E7 mack mechanical injection pump will only idle

[Rock dump mack]

1996 mack e7 250 with mechanical Bosch pump that has fuel turned up was running ok at highway speed and suddenly went to idle. Checked all linkages seems linkage on side of pump is barely moving any ideas or suggestions before pulling the top off of pump seems to have good fuel pressure and volume 

[Joey Mack]

is the throttle link slipping on the throttle shaft?   if so, you can pull the 'D' shaped spacer out of the arm to get it tight untill you get a new arm link..  just be carefull that you dont damage the shaft..jojo

[theakerstwo]

If it will still idle and idle with out any missing then it may have a stuck rack.But do as JOJO said and make sure your linkage is ok and the lever is ok.And to make sure you have fuel pressure you need a gauge on it.If the pressure has dropped enough to cut the rpm back it would be cutting out and not idling good.Last check is pull top off of governor with engine dead watch the rack and pull the stop to kill and then release it to the run position and then push the fuel lever in full fuel position and watch the rack move in and out.

[Joey Mack]

I was hoping you would show up on this one Glenn....  jojo

[theakerstwo]

And if your rack will not move then pump needs to go to pump shop.Then look in the bottom of fuel tanks for water.