Idle problem on 6.9

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Mar 21, 2011 | 01:09 AM

dreamison

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Idle problem on 6.9

Hey, I have had my new to me 6.9 for about two weeks now and the idle is very inconsistent on it. When it is cold it will idle high at 1100 rpm and then kick down to about 650-700 when it gets warmd up which is normal. But after about a half hour of running the idle will dip down in the 400 range and act like it wants to stall. If run it up it will stabilize back to 650 again. It seem like it is happening intermittently. Other wise it runs good. Is there some adjustment or solenoid that controls idle. Its almost acting like a sticky iac would act on a gas engine.

Mar 21, 2011 | 08:52 AM

84-6.9L

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From: Princeton MN

First check and make sure the linkage on the pump is contacting thr stop on the pump and isn't bent. Next try the "Diesel Kleen fix" spin the filter off, fill it full of diesel kleen, dump the rest in the tank, bleed the filter, then run it for 15sec shut it off and leave it sit overnight. It doesnt sound like air intrustion because it doesnt surge and you said it comes out of it when you manually bring the idle up. Does it stay up then if you let off the pedal? Are you currently running any additives? How old is the pump and injectors? Are your return lines replaced or are they still painted gray? How many miles on it?

Mar 21, 2011 | 10:50 AM

dreamison

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Yea it will stay up when i let off the pedal. I just have to give it a quick bump and it will recover. I am the third owner of the truck and the girl I bought it from swears that the mileage is true at 76k. She said that she bought it from the original owner and he just used it in the summers for fishing and camping. But I cant be sure how many miles are on it. The injector lines and injectors still have factory paint, not sure about the ip, hard to tell. But it runs out great no smoke, except for on cold starts a little puff will come if I have to crank it for a few seconds. I'm still waiting for my new gp's to get here. No leaks anywhere around the Ip or injectors, it looks like there are newer return lines on it and it all dry and clean.

Mar 21, 2011 | 11:24 AM

84-6.9L

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From: Princeton MN

If its that old with only 76k on it something tells me its had some old fuel run though it, get a new fuel filter and try the diesel kleen its what god would run if he had a diesel, great stuff and has many documented mericles.

Mar 21, 2011 | 11:51 AM

dreamison

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Yea, thats first on my list today. I have the filter, just need to grab some diesel clean. I've ran two full tanks of fresh diesel through it since I got it. I was also thinking that maybe the lift pump is weak because its happening after I run it for awhile.

Mar 21, 2011 | 10:38 PM

BlueOvalBud

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From: Massachusetts

On my old pump, it would idle great. But it you punch the throttle and let off, it would drop down LOW and sometimes stall. A quart of ATF in the fuel filter did the trick for me.

P.S. .....please say those glow plugs you've got coming are Motorcraft/Beru brand....

If not, return them, and buy Motorcraft/Beru plugs.

Mar 22, 2011 | 01:11 AM

dreamison

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Yea I've got diesel kleen sitting in it overnight tonight. I just bought the truck less than two weeks ago and the PO said she put new gp's in it as part of getting ready to sell it. When I went to look at it, the glow plug light was cycling off after less than 2 sec and the relay was clicking. It had a new set of autolite plugs in it and 5 of 8 are already bad at less than a month old. I do have motocraft AD9 plugs on the way.