loping at idle

[nathan79]

I have a 99 cummins that lopes at idle whenever I stop and push the clutch in. It does this for 20-30 seconds then smooths out to just a rough idle. It has a lack of power and runs a little rough at highway speeds. It has 188,000 miles on stock everything except a fass fuel pump and filter system installed 400 miles ago. Any idea on the problem? Thaks for your help in advance.

 

[marblecrusher]

Do you have gauges? (fuel pressure, boost, and egt) If so what is fuel pressure at idle and WOT? Which FASS system was installed? Also have you checked for codes?

-Jordan-

 

[tate228]

I would make sure your fuel pump and filter are set up correctly. really sounds like starving for fuel.

 

[wmoguy]

Have you checked for codes? My 01 did that same thing right when it was vp44 time. Check your codes on the dash.

 

[marblecrusher]

The key trick only works on the 01-02's he'll have to get a scanner for the 99.

-Jordan-