Rockyhud

Hi all,

So here's what's happening. My apologies in advance for such a long post.

I have what I believe to be a fuel starvation problem with my 97 CTD after the engine is warmed up. Below is a summary of what I’ve determined and what I’ve done.

I've been running a diesel/wvo mix (80/20 with Amsoil additives to improve cetane, lubrication, etc) from a local guy for several months now. This has run nicely with no ill effects and several benefits (quieter injection pump, reduced smoke and better exhaust aroma). I don't believe this to be a factor but thought I'd present all the data I can.


Up until a few weeks ago my truck ran great no matter the temperature. Since that time it's started running bad. I’ve taken mental notes on how it runs when the engine is cold (like sitting over night) and after it’s warmed up. In the morning (after a short distance for initial warm up) I can get into the throttle as deep and long as I want or need, making 30+ psi boost and running fine. I travel about 15 miles to work – mostly hi-way miles – and the truck seems to run fine getting me there. After work on the trip home is when I notice the problem - shortly after starting the trip home and getting on the hi-way it can usually build boost up to about 15-20 psi briefly one time then drops quickly and the engine runs rough like one or more cylinders are not firing. I let off the throttle and it smooths out again but only at much lower boost. After that I generally can only get about 5-10 psi boost – trying to get more power/RPMs only causes the engine to run rough again if I apply much throttle very quickly.

This has made me think the volume of fuel to the injection pump is not being delivered as needed until I back off the throttle (less demand to the engine). Further, this makes me think the problem is something that is affected by the heat from the engine.

Here’s what I’ve done so far. I’ve replaced the fuel filter 3 times – one filter was somewhat collapsed but the other 2 looked fine. I removed the fuel pre-screen bowl and cleaned it and the screen – VERY little there to clean out. I tightened the clamps on the rubber fuel feed and return lines (both lines replaced in 2005 with LarryB’s marine grade fuel hose). I replaced the overflow valve - no change in performance. I replaced the 4” rubber hose between the fuel heater and lift pump with OEM hose from Dodge – the inside of one end looked like it possibly might not be sealing like it should, but again no change in how it runs. I also removed the fuel heater assembly as recommended in another forum article, saying they are notorious for air leaks – again no change.

Since the feed and return line rubber hoses are fairly new I have a hard time thinking they have deteriorated and need replacing again, but I supposed this could be true. I've also pushed in on the lift pump primer button while the engine's running and there's no clicking - I've read this could indicate a bad lift pump. I don't have an in-cab fuel pressure gauge so I can't say what the pressure is - I'm considering buying one, particularly if it will help determine the problem.

Most recently I cleaned the engine last weekend so I could get a better idea if I'm dealing with a fuel leak. With the truck parked at home I checked for leaks while it was running. For the first time I noticed fluid around the base of several injectors. There wasn't any fluid between these and the valve covers so I don't suspect a leak from there. I also noticed what I can best describe as an intermittent and very brief, very small jet of fluid coming from near the base nut of one injector when I punched the throttle and let off. Could injectors leaking in this manner cause the kind of power loss I've described? Would heat soak be a factor with injectors when they're going bad?

Again, sorry for the long post and thanks in advance for any info anyone might provide. I generally try to figure out problems on my own (from research and past experience) and not “bother” others like this but I’m starting to run out of possibilities for what’s causing my truck to not run right.

Steve

Rockyhud

Well, wouldn't you know it. After posting last night about the truck and saying it ran fine in the morning (cold) it changed this morning. Just as I was leaving our rural sub-division to head to work it exhibited the same behavior as described on my return home after work trips. There's a slight incline to the road leaving our area and this morning as the truck started to take off up the hill it was making about 10 psi boost when it faltered and started running rough like several cylinders not firing. I turned around and parked it at home. Time to get under the hood and see what I can see. I think first thing I'll try is re-torquing the injectors into the head and go from there. Sure wish I had that fuel pressure gauge installed now so I could tell if the lift pump is working properly or not. I'll update this later after tightening the injectors.

