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Cummins Diesel Tech?


Whitey741

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A Lot of smart guys around here so and a couple diesel techs if memory serves me right. Please help if you can.

 

I have an '05 3500 Cummins and all of a sudden today it started surging/ accelerating as I leave a stop before I even touch the throttle. Also when stopped It seems as if it is trying to compensate for something while idling in gear by raising the idle speed. (I understand this wouldnt necessarily be a surge but not exactly sure how to describe this.) If I shift into neutral from drive or reverse it runs up to 1500-2000 or so before returning to a normal idle. I had just filled up with fuel 30 miles earlier so I drained a bit into a bottle to see if there was anything unusual. Seems OK but almost too coincidental. I did see a few drops of water (1/8" diameter circle combined) in 32ozs of fuel after a couple hours settling so I added fuel dryer to see if this would help. Could it be bad fuel and the cpu is trying to keep it running by raising the idle?

Thanks in advance!

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The idle speed is computer controlled - you will need to get it scanned to see what codes are there.

 

NEVER use fuel dryer in a diesel! Even a small amount of water can ruin your injectors. Diesel fuel systems are designed to separate our the water, you should have some kind of "water in fuel" indicator (I assume this is standard for all diesels, my Ford has it) and a way to drain the trap. Fuel dryer is nothing but methanol which allows the water to mix with the fuel..

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Thanks 1 crew,

It was CRC Diesel Dry (12 ozs in 35+ gallons of fuel) "Contains no Alcohol" according to the label, just Petroleum Distillate, Stoddard solvent, Butoxyethanol, and one more really long one I'm not gonna type, Unless the butoxyethonal is an alcohol (sure sounds like it) Not sure how it would work with no Alcohol. Figured it wouldn't do much but didn't think it would hurt either. Seems more like an injector cleaner when reading the label than a fuel dryer. I did drain the "trap" that is where the water described came from. Equivalent to one rain drop in a quart of fuel after settling for 6+ hours now. .That drain hasn't been opened in 3 months.

 

I sure hope I didn't mess this up!

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Curious if you have a chip or programmer? David(BlueMoonMotorsports) had his chip go bad and it went WOT on him several times. David can tell you better as to how they came to realize it was the chip. I know he said they did several things including I believe pulling the harness(main) on the truck.

 

Mark

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IVE SEEN A FEW OF THESE DOES THE UNIT HOLD UP ON HIGH IDLE FOR A WHILE THEN GO BACK DOWN SLOWLY THE 2 I HAVE SEEN OR WORKED ON THAT DID THIS U COULD NOT PULL CODES AND THE ECU HAD AN INTERNAL FAILURE THE ECU IS COVERED UNDER EMISSIONS MOST THE TIME SO IT SHOULD HAVE A VERY LENGTHY WARRANTY GOOD LUCK ;)

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I think everyone is on the right track when they tell you to take it in and have it hooked up to a diagnostic computer. Not real sure on a Dodge, but on a Chevrolet surging can be one of the first signs of a fuel pressure regulator starting to act up. Unfortunatly that is a symptom for several different things.

As far as trying to "dry the diesel" I wouldn't recommend anything other than Stanadyne. It's really a catch 22. You REALLY don't want any water in your injectors; however, most anything that you mix with the fuel to remove the water will cause your seals to go bad which will also lead to injector failure.

Hope that helps. If you would... let me know what you find out.

Thanks

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Thanks everyone for all the help.

 

Turned out not to be a fuel problem at all. The torque converter was locking up. It definitely seemed different than a lean surge.

 

This does raise another question though. Will one bottle of that stuff ruin pump seals? I sure hope not. This truck has been great so far. 104,000 and haven't even had to change the oil...........

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