Idle surge - dangerous!! What is going on?

[DmaxCC6spd]

My 6.5 will on occasion have a sudden surge in the idle speed. So far it hasn't rolled me into the back of another vehicle! I can see the RPM jump up to about 1000 RPM. Generally it will do this twice in very quick succession. Any ideas to check? 94 6.5TD and about 203K miles. I'm the second owner so I'm not sure what has been done as far as major maintenance. Any thoughts? This is concerning and somewhat dangerous. I won't let my boy drive it like this. You have to be on your toes - or more specifically the brake!!

TIA

[JohnC]

Could be a flaky Fuel Solenoid Driver. Scan it for codes; sometimes they leave evidence behind. Also, if you have a real time scanner, monitor the fuel solenoid closure time (IIRC- it's been over 15 years...)

[DmaxCC6spd]

Is the Fuel Solenoid driver different than the PMD? I have no check engine light, but I'll check for codes.

[JohnC]

Is the Fuel Solenoid driver different than the PMD?
No, same thing, but if it's not mounted on the pump than it doesn't make sense to call it a PMD...

[DmaxCC6spd]

Found the following on this site: https://www.accuratediesel.com/pmd_list.html

If your truck over-responds to the throttle and revs up very rapidly at only light throttle application, or revs up on its own, internal injection pump wear is almost certainly the cause.


I really don't want to change a pump. Way too busy for that.