There's a possibilty that 4.9 FI 6 needs new injectors. Will hooking it up to a diagnostic machine tell that?
If it does need them, how hard a job is it? Something I can do at home? How much should I expect to pay to have it done? Thanks

 

I have a 95 f150 4wd w/ 4.9L 5 speed and I just replaced the exhaust manifold gasket on mine yesterday. I also replaced the injector o-rings while I was in there. It's definately a job. You have to pull the upper intake off to get to the fuel rail. You need a fuel line disconnect tool to unhook the lines to the rail. I started doing it myself then realized it was going to be a lot more involved that I thought it would be so I called my nieghbor thats a ford mechaninc and he helped me out a whole lot.
We didn't need really any special tools other than the disconnect tool and 1-1/16" and 1-1/4" wrenches (I said those cause not many people have wrenches that big)

First I unhooked the battery then I went around and unhooked all the varius vacum lines, electrical connectors, hoses, etc... Now you need the 1-16" wrench to unhook the tube not on the egr pipe on the back of the upper intake. Then we took off the altenator, air pump and the bracket that holds them on, next I went and unscrewed the bolts that hole the upper and lower intake manifold together. We pulled that off then we worked on taking the fuel rail off, unlpugged all the connectors, diconnected the fuel lines then that should come right off and the injectors are just pushed into the fuel rail and you can just pull them right out. Next we took out the lower manifold then the exhaust manifolds.

So figure on a day if your going to do this by yourself, half a day to get it tore down then the other half putting it back together. But for some reason I've noticed you put it back together quicker than taking it apart. I started it at 12:00 and he came down around 3:00 and got done at 9:30, I didn't really write this up as a how-to as I'm sure I skipped a lot of things but I just wanted to write the basics.

 

Pick up a chilton manual. It's a book that every shade tree machanic should have. It will tell you how to do everything. What kind of symptoms was your truck doing to make you think that it was the injectors?

 

At this point, I don't know to think. Truck starts and idles smooth, bucks like a bronco on acceleration or going uphill. Basically any time the engine is under load. Will smooth back out at constant speed.
I've replaced everything ignition wise except the ignition module, which I will probably do next. IF I can figure out HOW to get it off. I bought the handy specialty tool that is SUPPOSED to take it off. Got the back screw out, but the couldn't get the front one out. The socket won't fit in the hole and star tip grabs nothing.
At any rate, I've already put about $100. into this and it only getting WORSE. If it not an ignition problem, I guess the next suspect would a fuel problem. Which leads me to fuel pump and injectors. I already replaced the filter.
Any help appreciated.

 

Before you tear it up to replace the injectors, get a fuel pressure gauge. It sounds to me like a weak fuel pump. PSI at idle should be 55 to 60. If it's low, look for a kinked fuel line, especially in the return. If all else fails, replace the pump. 87-89 have two pumps, the low pressure one in the tank and the high pressure pump is on the frame under the driver's seat, 90 & up have one pump in the tank.

 

My truck studders\bucks like crazy too, so that's why I asked that question. I think there is something wrong with the first cylinder in my truck. The first spark plug was full of carbon. So, I don't know what to do any more.

 

And took mine to a mechanic. The weather finally turned cold and wet here which weaked my resolve to save money, since I have work on it outside. Of coarse if I had done that in the 1st place, I'd have probably SAVED money. Sometimes you win,sometimes you lose. But you always learn.
He ran the codes which said something about the EGR valve.
I guess I'll find out in a day or two.