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Surging/ accelerating while at an idle??

Nosferatu49534

Nosferatu49534

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Grand rapids
Whole sitting here waiting for my wife to get out of work my truck has accelerated, almost like goosing the throttle. It doesn't go crazy just a few hundred rpm or so. Any thoughts?
 
I haven't noticed any in the clear return line other than when I shut the truck off there is a small spot at the top of the bend that doesn't have fuel in it.
 
A bad PMD or a bad IP can have a full throttle event, usually in a bad spot. So I've read.
 
With the pmd it's pretty much a replace and see if it works right? How do I check the injection pump? I have receipt a of the injection pump being replaced in 09' at 200,000mi. Says it was a gm reman.
 
Yes, replace with known good is only diagnosis. That's part of why I say you must always carry a spare good one. The fact that in can go from perfect to toast in 1/2 second is the other. Murphy's law says most deserted place, dark rainy night, when your in a panic to get home. I h8 Murphy btw, he used to just make soap till he met me;)

When I worked on fleets, we had a few just go full throttle for no reason. 1 w/ me driving. I'm convinced it unloads a couple of ponies more than just full throttle when it does it too. Scared me bad enough that I will not own another ds4 truck. Oil company I worked for had to dish out a couple million when the driver of 1 lost control and killed a gal. Anyways, sometimes no warning, others acted like you describe first- which is why I was test driving it. You think shut met off and it instantly dies? NO! Took about 5 seconds to die. I turned of key, slipped in neutral, and watched tach scream at 4400ish rpm for a few seconds. I popped the hood took of my shirt to stuff in the intake to choke it. Seriously thought I was having oil burn run away.

Just be careful, stay 1 car length farther back at stop signs, and more space in moving traffic.
 
With the IP check, try to slowly raise rpm to 2000 then slowly drop to an idle. A good IP will do it, a bad one will not.
 
Gotcha. Murphy is jerk for sure. I'll have to order a new one. If nothing else I'll have a good one then. I know Leroy has them, and I feel like he mentioned something in another thread that the flight systems one was actually the better to get?
 
NVW said:
With the IP check, try to slowly raise rpm to 2000 then slowly drop to an idle. A good IP will do it, a bad one will not.
Click to expand...
ak diesel driver said:
To add yo what Leo said it should stay nice and smooth and steady as you go up and down in RPM.
Click to expand...

And each cycle (at least 10 of them) should remain consistent with the other. Also, hold the throttle at 2,000 RPM's for a few seconds prior to coming back down. Any deviation from cycle-to-cycle, or RPM run-away (will not hold at 2K), points to an IP replacement.
 
I've got plans after work now. Hopefully it's just the pmd. Or grounds. I still have a couple to clean/ replace. Thanks guys.
 
If it is the IP, my vote is pay the $$$ for new. To my knowledge, Stanadyne is still the only OE supplier. Also, make sure it is rated for ULSD (but still add some lube for the injectors anyway).

Unique Diesel and Constenoga (sp?) have reputations for modifying the IP, but if the rest of the motor and cooling stack are not ready for more fuel, probably best to stick with the Stanadyne.
 
Ok. At the most for upgrades I really only plan on the att at this point any way. I just want a good running truck as I don't pull more than maby 1 vehicle a yr or so.
 
I decided before I get to excited I went through the grounds on the passenger side. Made 2/0 cable from cab to frame, and frame to intake. Used kopr kote on all the connections. Not a lot but enough the a small amount squeezed out the sides as I tightened. Still started kinda hard this morning but the volt gauge in the dash stayed constantly just over 14 volts. Only fluctuation is when the glow plugs turn on and off for the after glow. Seemed to run better, and a little more power. I'll keep updating as I figure things out.
 
Will said it best, but, X2 on just replace the PMD, NOW! Some were known to go bad and run away. They changed the later design to help prevent that. I also recall one brand had a defect in a production run or design that allowed runaway.
 
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