Diagnosis Please? (No Power)

[tugboatphil]

To start, I bought my first CTD in 94. It was a 90 D250 auto with 103,000 miles. I drove it to 304,000 before the 3. 07 rear end was chewed up beyond repair. I was told that the standard "high" rear end had become the 3. 54 and 3. 07 parts were too expensive an option. I started my search for a new (used) truck.



I found a 93 D350 auto in the flatlands of NC. It test drove fine and was in much better all around shape than ol' Blue, so I paid the man and brought her home. When I got back up the Blue Ridge I realized that the uphill power I took for granted on my 90, wasn't there. My fuel mileage, which had been 20-22, was now 13-15.



The truck had set for about a year, before I bought it, so I figured that running it for a while with some injector cleaner would pep her up. I now get 15-16 mpg, but the power isn't there. Here are my symptoms:



- Idles fast (no tach, but it sounds too fast)



- White smoke in cold weather and light gray in warm, upon morning startup. I was used to a small black cloud year round on Blue.



- Exhaust doesn't smell right. I can't pinpoint it any better than that, but it's not the smell you'd expect from a Cummins.



- No "kick down" on transmission. Never had an overdrive, so I'm not sure how it's supposed to work anyway. Going uphill, my speed drops until the OD cuts off around 50-55 mph. When it does kick down, I never get any more speed back up. It just continues at 55. This is with NO load.



I did a CarFax. Com check of the truck before I bought it and it appeared to match the owners story. A horse farmer had it for 4 years and 84,000 miles. The owners brother bought it and then sold it to him. He hauled a dragster on the weekends. When he sold it to me, he threw in a shop manual. The screws on top the smoke screw cover are 1 flathead, 1 hexhead and 2 torx. There is scratched paint around key areas of the injector pump, which makes me think he try adjusting things but maybe wasn't sure what he was doing. I wrote and asked him about it and I never heard back.



I'm heading out of town for a couple of days, in the next day or so, but would appreciate any help that might be out there.



To finish, I first went online in early 1996 and not long after heard about TDR. They sent me a subscription offer. I had never had a problem with ol' Blue and saw no need for it. What a difference my cheapness made. I've learned so much in the short time I've been here and hope to be able to return the favor some day.

 

[Power Wagon]

First: The blue smoke and gray crap means your timing is retarded. This will make it smell like a Detroit. For a real "dirty" check, look at the space between the top of the pump (aneroid housing) and the pump. I can't squeeze my largest finger in the tightest spot. We can discuss the timing thing more later after you look at how the pump is "located" on the engine.



Second: The lack of speed out of overdrive. I've admittedly "tweaked" the pump, but with 3. 55 gears, I can get to just about 80 mph in direct (out of OD).



Get someone to hold the foot pedal to the floor for you, and look at the governor lever on the top of the pump. It should be smashed solidly up against the stop screws. If it isn't, try adjusting the link that pulls it, and also get inside the truck and REEF on the throttle pedal. Pull it upward REAL hard. Don't be surprised if things "give" an inch or more.



Next, you'll want to accidentally "lose" the muffler and the tailpipe, and replace them with free flowing versions. There's normally a "crush" in the pipe right above the axle and underneath the support beam under the bed.



Next, get some Stanadyne Fuel Conditioner - performance formula, and put it in double strength. Then, take a trip. Go at least 300 miles, and preferrable as fast as you can. Work that engine hard, but most importantly, run it FAST and hard. Of course, don't bother, if the timing is off... need to clean up the airflow and all that first, as well.



My truck had done nothing but putt around town for a while when I got it, and it smoked quite heavy for the first 250 miles! Of course, I was leadfooting it across Nevada at 80-90 mph, too.



Change your fuel and air filters, as well.

 

[tugboatphil]

PW,



I checked the throttle linkage and it hits the stops both ways. The cable has about 3/4" slack inside the cab, between the pedal arm and the ball on the end of the cable.



If I did this right, entering the space between the bottom of the aneroid housing and the top of the pump body, I could easily move my finger around.