Since I had to take the day off to try to resolve this, if anyone has any ideas to pass along I'll be checking back here during the day and probably throughout the weekend for any replies.

Steve

lifer

With the low milage you have I would say it probably is not the lift pump. I think I would remove the injectors and have them tested at a diesel injection service. I suspect you have a couple dirty injectors. It could still be the lift pump but without a fuel gage you will not know.

patdaly

I am betting clogged/dirty Injectors as well, let us know what you find.

Rockyhud

Thanks for the suggestion, lifer. Would a symptom of clogged injectors appear to be fuel seeping/leaking around the injector nut?

aksparkey01

does it have the symptoms regardless of howmuch fuel is in the truck. possibly a cracked drawstraw in the tank?

Rockyhud

It doesn't matter how much fuel is in the tank. That's one of the things I was took note of too.

I visited a diesel repair shop in town this morning and after going over what the symptoms are, what I've done and mentioning I've been using diesel/veggie mix he said he suspects the problem is one or more injectors has gotten clogged, as several have suggested. He also said he's heard or read that burning veggie oil, over time, can cause a "coking" of the injector tips and suggested this might be my case. Beyond that he said the o-ring seals, since they are original, may have just gotten to their limit of being elastic enough to cope with temp changes, etc., and are now leaking as a result. This shop owner also said the clogging could cause the leaks to be evident externally as mine are doing.

At any rate I bought a new set of injector o-rings from a local Dodge dealer (to be available tomorrow) along with a small wire brush to clean the injector ports and some anti-seize for the threads. I'll be removing and cleaning the injectors and ports this weekend. I'll update this thread once that's done. Thanks to everyone who chimed in with questions and suggestions - they all help sort through things like this.

Steve

aksparkey01

the o-rings are just to keep dirt out of the injector not to keep anything in. and you better have a really small wire brush. couple other things to check are your shutoff solenoid. wire it up on trip and see if that makes a difference. make sure that your getting a boost singal to the afc housing. and check the wastegate to see it its hanging up.
just a couple thoughts.

Rockyhud

Sorry I haven't updated anything lately - wife and I went to Tulsa to visit aging parents over the 4th of July holiday weekend and we just got back late yesterday. Aksparkey01, thanks for the ideas on things to check out. While getting the o-rings and anti-seize compound I also bought a fairly small wire brush to clean the injector bores. I'm hoping there won't be anything that prevents me from digging into this R&R project this coming week after work and this weekend.

So now, here come some more questions. With the injectors out how does one keep any grit and such (presuming there will be some) from just falling into the cylinders - vacuum cleaner nozzle close by? Also, how do you check the AFC housing for boost signal? My boost gauge signal tube is tapped into one of the ports on the intake manifold - do you move it to some place on the AFC housing? As to the wastegate it's controlled by the Turbo-Master boost controller and doesn't seem to be malfunctioning. I don't think the shut-off solenoid is bad as the truck always starts quick and when it's running the solenoid doesn't have any upward travel when I try to pull up on it. And one last question - what's the best/recommended method of cleaning injectors once they're out? I've thought of using a wire brush but I'm concerned about getting too close to the nozzle holes and possibly causing problems due to the wire bristles damaging the holes. I suppose I could take them straight to the diesel shop I mentioned earlier to have them clean them.

Anyway, thanks again to all for your thoughts and suggestions on what the cause of the problem is. If anything else comes to mind, or anyone has helpful hints regarding my questions I'll take them as well.

Steve

Vaughn MacKenzie

Hi Rockyhud, before you go chasing down potential injector issues there's a couple more things to check. First look over your shutdown solenoid and make sure the boot is good, the linkage isn't binding, etc. and it lifts up & down smoothly when you do it by hand.

Turn your key on and bump the starter then go under the hood & make sure it's staying up tight. It could be the solenoid is going bad and after a while it gets hot and starts dropping down, and greatly restricting your fuel supply. This is one theory anyway.

Second thing to rule out fuel delivery problems I'd work on setting up a mechanical pressure guage at the front fuel line fitting on your filter canister head. Tape it to the windshield or something so you can see it while driving.

