E6 350 injection pump

[elm]

Hello, I assume this topic has been discussed before, but ether I'm an idiot (most likely case) or my search isn't working and I cant find it.  So if I'm repeating an old question, please point me to the right spot.   

I've got a E6 350 manufactured 10/91 and its doing the lopey idle thing and is a little hard to drive smooth because it lopes a little any time your holding a steady speed.   Its got a Ambac pump #GMS450 206.  I've read somewhere its a common problem and most likely the bushings or springs in the throttle governor.  I've also read that's its very easy to fix and that its very hard, so I'm not sure what to believe.   but the worse part is, I cant find any info on the Ambac pumps.  almost like they never existed.   I don't want to pull it apart until I can get a bit more info somehow.  anyone have more info on this topic?

[Joseph Cummings]

That number doesn't sound right. Do you have a picture of this pump?

[elm]

I cant get the picture to upload (always says a server error accrued) but the number is crystal clear on a blue tag that says AMBAC.  the tag is on the rear of the pump on what i think is the governor.   There's a yellow tag towards the bottom of the main pump housing that appears to be a MACK reman tag with the numbers PLM450 205D, 5161P14X and SER#RC10591.  maybe that's the number your looking for?  I sure wish I could upload pics.   the engine serial number is 97SB1072CP I think.  there's two tags both with a lot of numbers and none are real clear which one is the Serial.  the one that says serial is E6 350 NRB, but that seams like an engine model to me.  the truck is an 89, but the engine and pump were rebuilt by Mack in 1991 for reasons I don't know.  I guess I'm not even positive its the original engine,  but that really shouldn't matter here.  

[Joey Mack]

Yeah, i was thinking, pre 1990 yes to ambach. After that, Robert Bosch.  So then i though the yag is a rebuilders tag.  

[elm]

So i think the pump is an Ambac PLM450 205D.  to  many different numbers on it!