I'm looking for an exhaust system that won't require too much additional work, other than installation. On that note, if my engine is stock, what size turbo housing do I have, and will changing to a smaller one affect the exhaust hook up?



I have changed all filters twice in the last year, and I think the new fuel filter helped the mileage as much as anything else.



Going by the fuel/smoke/idle adjustments that I found around here somewhere, do any of these need to be made while idleing? It doesn't say one way or another... . I think. I'll have to find my copy.



Thanks for your help. When you said the exhaust smelled like a Detroit Diesel you pegged it! I couldn't explain it, but that was it.



Lastly, my truck is my office/work. Whenever it's down, I'm unemployed, so I'm hesitant to screw things up too badly. There is a Cummins garage within 40 miles of me. Do you think I'd be better off getting them to set things "stock" before I give it a go? I was a mechanic in the Army 25 years ago, but since the use of fuel injection, I'm even scared to tear those things apart. Is this stuff as simple as it sounds?



Thanks a bunch for your help!!

 

[Power Wagon]

The symptoms you describe sound like the timing is off. OR, you could have bad injectors.



Pull the top cover off the diaphragm and see if the plunger slides up and down freely. It should. There should be vague "mechanical" feel as it comes back up. theoretically, there's a pin being pushed as it slides upward.



pull up the diaphragm and look under it. It should free of dirt, but lubricated. No signs of rust or gummy stuff. Sometimes they have grease under them. Spray some WD40 under it and onto the plunger.



You can test the operation of this device by removing the "U" shaped pipe that runs between the head (intake area) and the top housing (about 3 inches long) from one end or the other, and driving the truck. With the pipe totally disconnected, there should be a serious power loss. If not, you need the services of an injection pump shop.



You seemed to indicate this truck has well over 100K miles. I would replace the injectors, since it appears the previous owner used it rarely and didn't seem to work it much. That is very hard on injectors. Since new stock injectors and new PW injectors cost about the same, it's a great upgrade just for doing normal service.



The easiest way to fix the tailpipe is to go to a muffler shop and have them put a new tail section on.



I just elimenated the muffler at the same time. Muffler shop put in a chunk of pipe which was bent slightly at one end.



Changing to a wastegated 12 DOES affect your exhaust pipe setup. The housing is roughly 1. 5 inches longer, when using the adapter to fit your downpipe. Otherwise, you use a downpipe from a later truck. That's mine below.



#ad




There is a "bullet" shaped anti-tamper seal on the high speed stop screw. That's the one on the side that's easy to reach



It should have no more than perhaps 1/4 inch of threads between the last housing boss and the end of the screw where the lever touches it. If there is no anti-tamper cone, just give it a few more rpm by backing off the screw.



There is also a somewhat complex anti-tamper device on the fuel screw, as well. If it's missing, there should still be a tacked-on collar and washer and nut between the collar and the pump housing. If the collar is missing, no way to know where your fuel is set. If it is there, the screw should be in as deep as possible.



I'll let you c heck the pump position the quick'n'dirty way, and then I might suggest you move it.



Is there black paint on the injectors, above the retaining nuts that hold them into the head? (paint flakes off). If they are gray, rusty, or black (not paint), they have been replaced. If they are black, but do not have paint (chemical blackening treatment), they are probably some kind of rebuild. I would put in new, in that case.



And no, for the most part, I do not suggest taking it to Cummins. They know the engine well, but for the most part, the mechanics haven't a clue on this engine - performance wise.



Cummins shops near us (when I worked in a pump shop) thought the magic bullet was to pull the pump in all cases, it seemed, and bring it to us. They did NOT understand the finer points of tuning and tweaking.



Your truck should have the 18. 5 CM exhaust housing if it is stock. It generally doesn't make much for boost until you get rolling down the road a ways. My 12 will spool right up and give you boost right off the line.



There are some tweaks you can do to the transmission shift stuff, but I'd ask hdm48 to explain it all. He's got it down real well.