Another thing you can do is when your tank of fuel is low throw in about 4-6x the normal amount of diesel fuel conditioner and drive it, maybe this will clear out what's ailing it.

I run a lot of bio (basically WVO/DSE fuel) in my '98, I pulled my injectors not long ago, sure enough they were coked with some hard deposits, but it was running like a top, smooth and strong as can be, virtually smoke free.

Another thought on your problem related to injectors. . . if they are partly clogged, or pop pressures have gotten really bad, then you'd see puffs of blue/white smoke when you get the stumbles and misses. If you're not getting smoke then I'd say it's fuel starvation.

Vaughn

Vaughn MacKenzie

Another thought, there is the chance the WVO mix you get is not nice and dry, maybe it had enough moisture in it to do harm to your injection pump, such as galling the plungers and causing them to stick in the bores and not drop down to "reset" and refill for the next injection event, causing a dead miss.

aksparkey01

there should be a tube conected from the back of the afc housing to the intake i bieleve. the stock wastegate line is also t's in right on the back i think. when you start to build boost depending on how the afc is setup or slid foreward there is a diaphram that moves a foot inside the housing. in no boost conditions the foot is all the way back and catches the gov arm before it hits the fuel plate. when boost builds it move the foot foreward out of the way and the gov arm is free to move foreward. so if you want to check this remove the tube on the back, hook up some shop air to it and see when and if it moves. the only thing im not familar with is the boost controller.

Rockyhud

Vaughn and aksparkey, thanks for the tips. Now that you mention it I did see a faint blue/white smoke when the truck suddenly would lose power and stumble. That seems to further zero in on clogged injectors by your description. The shut-off solenoid isn't sticking and the boot is good - I made one from a bike inner tube a couple of years back that's still in good shape. I may try the shop air applied to the AFC for testing it too - good tip again.

I'm researching fuel pressure gauges - so far I'm thinking a mechanical is the way to go as I want one for the interior so this may take a while to get installed. On this topic I've read where some people have bought the tapped banjo bolt for 98.5 and up 24v engines to replace the bolt attaching the injection pump feed line so they could tap for the fuel gauge there. Are these people correct or am I looking at creating another problem (leaks) by using one of these? I'm also considering removing the fuel filter mount then drilling and tapping the appropriate boss. This seems like more work but it sure would make a less cluttered area once it's all done.

I didn't get a chance to find out how much the diesel shop charges for cleaning injectors today but hope to tomorrow. I think I'll see what they'd charge for pop testing them too. If this starts getting too expensive I may consider aftermarket replacements in the hopes I can find some that will provide at least as much power and possibly a little improvement in mileage, if that's possible.

Again, thanks for all the help guys. It really helps to bounce things off someone else or get fresh ideas about solving problems.

Steve

Vaughn MacKenzie

Hi again Steve, using the fitting from the 24v trucks with the schrader valve port is a great idea, because when you go to the auto parts store to get a fuel injection pressure gauge (for gas vehicles) it connects right up to it. I have that on my '98 12V, and use a gauge I picked up at Auto Zone.

Pop-testing should be pretty inexpensive in terms of shop labor, takes as long as screwing the injector onto the test line and pulling the lever. I think my local shop charged around $20-25 to do mine.

jbone

Rockyhud,
My Baby is in the shop getting a new head gasket, and I took all six injectors to the shop today for testing. They all tested low by 400#, so I had them all rebuilt. Pressure testing was free. Six new tips, shims, labor, and all washers and o-rings, with tax, totaled $166.90. I felt this was very reasonable. Of course, I realize that each shop is run and priced differently, but maybe this will give you some idea of what to expect. The new tips were only $14.99 each.

I also had a 93 CTD that did almost exactly the same thing yours is doing. My injectors were sticking sometimes, causing smoking, missing, loss of power, etc. After having the injectors rebuilt, the problem stopped. I didn't think a good fuel conditioner was needed in a truck driven only 10-15k miles a year. Guess I learned something. Good luck.