Splitter hydraulics are simple. Pump runs full speed all the time so as long as there is fluid available at the pump, it will be circulated and will push out any air in front of it.
Standard problems.
1) low fluid or collapsed suction hose = no flow.
2) failed, damaged or misadjusted second stage pressure cutoff in pump. Operates at low pressure, not at high pressure. Or very slowly all the time.
3) failed, damaged or misadjusted system relief pressure in selector valve. Low pressure in entire system.
4) Valve failure allowing bypassing at pressure. Usually affects pressure stroke, not retract, but could be both. We only care about pressure for now.
5) O'Ring failure within cylinder allowing bypassing under load.
After 14yrs of typical use / abuse, it's not uncommon for any of the above to occur.
Before cracking lines and adding a pressure gauge, try a couple things.
The obvious - check the hydraulic reservoir is full and the splitter is level or level enough that the intake has an adequate supply of oil.
Test 1 - cycle cylinder back and forth with no load several times. Cylinder should move back and forth smoothly with no jerkiness. This should purge any air from the hoses and cylinder. Horizontal is preferred - vertical will work.
Test 2 - split something easy. Kindling, birch, ash. Normally splitter should not go into second stage for an easy split. Splits normally - then pump low pressure circuit is okay. Stops moving and does not split - could be pump, valve or cylinder.
Test 3 (pump) - Extend the cylinder most of the way then push the lever to the retract detent and let the cylinder come back on its own. Does the lever pop to neutral on its own? If yes - then the pump is generating a reasonable pressure (more than the detent kickoff, typically into 2nd stage pressures). If not (i.e. stays in retract position with cylinder all the way back) - does the engine seem to load up at all, or not? a) Loads up - pump is generating pressure, but not enough to kick out. b) Not loading up - then not generating much pressure.
Now we need to play with wrenches.
Install a 3000psi pressure gauge in line between the pump and the valve.
Extend the ram all the way to the end, then disconnect the return hose (ram end of cylinder) from the the valve and direct it into a pail. Push the lever to extend and hold for a few seconds.
If the pressure gauge rises to 2000+psi and no fluid comes out the return line - you should be splitting normally.
If the gauge rises to 500-650 psi but no higher - then the pump is at fault. Try adjusting the cutoff pressure in case it's stuck or dirty. If no joy - replace.
If fluid flows out of the disconnected return line, then the cylinder is bypassing internally. Rebuild or replace.
Otherwise it's the valve. Adjust the relief lower (usually out) one full turn and check again. If the valve pressure drops, turn it back in 1 full turn and check. It should return to the starting pressure. Now turn it in until it's at 2000 psi. If adjusting the valve relief does not affect the pressure, valve is bypassing internally and needs replacing.
That's quite the concise diagnostic. And I even understood most of it. Thank you for taking the time.
The short story; I got a little desperate when I needed to be splitting and cold weather is closing in on me here so I had played with the only adjustment I could find and things got worse. So I took that cap off the direction valve and with the motor running and while cycling the ram, turned the adjustment screw in, cycled and turned in some more. I put it in pretty much as far as it would go, again, having no idea what I was actually adjusting (did I say I was desperate?) and cycled the ram a few more times. Dropped a round in and it split with a lot less hesitation. Dropped in a bigger one and it went through too. Didn't ask questions, it was functional & I went to work. So far so good, I've just been wondering how long it might last. (That prick Murphy has been around here way, way too much lately).
So from Eddy's explanation, I'm guessing this "3) failed, damaged or misadjusted system relief pressure in selector valve. Low pressure in entire system." is what I was messing with. Is this an adjustment to make up for wear on the relief valve? Since I think I may have it adjusted all the way in now, should I be looking at rebuilding or replacing this directional valve in the near future? Source for parts?
I am still curious about the pump and the ram seals, although having looked around for replacement options for the ram seals and finding a whole lot of confusion and not much else, I'm very leery of having to touch that cylinder.
The pump, so far as I can tell, has no adjustment on it. At least nothing accessible from the exterior, without removing and opening it up. Any suggestions for getting a better education about these? Being a Troy-Bilt splitter from Lowes, I'm guessing it's a pretty low end pump & maybe just ripe for replacement with something better regardless but I'm going to put this list of diagnostics on the agenda for spring, after the frenzy to get through this winter is over and see what needs to be dealt with and not.
Being terminally behind on wood for heat when winter is closing in on you is bad enough but that, along with this terminally wet weather, everything known to man going wrong and keeping me from getting things done and firewood dealers telling me they aren't selling this year cause they don't have anything dry, I've been riding the razors edge of blowing my cork for so long I feel like I've aged ten years this past month. Also can't stop thinking that after the past several months, this winter may be a winter from hell, on top of everything else.