AFC pin

[EZeis]

Hello

I've read about the fuel pin sticking and no power. Can the pin stick the other way and cause more power, engine noise (detonation), and more smoke then stock pump settings? It's a stock pump, settings all sealed still, and pump timing 1. 40mm. Truck sounds great, runs great, and such. But about 2200RPM to 2400RPM I get this detonation/nozzle knock. Below or above that area, everything is normal. Two of my friends, their trucks sound like a diesel and then that diesel noise goes away and it's just a smooth roar. My truck, it sounds like a diesel clear up the RPM range. Thought it was worn injectors, new ones didn't change it. I try to keep below 2200 as it doesn't sound good for the engine. Also, if I punch it and bring it up past the 2200 to 2400 range, it's just a quick noise and gone. Also it causes a vibration through the throttle pedal. Truck has a lot of power that I never use and way more then my friend's trucks. Any ideas? Thanks!



Earl

 

[Greenleaf]

I'd of thunk that someone with more knowledge would have offered some suggestions, by now.



I do not know. These are my thoughts.



The KSB valve and related components. The pump may be turned up and the tamper shield re-installed. You are off on your timing check(?) and timimg is way off (advanced)



GL

 

[EZeis]

Gl,

Yeah, I figured I'd of got a pile of replies. The pump is a reman with the goo stuff to tell if pump has been tampered with. Timing is 1. 40MM checked with the correct tool. I have check the pump mounting nuts and the rear bolt. Cummins states that you can have vibration problems if the rear bolt is loose or missing. I did notice one of my power steering pump to vacuum pump stud, spacer, and nut is missing. The missing hardware also holds the support bracket that comes from the block, maybe that's my vibration problem? I've ordered new hardware, so I'll see if that fixes it.

KSB system working correctly. I even unhook the KSB and still there. Does it cold, warm, hot, empty, loaded.

I'm thinking that the pump isn't calibrated correctly. I'm no pro, but I believe my pump is advancing timing too soon or too fast. I should pull the pump and have it put on the stand to see if it's calibrated correctly. I've done some reading on the VE pump and they use a calibrated spring to offset the timing advance, which is controlled by pump housing pressure. Either my spring is broke, missing, or the wrong one maybe? No idea. It's a pain pulling a mountain with a trailer on the back and you can't go above 2200 RPM for fear of the noise.

Thanks for the reply GL.



Earl

 

[Greenleaf]

Hmmmmmm



You certain the noise isn't from something else? Transmission/Engine bottom end?



When did the problem/noise originate?



I performed some..... ahhhh... ... . pump "service" procedures on a VE that had no rear mounting cap screw and there was no vibration. Not to say that it could not cause a situation.



GL

 

[EZeis]

The noise is coming from left side of engine. I haven't tried running the engine up to the RPM till it makes this noise while under the hood yet. I'll try that tomorrow night at work and see if I can't find the vibration source that way.

The truck has done this since I bought it, about 1. 5 years. I know it's not rod or main knock. I know it's not flywheel/trans area. I know it's not valve train either. My guesses are the missing vacuum pump hardware (ordered), lift pump (OE with 307K), or I hate to think, cam/tappet area. But I doubt it's cam/tappet area, due to checking my valves three different times and they don't loose their spec. I've seen lift pumps on gasser engines wear badly on the lever that rides the cam lobe, so maybe that could be it? No idea. I'll have the vac pump hardware tomorrow and I'll run the engine up to speed while unloaded and under the hood to see if I can tell where it's coming from.



Earl

 

[BushWakr - RIP]

Your mileage is starting to suggest the following. . at least to me... .



It's starting to sound like pump problems... maybe Scott will confir on this idea... . at certain points in the RPM/load range the two heavy springs inside the VE that hold the cam plate and roller ring in contact can start to produce this sort of symptom (not the only thing) but what seems like your situation is the tight RPM range were you have the sound suggests that perhaps that spring(s) are starting to weaken or are near failure... ... . just a thought here... .



Another wild thought... . have you, by accident of course, put in any fuel conditioner that was designed for a gas engine??? I know, not likely but possible... .

Can you track this to anything you may have done (usual or not) when you first noticed this symptom???



pb...

 

[rlyons]

Mine has the exact same noise and it too is at 2200 RPM. Mine also has the diesel clatter all the way up the RPM range and yes I do feel it through the pedal. I just thought it was normal as mine has always did this. I've driven it for 5 years and pulled my 5th wheel all over the country so I guess it is not anything serious. I'm at about 185,000 now. I have tried advancing and retarding the timing, I have installed new injectors also. Nothing changes the noise or the RPM that I hear it so I just chaulked it up to the differences in motors or something like that.