 

[tugboatphil]

PW,



You've given me quite a bit to go on. My work is coming over the fax right now, so I'll be on the road until late Saturday. Sunday will be for recuperating. I'll start surgery on Monday and let you know what happens.



One more thing. Are all these adjustments done while shut down? Is idling required for any? Are all these adjustment areas dry (do I have to replace gaskets?) I guess that's more than one thing.



I certainly appreciate the help!

 

[fest3er]

Originally posted by tugboatphil
P... I'll start surgery on Monday and let you know what happens. ...

Let me know if you want/need an extra pair of eyes/hands/feet. Or if you just want someone to kibitz and fetch tools.

Fest3er

 

[Steve Campbell]

I know I am in the wrong forum....

but... . Power Wagon, that was an awsome response!

 

[tugboatphil]

PW,



I finally got under my hood and have achieved some improvement. Fest3er came up and was very helpful in pointing me in the right direction. We pulled the diaphragm and according to the printout I had, it was set on minimum fuel. We looked to where the fuel pin would have the most travel and it ended up being 180 degrees off where we started. A quick road test showed some improvement, but hardly noticeable.



We double checked the throttle linkage and it seemed to be as tight as it could be. My full fuel screw was missing the collar, so I'm guessing it wasn't cherry. After backing off the locknut, we turned it in (CW) 3/4 turn. Took it out and it made a BIG difference. Since I don't have a pyro Fest3er suggested I not go too much further in with it.



We looked at the pump, and read through what the shop manual had to say. Got to looking at the scribe marks on the pump flange and gear case and they were already off. At some point the pump had been turned toward the engine about 3-4 degrees. We didn't have a proper tool to get at the bottom and back nut, so left it alone. I may take it to a shop and get them to set the timing and get the pump tested too.



Anyway, the hill I used for comparison showed me the improvement. Previously I could get a good running start at it and before getting to the top it would drop out of O/D and slow to 50 mph. Even dropping into 3rd would not give it any power. Today it never dropped out of O/D and after topping out at 72 mph, it slowed to 62 and held steady.



I'm almost sorry I went through this because I'm ready for more power. Unfortunately my wallet isn't... . I don't really need to heat the house this winter!



Thanks for all your help, and if you'd care to comment, I'll appreciate that too.



Thanks again to Fest3er! I was complaining that the instructions weren't worded clearly and he told me I had the paper upside down!!

 

[BushWakr - RIP]

Just curious, but how's you tailpipe smoke now??

I'm surprised you didn't see more improvement when you moved the diaphram to max.

PW, why would that not result in a more noticable improvement? Would there be an internal issue that would minimize this adjustment??



Bob

 

[tugboatphil]

I'm getting a small cloud of dark gray to black when I start up and when I take off with WOT. I tried turning in the smoke screw a turn, but that seemed to take away a little bit of power.



Is this a pump timing problem?

 

[BushWakr - RIP]

As I understand it the 'smoke screw' is simply a bit of "pre-load" on the diaphram.

This adjustment affects your initial launch feel/smoke. Ok, that's not very technical but I found that my "across the intersection" response dropped when I turned it out ( CCW ). Basically its your "0" boost fuel and provides that "puff" to get the turbo spooling.



Someone correct me if I'm wrong here...



bob.

 

[fest3er]

Pu edis-thgir egap eht nrut.
Snoitcurtsni eht gnidaer:



I'm going to guess the pump needs a good timing job. I could easily fit a finger or two between the AFC and the head. The pump was set about the middle of the adjuster slots. And givine where the scribe marks were, I *think* that may be a different pump than original. After the engine was warm, reving it up to max in neutral generated a fair bit of white smoke - not a dense fog, but unmistakeable. Since I figured the engine should be warm enough, I didn't try it right after a test run.

Before the adjustment, the truck accelerated; it wasn't as bad as my '98 12V with no boost to the AFC, but it certainly seemed lack-luster. After adjusting the eccentric, there was a little change, but not much. I *think* there would be a puff of black smoke just before it up-shifted, then it would returh to a bit of haze.

