6.9 idi keeps stalling while shifting gears
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Joined: Jun 2019
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6.9 idi keeps stalling while shifting gears
I have 86 f250 6.9idi 4 speed with duel fuel tanks. Another day I took my truck to go get groceries and when I left my driveway on to the street, the moment I shift gear 1 to gear 2 with me putting in the clutch, the rpm drop to 0 and stalled. I freak out and release the clutch and it jump started it self. I turned around went back home. The next I turn on the truck and turn on with no hesitation. It only stalls when it's coming down from high Rpms. Is bad fuel lines or Injectors pump? Please help. I appreciate it.
Posting Guru
Joined: May 2015
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Sticky/stretched governor slack spring would be my guess.
You can try pulling the fuel filter, filling with either diesel klean or atf and start and let it run for 30 seconds and then shut off and let it sit over night.
Or on the back of your pump there is a stud coming straight out that takes a torx bit and has a hex jam nut. You can loosen that nut and walk the stud in 1/4 of a turn at a time until you get it where it stops dying. It will affect your idle so you may have to turn it down on the screw on the side of the pump afterwards. should notice better pedal response once it's adjusted correctly as well.
There was a technical service bulletin for this problem back in the day.
You can try pulling the fuel filter, filling with either diesel klean or atf and start and let it run for 30 seconds and then shut off and let it sit over night.
Or on the back of your pump there is a stud coming straight out that takes a torx bit and has a hex jam nut. You can loosen that nut and walk the stud in 1/4 of a turn at a time until you get it where it stops dying. It will affect your idle so you may have to turn it down on the screw on the side of the pump afterwards. should notice better pedal response once it's adjusted correctly as well.
There was a technical service bulletin for this problem back in the day.
More Turbo
Joined: Oct 2014
Posts: 697
Likes: 82
From: Alberta Eh
Mine did the same thing a few years ago. It will start and run fine but when you take your foot off the throttle it dies. Even when you blip the throttle it will idle down below its base idle, catch itself n then come up to its base idle. Iirc there is some kind of plastic ring for the governor (?) or something that fails and causes those symptoms because it restricts fuel flow at low rpm. I replaced my IP and that solved it. You could try the atf in the fuel filter treatment overnight just to try all options before spending the $$ on a new IP. Somebody will be along to offer more advice before we are set on the IP being the cause for sure
More Turbo
Joined: Oct 2014
Posts: 697
Likes: 82
From: Alberta Eh
Mine did the same thing a few years ago. It will start and run fine but when you take your foot off the throttle it dies. Even when you blip the throttle it will idle down below its base idle, catch itself n then come up to its base idle. Iirc there is some kind of plastic ring for the governor (?) or something that fails and causes those symptoms because it restricts fuel flow at low rpm. I replaced my IP and that solved it. You could try the atf in the fuel filter treatment overnight just to try all options before spending the $$ on a new IP. Somebody will be along to offer more advice before we are set on the IP being the cause for sure
Scope Wizard
Joined: May 2019
Posts: 6,530
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lot of the early pumps had that rubber/plastic Flex ring that held the governor weights, think most now have the stainless flex plate... you can pull the return fuel check valve and inspect it for pieces of the flex ring as that is where some of it usually ends up.
I would also verify the return lines are clear and check lift pump pressure too, you could have some bad fuel too so checking the filter is a good idea too
that Return Line check Valve is the Housing Pressure regulator, keeps the pressure around 3 PSI IIRC and if it plugs then the Pump quits as the housing pressure gets too high.
I would also verify the return lines are clear and check lift pump pressure too, you could have some bad fuel too so checking the filter is a good idea too
that Return Line check Valve is the Housing Pressure regulator, keeps the pressure around 3 PSI IIRC and if it plugs then the Pump quits as the housing pressure gets too high.
Postmaster
Joined: Dec 2011
Posts: 3,860
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I ended up just screwing in the "guide stud" at the back of the pump which adjusts the min/max levels, and also the "pickup". That got it back to 'not dying' when letting off the throttle.
When the alternative is "replace the IP", what's the risk?
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Logistics Pro
Joined: Sep 2007
Posts: 3,737
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From: Western Mass
I had that same issue with my pickup, hit the clutch and it could stall out. When not in gear if I goosed the pedal then took my foot off, when it came down in revs it kept going to zero and stall.
Filled the filter with ATF ran it for a minute to get the ATF into the injection pump and shut it off. I let it sit an entire day and it cleared up. That was maybe 4-5 years ago, soon after I had gotten the truck and it had been sitting for a while, and I didn't use it much for about 2 years after I got it. Ever since its been used more frequently and never had the problem again.
Its a cheap fix so I'd try the ATF or diesel-kleen or whatever you like to use to un-gum whatever it is that sticks up in the pump.
Filled the filter with ATF ran it for a minute to get the ATF into the injection pump and shut it off. I let it sit an entire day and it cleared up. That was maybe 4-5 years ago, soon after I had gotten the truck and it had been sitting for a while, and I didn't use it much for about 2 years after I got it. Ever since its been used more frequently and never had the problem again.
Its a cheap fix so I'd try the ATF or diesel-kleen or whatever you like to use to un-gum whatever it is that sticks up in the pump.
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Lead Driver
Joined: Apr 2008
Posts: 6,940
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Just seconding whats already been said. Ive fixed two of my pumps (doing the same thing) by letting them soak in some atf. Dumping a quart or two in the tank wont hurt anything either. Would do non synthetic btw.
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