 

[EZeis]

Pb,

Thanks for your input. I'm with you, I really think it's pump related. The pump was replaced 2. 5 to 3 years ago by the first owner. I'm the second owner of the truck and it's been doing this since I've owned it, which has been 1. 5 years. Either a spring is bad, broke, or the pump isn't calibrated correctly. It's all detonation noise. I'm guessing they can find problems with the pump on the test stand?? Truck runs great, more power then I need, doesn't use a drop of oil, never had any trouble. Just this detention noise has me worried. I just bought a 5th RV trailer that grosses at 10k and I would like to solve this before I blow pistons or such.

I noticed this when I test drove the truck before buying it, but I passed it off as worn injectors, but not the case. I think I'll get up early and go to the fuel system shop down the road and let them throw me some input.



Earl

 

[EZeis]

Rlyons,

Woohoo, someone know's my pain! :-laf I just don't think it's a normal thing though. Have you ever replaced your injection pump?



What for 5ther do you have? What does it weigh? Pull your 5ther over the Rockies? I'm planning a 30-day trip from PA to west coast and back a couple years from now. 2300 feet is about is high as it gets here in PA, so I'm wondering how my truck will do on those mountains out west pushing my 16K GCW.



Earl

 

[TKingsbury]

I've got some roughness that I can feel in my pedal as well. My engine also seems noisyer than it should be. Not severely, but not smooth either. Every now and again it will run as smooth as glass and just whiz on down the road like a gasser. I have not done any trouble shooting, just kinda ignoring it. Mine has had the pump replaced as well. The PO said it was done before he bought it. It only had 35K on it and was less than 3 yrs old when he got it. I figure it was a recall pump. I got it with 85K on it, so I figure it isn't worn out. I guess time will tell.

Travis. .

 

[mysteryman]

trouble at 2200 / compression test

I have one 93 5spd dually that does something like you All have described. .

It makes a detonation kind of noise around 2300 or so when I am running it hard goofing off... . I rarely hit 2100 most of the time but I still feel a vibration back threw the gas pedal during any acceleration most of the time. The truck is in mint condition and has never been beat. I did put new injectors in it and made sure that everything was adjusted properly.....

There was ONE Thing I DID find that I think is the cause of the problem. When I did a compression check I found that one cylinder was 50 + lbs higher than the rest... . This can be caused by only 2 things... . excessive carbon build up in one cylinder or a manufacturing defect in the combustion chamber or piston... I think it is most likely not a factory defect... ... One other thing it may be is an exhaust valve is not opening properly or fully but that is easy to check with a dial indicator... . Mine was fine.



In any event... ... one cylinder being higher compression will cause it to hit harder than the rest or better said it gives you an uneven power balance between cylinders..... Excessive compression will cause detonation... .

A dripping injector that is run for a while can cause excessive carbon build up in one cylinder..... Dripping injectors often are the cause of fuel being found in oil test reports... . I did find fuel in the oil in my report... . After new injectors it was not found in the follow up report... ...

Hmmmm????? Draw your own conclusions. I can't say that this is the cause of everyones problems in this thread... But I am hearing several of you that have the same symptoms as my white 93 truck has... . I have gone over that engine top to bottom just short of tearing the engine down. . I plan to do this in the spring. Its getting too cold now and won't be driving this one once the salt hits the streets until next spring... ...



I am willing to bet that when I pull the head I am going to find excess carbon in the high cylinder... . After that is corrected I am willing to bet that the problem goes away..... until then I can not draw any conclusions.....



I recommend that everyone that is having these symptoms mentioned in the thread do a compression test and write down the psi of each cylinder and see if one cylinder is 50 psi or more than the rest... .



You can make a compression tester easy enough if you do not have one.....

you can go to the welding supply store and buy a torch gauge that reads up to 750 or so and use a gutted old injector body... . you will also need to put a one way valve in the line some where. An old tire valve core works well for this.



Before you start REMOVE THE BLUE WIRE FROM THE INJECTION PUMP.

We do not need to be spraying fuel all over the place while doing the test.



Doing the test you need to remove ALL the injectors before you start... .

You do NOT need to remove the lines from the injection pump but you DO need to remove ALL of the clamps that hold the lines in place... . Removing the valve covers also helps make for more room to GENTLY move the lines to the side to pop the injectors out... If they stick and will not come up. It is because there is carbon buildup on the tips... . To free a stuck injector you can make a tool to remove them by taking a very SMALL dent puller (3/8's diameter shaft) and attaching a fitting to the end of it that fits the injector line thread... Such a cheapo dent puller can be picked up at wal mart or a harbor freight store. Be gentle a make sure you spray and blow off the tool's fitting thread ... . No metal chips can be allowed to go down inside the injectors.

Screw the tool on the injector and gently tap... . It should come out fairly easy using the tool... . The rest is self explanatory... buy and or read your factory service manual ... Follow the torque spec's ... . And do not buy a cheap torque wrench!!! Utica/Bonney was the big name in torque wrenches for most of my life time. . You can pick them up cheap on ebay..... Sears ,harbor freight,advance auto parts ect sell JUNK torque wrenches... I bought several of them and have found that they are way out of spec !!!!



I also Highly recommend that before you start that you buy a few cans of Gunk engine brite and a scrub brush and clean the top side of the engine... We do not need any grit falling inside the injector bores...