After turning in the power screw, the haze was a *little* thicker, but not much. It still hardly smokes. And I definitely got pushed back into the seat.

So, Phil's got some more power. I'd suggest running it for a couple weeks to see if the mileage changes.

What kind of tools are needed to loosen the 3 nuts attaching the pump? Sockets don't seem to fit (though we didn't try a uni-joint). , wrenches can't get in.

You know, we never did adjust the smoke control, but given the slight haze, perhaps it's about right... .

Fest3er

 

[Power Wagon]

Move the pump already!!!



Every symptom is one of severely retarded injection timing. My truck will put out a LITTLE bit of blue if you start it up cold and gun the engine a little.



After the engine has run for 2 min's, it won't smoke at all to gun it. And that's with the bigger PW injectors, and bigger injectors definitely smoke more.



I can't get my index finger in between the the aneroid housing and the head while holding it vertical and sliding it from front to back. It's close, mind you.



Do that, and it'll probably get rubber

 

[BushWakr - RIP]

I really thing PW is right on the money re: timing.

One of the "general rule's of thumb" that has worked out pretty consistently is moving the pump mark, up about 1/8" from the original line-up marks. It seems that this comes very close to 15* advance, + or - a very small bit.

I've looked at a number of 1st Gens and they all seem to be right around that amount.



As for the kick down... I'd check the 'infamous' TPS', and the throttle valve cable setting.

The TPS voltage "at rest" invariably seems to be best around . 5 - . 8 VDC. and when the throttle is slowly opened up to WOT you should have a total increase of 2. 25 - 2. 75 VDC over 'at rest' reading. The TPS governs the 3-4, 4-3 shift. The higher the starting VDC the later the up-shift happens. At too high a setting it also makes the OD drop out fairly sensitive so watch for that.

If you need more detail do a search for TPS. If you can't find the instructions I posted, let me know and I'll PM them to you.

Lastly, the transmission has a thermo-switch on it. If your trans temps reach around 270*F then the switch forces OD out, and will prevent re-engagement until temps drop.





Bob.

 

[XGoldman]

For getting to the pump attachment nuts you can't beat the Snap-On wrench. Sorry, I can't find the part number.

This wrench will save you loads of time,cursing and general frustration. I ordered mine online. Other than guages this will be one of the smartest purchases you can make for your truck.

 

[rwinslow]

Try the following part number:



SP 144, Cummins Diesel Injection Pump Wrench



Snap-on web site



$22. 55 plus shipping and sales tax.

 

[tugboatphil]

PW,



I finally got the 3 bolts on my pump loose, but I can't turn it. With all those fuel lines hard piped, is that whats stopping me? Am I supposed to loosen something else? Am I brain dead? I turned the full fuel screw in another turn and it's noticeably better, but the fast idle is still there and it doesn't yet sound/smell like a Cummins.



Phil

 

[BushWakr - RIP]

Turning in the "full fuel screw" does "trick" the pump a bit and results in a higher idle. You can adjust that down.

When you do bring it back down, just make sure that the stopplate touches the low idle screw end, otherwise you may need to adjust he linkage a bit.



As for the pump not moving, I'd defer to PW on that one, but get the timing done before anything more is adjusted.



I know when mine was done the hard line at the front of the pump was loosened a bit, as was the 6 fuel lines at the back, but just a tad.



Bob.

 

[Power Wagon]

Did you get the bolt underneath the pump that's just below where the lines enter? It goes through the flat plate attached to the "front" (where the lines hook up) of the pump and into a bracket bolted on below the pump. It requires a 10MM wrench or socket.







There's also a U shaped line that runs over to the intake, and it can be provide quite a bit of resistance to moving the pump.



Generally, it takes some pretty good force to make it turn. If hasn't been loose since the the engine was built, it may need to pried away from the engine to break it loose from the gasket.

 

[Steve Campbell]

When using the 1/8" rule....

you wind up turning the top of the pump towards the engine block??? At least that is what I gather by reading this thread.