Umm - fuel filter clogged? bad fuel?
 

Hi guys,

Well, I only have 11000 miles on my 2007 5.9 - automatic. Here is what it did over the weekend. I put 16 oz of power series in it (it had a 1/2 tank in it) before driving it the 2 miles to the gas station and topping it off. Now it does this... idles a little rough, and while at low rpms usually after an upshift while not giving much gas, it studders - kind of badly as if it is missing or needing Fuel. I am on the original fuel filter. I have run it through about a 1/2 tank and it is still behaving this way. My hope is that this is the classic fuel filer getting clogged symptoms and not indicative of something worse like an injector. Would it be normal to get hold of some bad diesel every now and then to cause this? Normal to have it clog by 11000 miles?
Too much additive? (maybe I had added it to the previous tank as well and forgot since I am not really regular about the additive). Would not be worried it my power steering pump had not gone in 6000 miles but now I analyze everything.

I'm no expert, but if it were mine I'd change out the fuel filter and see what happens...

From what I remember that is too much additive. The new change interval of the 7 micron Fleetguard filters is 10,000 miles so you are over 1,000 miles. I change mine every 10,000 miles anyway.

Cummins says on their site that the oil change intervals are 15K and you need to replace the fuel filter when you change the oil.

Although, I waited till 15K for the fuel filter between 10-15K miles sometimes I'd get some slightly rough idle when sitting at a light or whatever. So I guess you should probably try that IMO or take it to the dealer and tell them what it's doing.

I might start doing 10K fuel filter and oil changes to simplify things.

Depends on where you live. Lot of areas that throw alot of dirt and dust around. I'd change it and go from there. At least you could ease yourself knowing you changed it. And I usually put my additive in at the pump before or after fueling, whichever one comes around.

Power Service says to add at ratio of 8oz per 40 gallons.

I had same problem and eventually got code 'misfire on cylinder2'.

Took it to dealer and they showed no codes or trouble.

I used to add PS and 2 stroke every fillup, I stopped because of this problem.

I havent added anything in 4 months and it seems fine.

If I let it idle for more than 10 minutes I feel it get rough again.

I started 'getting on it' at least once a day to blow the crap out.

Thread on this site says daily drivers rarely get above 20% engine load and that may cause these symptoms. (too much lo range rpm driving)

Fuel filters are $15 at Genos and take 5 mins to change, I'm trying to do mine every 8K miles...I mean, why not?

Additive
 

Well, as far as the additive calculation goes, I figured that I was probably ok and the additive did not cause the problem. Here is my logic. 1 gallon of PS says that it treats up to 300 gallons. Since a gallon is 128 Oz, that comes to about 14.5 ounces per full tank (34 gallons). I figured since I did not have additive in it currently (may have screwed that up) that 16 ounces per the whole tank was pretty good. Funny thing was, I let it warm up a while before driving to the gas station with the 16 ounces in only a 1/2 tank and it was running good when I got there. 20 miles later, no good. Could be coincidence that the filter clogged then , could have been bad gas, I am just really hoping that the symptoms match up to what a clogged filter would do. At higher RPMs, like crusing down the road at 70, no problems. If it was studdering/surging and I gave it more gas to downshift and accelerate, no problem either. Was still doing it at the end of a 2 1/2 hour trip (of course most was crusing at 70 with no problem). Loud sound like valve lash/lound knocking also at the lower RPM's. Thanks for the replies.

I think I figured it out......[dummy]

Ha Ha
 

HA HA,

I meant bad DIESEL FUEL!


[laugh]

Yeah, I'd just get that filter swapped out and see whats up. One thing I would suggest is you consider getting some gauges or a monitor. You'll be much more informed as to what is going on with your Cummins, at a glance.

Correction
 

PS comes in a 96 oz bottle and not 128 (gallon). Therefore, it should have only been about 10 ounces per full tank. I gave it about 16... and if I accidentally forgot I had done that to the previous tank,which was half full, well, I overused it (dont think I did that but I am forgetful lately). Maybe that brought the detergent level up to where I scrubbed some crap out of my fuel tank and plugged the fuel filter. Who knows... Ill top it off with fresh fuel and its about time for the fuel filter and oil anyway so Ill do it when I have some daylight.

FYI, Power Service in the big bottles are only hold 96 oz. IIRC you only need to use 9.6 oz per tank.

JM02

Update
 

Well, just to help others who may search threads later for a similar issue ...here is how this turned out. First, I did nothing but change the fuel filter. That appeared to be what fixed it and I noticed some power difference as well. Those of us who have not been towing very often may have a clogged filter sneak up on us easier I would guess. After that, I changed the oil and have to say that the Rotella T "synthetic" 5w-40 feels really good in the truck...planning on using it at least in the winter. Would have completed the grease job too but did not have a needle adapter (would have been nice to note that in the service manual). I am not exactly sure how to tell when I am done greasing it as some think you should grease till it blows out and others disagree. Thanks for the comments.

Since fuel filters are essentially inexpensive, and the time to change them is minimal, I just change my fuel filter with every oil change. In fact, while my oil is draining out I do the fuel filter, so the time is wrapped up in the oil change. I noticed that I would also see a slight fuel mileage decrease at about the same time I was due for an oil change, so that is what made me start changing out the fuel filter at the same time. My mileage woul go right back up to where it had been.

I also clean the air filter at the same time and grease the truck. Since I have a bypass filter, I change it every other oil change.

Yes, it would have been nice if they had stated the need for the needle adapter in the manual, but probably their thinking was that you would have been doing your ervicing at a dealership and the service guy woul have had one. As far as greasing until the grease blows out, I have never been one to do that because the object of the rubber is to seal out dirt, when it allows seepage of grease out, it then allows dirt in, defeats the purpose of it's protection aspect in sealing it off in the groove. I look for a little expansion of the rubber cup and call it quits, give places without the cup a couple pumps of grease.

CD

Update - Dealer is replacing my PCM
 

Well,

the symptoms returned after about 600-700 miles on the new fuel filter. Took it to a dealer. Dealer say that the PCM needs to be replaced and that the fuel filter needs to be replaced. Hmmm, dont know about the PCM affecting the fuel filter...thought lift pump ran all the time anyway. Hoping that they just always suggest that to be sure and that they have a clue (not that I can say much cause I am no mechanic). Anyway, I was expecting an injector issue .If they think the fuel filter is clogged I would suspect bad fuel and would have taken a fuel pressure measurement at a couple spots is possible. Anyway, I told them the fuel filter had jsut been replaced and told them they could use my stratopore that is kept behind the back seat if they needed a better fuel filter than the one they are no doubt going to charge me 40 bucks for.... ;)

Anyway, they said the PCM was not making rational decisions on air/fuel given the parameters it was receiving and therefore they were replacing it..... ITs under warranty (12000 miles about) so I am not complaining but I still am just a little bit skeptical....