I'd like to change the fuel injectors in my '94 300. I hear alot of horror stories of bolts breaking of, pieces cracking or threads stripping when taking off the intake and throttle body. Is this risky business? What kind of steps can i take to make this job a little easier? Comments greatly appreciated.

 

I think the TB is Aluminum, if it isn't, it sure is soft metal anyway, you could easily strip the threads, be very careful when re-installing the bolts that hold the upper plenum to the lower. Although it is a pretty easy job, you must be very careful not to break the vacuum lines, they are plastic and brittle, I have busted a few lines in my truck and it starts to look lousy when there are too many rubber hose splices in there.
The fuel line and return are hard to get to and sometimes difficult to break free with the spring-lock removal tools. Maybe you could just leave the Fuel rail connected to the lines and push the rail and lines out of your way while the injectors are getting plugged into the manifold.
While you have the upper TB off, it is a great time to change the valve cover gasket, I think the rubber gasket is pretty standard there. You will have to disconnect the EGR valve, I would just take the two small bolts off the EGR, instaed of unscrewing the valve from the pipe. The throttle cable is delicate, so remove that from the TB very carefully.

When reinstalling the injectors make sure you do one at a time and pay attention to the routing of each injector input plug, keep the wires slack and don't pull on those wires, pull on the plug only. You may need two small screwdrivers to pry the connectors off.

To pull the rail off, start pulling gently in the front and separate the rail slowly from each injector, one at a time, being careful, not to bend the rail!!! Work your way from inj's 1 to 6 and carefully move the rail to the side. You should be able to leave the fuel regulator on the rail(don't break the vacuum lines running to and around the regulator!!!!) I think you may have to unplug one or more connectors as they may run over the top of the rail, take a picture of the area to be sure to route all wiring back to its original position.The rail is made of good strong metal piping, but can be damaged ( kinked).

The rail can go back on after you have inserted all the new inj's into the block. When re-installing the rail you will have to carefully coax the rail back onto each new injector, and gently work the rail from front to back several times as you align each injector and work them into the fuel rail a little at a time.

 

I just rebuilt a 1995 300 for my E150. Just replacing your injectors should be no problem.

The air injection tubes into the heads will give you a serious fight. One of mine broke off in head. Major nightmare. Exhaust Manifold studs need major heat to come out. EGR tube connections needed to soak in WD40 for two days and used heat to disconnect. EGR bolts broke off in upper intake and had to be drilled out and repaired with helicoil.

Hell replacing my fuel injector o-rings was the fun part after all that.

 

Not all 4 9's have the air injection tubes, mine doesn't and I'm thankful for that. I swapped engines in my 92 last year and didn't break/strip any fasteners. If you are worried about stuck bolts be sure to use "PB Blaster" spray-on penetrating oil, it is good stuff.
Be aware that varnish from the fuel makes injectors and fuel line connectors very tough to initially break apart or take out, the varnish is tough and acts like glue.

 

Air injection tubes? Are you guys talking about the tube from the exhaust to the egr valve? I'm prerry much a greenhorn when it comes to workin on motors but I've pretty much come to the conclusion that i should do it myself. I got leaky injectors and a real BAD vaccuum leak. Im very thankfull for this forum and its amazing how much I've learned, and how much info from everyone's combined knowledge. Alot of the mechanics up here like at crappy tire and tittle business dont know a hell of a lot, or just don't care. Like replacing parts that dont need replacing, or until they finally replace charge you for new injectors, FPR, fuel rail and lines, selector switch and fuel pump before they find it was just a clogged hose or something. No autozone or big box stores like that, cant even get seafoam to see if it might help the injectors. Napa dont have it, canadian tire, might have to drive 3 hours to duluth MN,. Does anyone know if they got an autozone?

 

Yeah, the one from the manifold to the EGR valve can be a hard one to break. The egr tube runs between the last 2 intake tubes, so you will have to take it loose and pull it up out of the way. I had to crawl up on top of the engine and pull to get it to break free. Use high temp anti-seize when you reassemble so it will be easier next time. Unless you want to change the TB gasket, you don't have to take the TB off the manifold. If it's never been changed, go ahead and do it too, along with the IAC and EGR.

 

Ya that egr tube looks like a pain to take off. The friendly neibourhood muffler shop took the old stock exhaust and put a y pipe in from the exhaust manifolds, when they changed the burnt cat that i had for some time. They had to play with the egr tube, notice a gasket missing between the egr and the intake manifold, unless there never was one there. Its been runnin a little rough at idle ever since, with a bad miss, idle rpm up a lot. Hopefully i'll find a vacuum leak somewhere, as for the throttle body, i guess ill change that too. I hear whistling noises when i let off the gas, and when i hit overdrive i start hearing a weird Buzz like noise, right behind the radio, kind of sounds like if you put a thin piece of paper right at the tip of a moving fan. Im wondering if because the rpm is up with the vaccum leak, im hearing the airpump or something. This truck's got a lot of problems.

 

The buzz behind the dash(radio) may be vacuum. The air (hot/cold) blend door does operate by vacuum. Find the white vacuum hose on the passenger side near the hood hinge, it should be up close to the passenger fender and up high;You'll see it disappearing into the firewall somewhere, the white plastic hose is notorius for rotting and breaking. Pull that hose off your manifold, wherever it seems convenient, and plug up the manifold port so it does'nt leak. If the buzzing goes away maybe there is a leak back there.
I believe the controls for the cabin air temperature under the radio have two or three vacuum lines there. Has your truck been freezing in the winter and hot in the summer? Could be a sign the blend door never quite switched all the way, leaving you with a mix of hot and cold air all year round.

