IDI Surge
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Senior User
Joined: May 2013
Posts: 286
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From: Salem, OR
IDI Surge
In the last couple days my 86 6.9 N/A has started to surge at about 40/50 mph. It seems to have a flat spot like its running out of fuel, then after a few seconds it will surge fwd (as much as an IDI will surge). It seems to be getting worse lately. I have no visible fuel leaks, so am assuming it could be any place between the tank and injectors.
All suggestions are appreciated.
Also does anyone have experience w/a Donaldson 4" x 40" lg muffler #M085421? I'm going to replace the stock exhaust taking it out the back. I am not sure what would be the best muffled to keep it reasonably quiet yet reduce back pressure. I've read some about diesel drone, don't know if that's a turbo issue or effects all diesels, but I want to be able to carry on a conversation in the truck.
Thanks
All suggestions are appreciated.
Also does anyone have experience w/a Donaldson 4" x 40" lg muffler #M085421? I'm going to replace the stock exhaust taking it out the back. I am not sure what would be the best muffled to keep it reasonably quiet yet reduce back pressure. I've read some about diesel drone, don't know if that's a turbo issue or effects all diesels, but I want to be able to carry on a conversation in the truck.
Thanks
Senior User
Joined: Jul 2010
Posts: 170
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From: Western SD
Changed the tach sensor and everything went away.
Postmaster
Joined: Dec 2004
Posts: 2,941
Likes: 30
From: Maple Valley, WA
Sounds like an advance piston issue in the pump...
Early on in the DB4 stuff, the bigger cam pin caused light load advance issues like your saying, and it was due to the change in dimension of the trim piston... It would pulsate at around 50-60mph...
If you have no fuel system leaks, Id look at your IP for a worn advance piston assy...
Early on in the DB4 stuff, the bigger cam pin caused light load advance issues like your saying, and it was due to the change in dimension of the trim piston... It would pulsate at around 50-60mph...
If you have no fuel system leaks, Id look at your IP for a worn advance piston assy...
Freshman User
Joined: Jul 2013
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my truck does the same thing when it gets just below half a tank on either the front or the rear. 90 350 7.3
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Joined: Jun 2007
Posts: 2
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From: Orangevale
My'93 F350 does the same thing right at a quarter tank on the front tank and now the rear tank. When I first got the truck I dropped the tank and it was a cracked pick up disc on the sending unit. Added a small piece of fuel line and now goes till its almost empty. Didn't get the right part because when I called around the parts places told me their was a few different styles used by Ford. Didn't have to drop tank completely, just got it tipped and could weasel the sender out. Going to do it right someday.
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