the cummins vt-225 in my grove crane 50,000 lbs seems to not even try when im lugging up hills. no smoke or turbo noise just runs smooth. it has a lot of blow by but uses no oil and starts instantly no matter how cold it is. this is the engine that also runs the boom so it sees a lot of idling and no real load throttle. from what ive read it has a diaphragm on the injection pump that may be bad? the turbo looks and spins good inside but I have not put a boost gauge on it to test. is really seems like its just not getting enough fuel when its under load. it also has a lot of blueish smoke while idling. it clears up a bit when its not but always has a bit of a cloud. any info whoild help maybe a pic of the location of this diaphragm.
My first question would be is this something that just started or has it gone on for some time? Next would be are you sure you are getting full travel on the linkage? I had a crane with a Detroit in it this summer that people though had a bad transmission and the real problem was a messed up throttle cable mounting bracket. Once that was fixed transmission was just fine. Does your pump look like this one? If so there is a diaphragm under the cover with the three screws on the side. One other thing that comes to mind is if your pump is like the one in the picture and has the control lever on the housing like the one behind the red shut down solenoid in the picture you could remove this housing and check to be sure the set screw holding the internal lever on the shaft is there and tight. That was one problem I had a couple years ago myself. Had to edit this as I went to my files and found that problem was back in 2003! Time sure flies when you're having fun. What lead me to that area was I had the engine running with the throttle linkage off and noticed what seemed to be lots of free movement in the shaft before there was any effect on the engine speed.
it has been slow as long as I have owned it and the previous owner never drove it on the road but had it trailered for lack of a proper licenses. from what I cant find that 3 bolt plate? the pump is buried pretty deep under the turbo and whatever magic the Willams air control does. the air control is just for the rear facing position and the front driving position has a cable. the side of the pump has what looks like a splined shaft with nothing on it? also I have a ton of blowby that comes from the fuel tank when you remove the cap with it running.
Any chance of a couple pictures of the pump from different angles? I almost always prefer to work on inline engines as things are easier to see and work on, at least the older engines were. The VT1710 V-12 Cummins were not too bad! Does it have the other shaft like the one in the picture? I'm thinking the splined shaft with nothing on it is normal, that is how they are if they have the other control. It's been a few years but I think what you have is a variable speed governor. That other shaft would be where the governor control for a truck engine with a limiting speed governor would have it's linkage connected. I would try disconnecting all linkage from the pump and try operating the pump directly by hand and not if there is any wasted movement in the control lever that does not effect the engine speed.
The top throttle shaft is for variable speed governer and the lower splined shaft is for automotive governer. One of the shafts will be blocked open. Only one shaft can be used. If it doesnt have a lever on the splined( automotive governer shaft ), then it is probably set up to use the VS governer. In this case, the splined shaft shouldn't move. Once you make sure that you are getting full throttle. Start checking for fuel inlet restriction, and for sucking air. You can get a fitting to put in line with fuel inlet fitting. Then install a gauge that will measure negative pressure in inchs Hg. It shouldn't pull over about 5 inchs Hg at pump. The diaphram in the AFC valve. It won't allow fuel rail fuel pressure until it gets enough boost pressure signal from the signal line running to it. If you are getting full throttle, you have no excessive inlet restriction, or no air in the fuel, check fuel rai pressure with a gauge. You can install a line at the shut off valve housing where that 1/8 th pipe plug is and then hook it to a pressure gauge about 0-330 psi. Dribe truck if possible and check pressure under load. You will have to get the spec. for that pump code which should be on a tag on the pump. You should probably see about 140-150 psi at rated engine speed. Not to be confused with the governed speed of the engine. The gauge will show just over 0 psi at idle. Also don't overlook air intake problems. Good luck!
Dont always assume the pump. Ive seen fuel suction lines collapse or swell shut.