Hi Guys,
My truck has been running rough for a few months and I think I've narrowed it down to injector #8, but I'd like some input before I replace it.
The truck is a 2000 F450 manual with 210k on it. I bought it last year at 207k. The PO told me the injectors had been replaced about 10k before (by the owner before him, so it can't be confirmed). It seemed to start and run fine last summer/fall, but when it started getting colder it didn't like to start. Did some research and chased things around (replaced GPR, glow plugs, UVCHs, CPS), with no improvements. Did a buzz test and contribution test, with #8 failing the contribution test. Also when I was replacing the glow plugs, I noticed that #8 has a different color plastic top than the other 7 injectors (which all have an R on them). My speculation is that whoever replaced the injectors replaced them one at a time as they went bad, or just skipped #8 for some reason.
I also checked the fuel tank and it is very clean inside with no flaking or clogged screens. I added a fuel pressure gauge on the output side of the fuel bowl and get about 55 psi at idle and 50 or so when I put my foot into it.
On a day like today (50s at night, 70s during the day), it will start after WTS, and run, but it has a definite shake/miss to it, which seems to lessen when the engine gets up to temp. It also seems to lack power until the engine warms up.

I am planning on replacing injector #8 with a new, stock injector.

Thoughts or comments are welcome, and if anyone has a link to an injector replacement how-to that would be awesome.

Thanks!

 

It does sound like a worn injector, but before pulling the #8 injector out do this one simple thing. Remove the solenoid and the spacer under it. Using a set of feeler gauges, see what the thickest one you can fit all the way around between the armature plate (the square plate with the screw in the middle) and the poppet body is. Start with .0015" and work up from there.

What happens as the poppet seats wear is the armature plate to poppet body clearance slowly decreases. When the clearance gets down to about .0015, the oil trapped between the armature plate and the poppet body causes a suction, and the solenoid can't overcome it as easily. As the the trapped oil warms, the suction is easier to break and the injector starts to operate.

The different looking solenoid connector on #8 is usually seen when that injector has been replaced with an AE long lead injector, which Ford installed as a (sort of) cure for the knocking noise known as fuel cackle. The R on the other solenoids does indicate the injectors are rebuilt.

 

"R" as in Remanufactured.

Your #8 could be a bad injector, or it could be excessive air in your fuel (#8 always gets the air). If you have a lot of knocking, smoke, and bucking with light acceleration or on a hill climb - it might be a simple loose injector.

What symptoms do you have besides the shake and miss? Do you have AutoEnginuity or another scan tool... or did somebody else test it for you?

 

In my experience "R" stands for junk. Good to hear you are buying new.

 

To clarify, unless the truck is modified #8 injector is always different than the other 7. It has a different part # and could easily have a different color top. As our yellow anime friend says it is a "long lead" and it operates slightly differently. It will almost always show as bad on a contribution test for this same reason. Do you have the numbers for the test? IIRC 5% - 6% is considered normal for #8. Kinda like oil consumption of a quart per 1k miles is normal. Not good, but normal.

When doing a buzz test cold, how does #8 sound? Same as the others or weaker? Weaker is bad, obviously. And how does it sound when performing the buzz test hot?

Overall given all your diagnosis and repars I think you and the FTE Brothers are prolly right about the bad injector. But before spending the time and coin on a new injector, further diagnosis might discover the problem is easier and cheaper than it looks right now.

Additional thought: what brand glow plugs did you use? Autolites have a bad rep.

RiffRaff Diesel has some good instructional pdfs, including injectors, check out this link.

 

I forgot to mention - I have useful links in my signature.

 

Pikachu - thanks for the tip. I will try that when I get a chance. If the injector is not worn as much as 0.0015", then could something else be causing cylinder #8 to fail the contribution test?

Tugly - I'll have to do some research on how to check the tightness of an injector. I don't have AE; I took it to a local mechanic who scanned it for me. The only other symptom I've noticed is some white smoke on startup (and when it's cold - like below 40F). I think I do have a little blue smoke under load, but I haven't been able to observe this closely.
I have looked at some of the links in your signature before - very useful!

Jetdoc - that's what I've heard!

aawl - I realize that inj #8 is different, but I was assuming that if someone had replaced all 8 at the same time that they would all have an R on them (maybe that's not a good assumption!). I don't have any numbers from the contribution test. I'm planning to have it retested soon since the first test was a while ago and I'll see if his scanner gives percentages.
At the time I didn't know what to listen for during the buzz test, so I can't answer those questions...
I used Motorcraft glowplugs, since I had read about the autolites.
I will check out the info from Riffraff.

Thanks everyone for the input!

 

"Injector tightness test": Pop the valve covers off and check the torque on the injector hold-down bolts, to see if they all go to a naked minimum of 50 in/lbs. Once checked for minimum torque, they should be set to 120 inch/lbs - according to the book... but I use 130 in/lbs.

If you have one or more below 50 in/lbs, the book says the loose ones gotta come out and have new O-rings/copper washers installed, and I agree - after my experience with this.

The tools that make setting torque easy:

1. Inch-pound torque wrench (240 in/lb. max limit is ideal).
   1A. 3/8" to 1/4" drive adaptor if the torque wrench is 3/8" drive.
2. About a 6"-long and a 12"-long 1/4" drive extension.
3. 1/4" universal joint.
4. 1/4" drive by 8mm deep socket.

A number of members have had injectors come loose after replacement - and I'm the grand poobah of loose sticks - my torque wrench is my scepter.

 

Before you pull anything ; check the wiring inside the wire loom where it splits off from the glow plug relay. I went through 2 # 8 injectors at the ford dealer because it was reading a code. I found it by accident resealing fuel bowl lines. 2 of my wires were shorting out the glow plugs causing havoc in the computer. Sorry I got here so late.

 

Cylinders #3 and #8 have a tendency to fail CCT if you have a cam sensor that's anything other than an OEM black one, and those are getting pretty scarce.

 

I had a mis behaving #8. I wanted to swap #4 and #8 injectors to see if the problem moved with the injector. When i pulled out #4, By Chance, Luck. #4 had a really bad oring. Put new orings on on both and no more issues. I speculated that #4 was pumping in air and #8 was yelling.

 

It's more likely oil was feeding into the fuel line and 8 was getting the oil from 4... unless the copper washer was leaking. If that copper washer is compromised, bad things happen: Exhaust gets into the fuel rail and wreaks havoc - because unfiltered soot and air reaches the injector nozzles, as well as the pressure shock to the fuel line.

 

Good idea, I'll check that too.

I thought that might be part of the problem, so I tried replacing the original with a new one (gray) which didn't make a difference. Would a cam sensor cause it to run poorly, or would it just fail the CCT?

 

Going to get a CCT done today - I'll post up the results.
On another note, when I do order the injector, should I get it from Full Force Diesel, or get the Alliant from Riffraff?

 

The are all Alliants - the only real difference is reman vs. new. They didn't build these trucks with reman parts, and they last a good long time with proper parts. I went with 8 remans, then immediately swapped for 8 new injectors - big difference. It will sound a little odd with one "crispy" injector and 7 "thudders".