The EGR does need a gasket between the valve and manifold, get it, and install it. If you try to loosen the EGR from the tube you must pre-spray the threads with "PB Blaster", or a really good penetrating oil first. You need some good wrenches also, the force must be on the hex nut and valve, not the tube.
Get a cheapie $30 dollar vacuum gauge/vac tester, it is a great tool for post 70's vehicles, which happen to thrive on properly rigged vacuum systems. With that tool you can test the EGR, vacuum reservoirs,(there are two reservoirs). air bypass valves, any line you wish, and most of all it is good to know how much vacuum your are pulling thru the manifold, a test that truly helps the home mechanic determine the health of an engine. My new rebuilt I6 is pulling 22"Hg Here is a little clue..This component screwed me up for years and I didn't know it was so critical.."The coffee can" on your passenger side wheel well splash shield. This is a poorly painted metal can that eventually rusts out and causes a vacuum leak, it costs 35 bucks at the dealer if yours is leaking.

Can't stress enuf the need for good tools, if you must, borrow them from your friend, or local auto parts store, or put them on a credit card. It is no fun working on these trucks without a good selection of tools. Good Luck

PS "Air injection", there are two kinds, there is a system out there with 6 tubes running into the side of the head, these tubes feed fresh air from the smog pump( below alternator, has big fat hoses in and out of it) and into the exhaust ports at each cylinder. I don't mean the large intake and exhaust pipes either, these would be about an inch around.
The second system which you probably have is the single tube, this is recognized by finding the large air valve with a filter on it that is postioned over the top of the alternator, the tube then runs straight back under the 6 plenum intakes and drops down to inject frsh air right before the first cat. This fresh air is mandatory for the CAT to burn up the exhaust gases effectively, without the fresh air, no chemical reaction happens inside the CAT and it will eventually clog.
Now I wonder if you even have a working smog pump????? I didn't like that little fact you dropped about the burned up Cat you already had. I'm sure a reputable muffler shop wouldn't have installed a new CAT without making sure your smog pump was working. BTW the the air from the smog pump is controlled by a realy that uses VACUUM if there is no vacuum reaching the air injection relay or the air bypass valve then you will fail emissions or kill another cat.
The EGR tube of course, runs straight up from the exhaust header to the back of the intake plenum where your EGR is. There is only one EGR tube in the truck.

 

I kind of wishedi just took all that californicated stuff off my truck to start with. That rattling clogged cat that i had before could of just been an indication of a another problem, like running too rich, or related to leaky injectors? Mabey that motor has a drinking problem.The only think that i noticed about the smog pump i have is that the pulley is warped pretty bad and it is pretty loud. You should hear the motor, its the loudest inline 6 ive ever heard. Some guy from worked joked about! Says what you got in there, an electrolux? Gonna have to put some overtime on this job, pretty new to all this stuff.

 

The rattling coming from the CAT (clogged or not) is probably just rusted out u-nuts-missing bolts on the CAT heat shield. The CAT gets extremely hot!! So the CAT is always covered with a clam-shell like metal shield that keeps grass and other combustibles from touching the metal skin of the CAT. If you crawl under the truck you may find one or two bolts missing from the shield. Go to the auto parts store and buy new stainless steel u-nuts and bolts. If you see some holes in the shield where it looks like there used to be a nut and bolt, then that is your problem, cause the only holes in the shield are for fasteners. Ford placed those u-nuts all over the truck, they hold on bumpers, brackets, shields, etc. the main problem is that the u-nuts are made from stamped thin metal, the u-nuts are not as "beefy as a standard hex nut and when corroded they tend to fall apart quickly.

About cab vacuum again, I was probably wrong about the white vacuum hose being the source for vacuum to control cab air. I just looked at my 92 truck and there is a white and BLACK vacuum that go into the firewall, I believe the black line is the main source of vacuum for your temperature controls.

Get the smog pump pulley fixed, it is wearing out your serpentine belt.
The smog pump is easy to check, there are two hoses an intake and output,
find the hose that goes to the CAT eventually, (the output should be going to a valve) remove the hose from the air bypass valve and start the truck, you should be able to feel the air pumpimg out of the hose, it isn't high pressure, but should be coming out with some vigor.
I recntly replaced my smog pump, it was $58 for a recon. They don't come with pulleys, so you may need to buy a new pulley, the junkyard might be a good place to try first.

 

Hey beatupford,

924x2150 just gave you a wealth of information in this thread on how to get your truck running like it should.

Go with what he said !!!

Kudos to you 924x2150 !!!

Good topic and discussion !!!

Bob

 

These are all problems I've had to deal with the last ten years. I hate having stupid little problems with my rides and I hope we all can help each other.

 

Thanks for the info. I'llkeep you posted on what happens. I've been dealing with this for about two years now. You know I haven't even mentioned the gas smell in my oil from the leaky injectors, dont think its the fuel pressure regulator. The vaccum line to the FPR dont have gas in it or anything. When i start it up though you can smell the gas from under the hood. I also get condensation in my oil from one or more of the vacuum leaks. Hopefull all the sawdust and road dust is keepin some of those vaccum leaks from gettin worse! Man id love to just strip this motor down and start from scratch if i could.