I realize that some of you are pro's and or well versed with the above.....

I am not talking down to any of you... I post the above for the benefit of those that may not have ever done this before and or those that want to save some money on special tools... ... .



The problem in question is a real mystery..... I have yet to find anyone that has had a good explanation for it..... Not from several of the cummins dealers nor from any of the engineers at cummins..... I will figure it out sooner or later... . with some of your help it might be sooner... . I think we are going to find that it is the same thing that causing the problem on all the trucks in question... . I think that it has not been addressed yet because the trucks are just now getting old enough to start having the trouble in any number...



Please do post what you have for compression psi on this thread... ... .

I really do want to get to the bottom of this one! It has been bugging me to death for a year.....

Pb,

Thanks for your input. I'm with you, I really think it's pump related. The pump was replaced 2. 5 to 3 years ago by the first owner. I'm the second owner of the truck and it's been doing this since I've owned it, which has been 1. 5 years. Either a spring is bad, broke, or the pump isn't calibrated correctly. It's all detonation noise. I'm guessing they can find problems with the pump on the test stand?? Truck runs great, more power then I need, doesn't use a drop of oil, never had any trouble. Just this detention noise has me worried. I just bought a 5th RV trailer that grosses at 10k and I would like to solve this before I blow pistons or such.

I noticed this when I test drove the truck before buying it, but I passed it off as worn injectors, but not the case. I think I'll get up early and go to the fuel system shop down the road and let them throw me some input.



Earl

 

[JLEONARD]

Please do post what you have for compression psi on this thread... ... .

Would it be worth it to make up a compression testing "kit" and have it available for those who want to do the test?



I would donate my home made injector puller and maybe some fittings, but I don't have a spare injector body or a gage. . it will need to be able to handle what. . about 450 psi or so?



Also should nail down a proceedure... I've seen diesel compression tests done while cranking, and while running on 5.



thoughts?

 

[Greenleaf]

I have plenty of spare injectors.



-S

 

[rlyons]

EZeis, No I haven't replaced my pump yet. My 5th wheel is only about 10K loaded but pulled it through the mountians of New Mexico with no problem at all, in fact I never got below 4th gear except on a couple of very steep grades. I did wish for an exhaust brake and will get one sooner or later. I don't think you will have any trouble at all as long as you keep the rpm up.

 

[TKingsbury]

Like I said, mine will go away sometimes. I don't know what's up. I did give my crank end-play a quicky look today, and it hardly twitched. It moved just enough to feel it. My truck led a very easy life with the PO. I have noticed that when I take a trip with a load on it, the more and harder I run it the better (happier?) it is. I dunno.

Travis. .

 

[rlyons]

Mine is exactly the same, with the trailer it runs quieter and better than empty. Some days it is smooth and quiet and some days it is very noisey. When I was in New Mexico it ran it's best and was very smooth and quiet. The exhaust smelled strange so I assumed it was the fuel. I do know that these trucks do not like wet or hot weather. Mine runs great when it is cool and dry. These trucks seem to thrive on heavy load and high boost.

 

[EZeis]

Rlyons,

Thanks for the info. Dealer is prepping my trailer, so I haven't hauled it yet. My old ball trailer was 7k, so will be fun to see how it pulls the new trailer.



Earl

 

[EZeis]

Carbon is something I didn't think about. Could be my problem. When I removed the old injectors, they were heavy with carbon. Also when I started using Lucas fuel treatment, it cut the detonation noise by half. Maybe it burnt off the easy carbon and won't cut the harder stuff. The milage, the noise, and wanting a bit more power, I figured it was injectors since the Lucas cut the noise by half. But new injectors only gave me more power. :-laf



Next question is, how can one remove carbon without removing head? Any kind of fuel treatment that does well for carbon? Lucas did wonders, but must not be strong enough.



Can carbon build up be harmful to my engine???



Earl

 

[mysteryman]

My noise seems to come and go also. . I think it depends on the grade ,load and where I bought the fuel from... .

Like I said, mine will go away sometimes. I don't know what's up. I did give my crank end-play a quicky look today, and it hardly twitched. It moved just enough to feel it. My truck led a very easy life with the PO. I have noticed that when I take a trip with a load on it, the more and harder I run it the better (happier?) it is. I dunno.

Travis. .

 

[BushWakr - RIP]

My experience is similar to Mysterman's... . it will come/go depending on fuel grade, speed RPM etc... . it's certainly worse in winter with the winter grade fuel.

I think you should use a real heavy dose of injector cleaner including some cetane improver in the next tank of fuel.

I'd suggest (I have done this) using double dosage recommended and then take the truck out an work it hard... get it hot, vary your speed and throttle and so forth.

You could then add a general fuel treatment after you go thru the tank with the cleaner.

If necessary repeat the process. You should have pretty much cleaned out the fuel system once you've done this. After that, you're likely just hearing injector noise which is often audible.



pb... .