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Discussion Starter · #1 ·
We have a NHC-250 Cummins and when I drove it around the yerd last night whenever I mashed the go pedal it was very sluggish to rev up and when I let off it took a long time to slow down to an idle. Its never done this before. It's not in the linkage because all it has is a rod from the pedal about 6 inches long. It's a 1970 and its in a Dodge CNT-900. Any help is much appreciated. Dave
 

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Discussion Starter · #3 ·
Its getting fuel because once you get it reved up it runs like normal but its just slow revving up and slow to slow down to and idle
 

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Are the fuel filters plugged? That would cause slow rev up. Check you fuel tank vent as well. I have seen tanks with clogged vents that pressurized themselves from hot return fuel push fuel pat the PT pump and increase the idle and/or make them defuel slowly, etc.

What model pump is on it? Has anything been done to the pump?
 

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Discussion Starter · #5 ·
not sure about the pump model, but it is all stock, I'll check the tanks, i haveent found the vents but i know I always had to tighten up the lids, maybe i tightend them up and caused this. I'll get back on thursday night because I stay at my grandpa's every other night and he don't have a computer. Thanks
 

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you might want to check the fuel shutoff solenoid on the top of the pump.if my memory serves me correct,screw the screw in to put the pump in manual mode,will not shut off with the key.the solenoid might be going bad,or the power wire might just be loosing contact.
 

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I believe you are correct, not sure without looking at it, but if you screw the manual screw in it'll turn the fuel on. With the screw out the valve is in the no fuel position, which is why losing key power at the solenoid will shut the truck off going down the road.
 

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Discussion Starter · #9 ·
I checked the tanks and no pressure/vaccume on them at all. So I decided to take it to the back of the farm and back and it had all the power it usually had. It also seemed to run fine exept when you let off the fuel it would idle down fine but once it hit the bottom it would go down a bit more then rev back to normal. Its not enough to worry about but I dont recall it ever doin this before. thanks for all the help.
Dave
 

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A slight idle dip is not totally uncommon and unless it's dip far enough that it has a hard time recovering I wouldn't get overly excited about it.

If it becomes more of a problem, or the truck doesn't have the power it should then I'd tare into the pump and adj/overhaul it and make it work like new again.
 

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Discussion Starter · #11 ·
thanks, sorrl im late to respond, i was on vaccation for the week
 

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I just purchased this 2010 M931A1 5 ton truck 6x6 with a NHC250 Cummins. It had issues starting and hard time to keep it running. I replaced the fuel filter and bleed ****s got it to start and now it wants to over rev above 4.5k rpm. had to shut it off. It does it every time starting it up. what areas to I need to look into? seems to want to be a run away diesel. what can I do? Not sure what's going on with it. please help...
 
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