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when you say the machine slows down is it every function? When it is slow does it track in a straight line if you try to travel? You said when it swings and is slow and boom up it speeds up, that sort of sounds like one pump is not stroking as swing is a sngle pump function and boom up uses both. If memory is correct this model has the pilot shuttle block behind the cab to activate the pump when a function is selected.
I didn`t go back to every post, but I think you mentioned switching off heavy lift function. There should be no on/off switch for heavy lift as it goes through the controller to only be on for 4 or 5 seconds then the pilot oil to the relief valve is cut off. Not to sound like a ----, but your time would be better spent as well as your $$$$ if you keep asking questions here before you order parts. My $.02
Yep, it was slow on every function. It tracked perfectly straight, just very slow as well, along with every other hydraulic function, once it warmed up. It functioned normal and was fast when it first started up in the morning, but would slow down after working it for a half hour or so. That's been cured significantly now by the increase in pilot pressure to ~700psi (indicated on a not so good gauge, on "out" side of the pilot filter. But now it has this weird slow swing until you just hit the boom up or down.
I'm hope I'm not wrong, but I don't think it's one of the pumps, because I would've thought that it wouldn't track straight, which is what happens if a pump or regulator fails.
We had a different issue a couple of years back where it would lose boom down power (as opposed to being slow- it couldn't lift the machine) unless you just barely touched the travel lever/pedal and then full power was instantly restored. That was diagnosed to be the boom regulator (located under the floor of the cab) which I ultimately replaced, but before I installed the new part, the problem solved itself somehow.
Trust me, I do value these forums as a very valuable tool as there are very knowledgeable people on here, and I wouldn't buy parts unless I thought they were needed.
It's just that the "mechanic" I had first told me that it could be the pump regulator, which we've had problems with before, and was in fact very dirty inside, and so I bought that, then he said it had to be "the computer", so I bought the new PVC. Then when he installed the new "computer" and called me and told me it didn't work, because it turns out, he had not performed the relearn procedure (even though I had loaned him my repair manual), I decided I had to try to fix it myself, instead of paying someone who obviously didn't know what he was doing. Hence, this thread.
Many thanks for your input.
