones which broke doing it... which is why a new set is a good idea.
4. Remove each injector, using your socket and breaker bar or impact. At the bottom of each injector is a brass washer which you need to get out with it. Sometimes the washer comes out with the injector, and sometimes it sticks in the bottom of the bore.
Last time it stuck for me, I had to use a 1/2" drillbit to get a bit of a bite on it("screwing" it into the soft brass washer with a drill on low) before it popped loose and came up with the drill.
5. Clean the bore with paper towels as best you can; it just makes things nicer.
6. Take each new injector and liberally apply grease to the O-ring area. Apply grease to each of the O-rings, then roll them into the O-ring grooves(Note: Don't use metal tools to do this. I usually just use my fingers and fingernails)
7. Apply grease to one side of each of the new copper washers you got with your return line kit, and use it to stick the washer on the bottom of the injector -- this prevents it from coming off in the bore before you get it in place
8. Put the injector back in and tighten it down. You can look up the specs; I just put a decent ratchet on it and get it good and tight. Note that if it is too loose and the washer doesn't crush, you'll end up with carbon buildup between the seat and the injector bore. Like... solid carbon. Not sure what harm it does, but it's always a good idea to tighten it up good.
9. Coat the inside of each of the new return caps in grease(I used my little finger), then wiggle and slide them on over the injector until they snap down into place. Add your lines between them.
10. Screw the injector lines on, making sure not to cross-thread them. You should get them at least two turns with finger pressure. Tighten them just barely tight, then back off half a turn.
11. Turn the key on, make sure the truck is in neutral, floor it, and give it a few seconds of cranking. Check to see if you have fuel(wetness) around each of the injector lines. As you see it, tighten them down. Once you have 4 tight this way, tighten the other 8 and attempt to start the truck, using glow plugs as-needed. Make sure to keep it floored during this process.

Once it starts, it will be rough for a while until fuel gets through the injectors equally; keep it running oh... 15-1600RPM until it smooths out.

Now, take it for a test run. You'll likely want to time it after this, but you can't do that until it's warm... and you'll know how it performs.
You can then either get it timed 'right' with a probe, or do it 'by ear' based on one of the tutorials around here. I'm partial to timing it 'right' if you've got a new IP, but timing it 'by ear'/by how it performs when you've got an old, worn, or junk IP.

 

Thank you very much this very helpful.... Thanks again

 

Damn, that is a reply WIN right there.