Kubota RTV 900 help needed

alright thanks for being patient. I wired the throttle wide open and took it for a test run, same results. Here in Iowa there is alot of mud and snow right now, so even on the flat terrain I was unable to go any further than 3/4 throttle without the engine bogging down to a crawl, of course backing it down to 1/2 throttle and the RPM would pick up again and the secondary transmission pump would kick in and I was on my way, slow, but on my way. Bob did make a good point earlier it is hard to condemn the pump so quickly. Now I forgot to note that the lower the gear I am in, the less this seems to be an issue, i.e. in low gear it will not bog down the engine as quickly as if I am in high gear. Now really this just makes sense due to the gearing inside the transmission, and the engine isn't working as hard in the lower gear, but I thought it was worth noting. It also occurred to me that when I tested reverse I wasn't thinking and was testing in my shop, and nice flat concrete, so I tested reverse in the muck and lo and behold it bogged down, not very much, but it was there.
 
So we are believing the problem is in the hydraulic drive system somewhere??

Since you have a spare pump to try, maybe it's time to do that??

I always try to use the K.I.S.S. principle. Seems like we have covered all of the simple tests. Time to get more complex.
 
well I have torn into the pumps and everything seems to be in good working order. that being said there are two shafts, one with two pumps and one with a single pump. There doesn't seem to be any scoring or anything on pumps. the only thing is that the shaft on the left side spins freely in neutral and the shaft on the right side does not turn at all. Does anyone know if this is normal or this an issue? I attached a picture for some visual aid.
 

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you never mentioned weather or not the engine smoked when you lost power? if the pumps and tranny were pulling down an engine that was getting full throttle through the governor you should see black smoke as the engine and governor poured the fuel to the injectors but were overcome by to much load. if you don't see smoke that tells me that the governor isn't allowing enough fuel for the load.
 
that is a really good point. I have not seen any smoke out of it at all. Sorry I forgot to address this earlier. Also I don't feel bad even if everything is tip top in the transmission. It just gives me a little more knowledge of the inner workings and after the 2500 hard hours it has it needed a good cleaning. Do you have a guide for adjusting the governor? I have just ordered a maintenance manual for it but it wont be here for a few days, downside of living in the middle of nowhere I suppose.
 
it might not be the governor. it could very possibly be the primary fuel pump. if the primary fuel pump doesn't put up enough pressure to the injection pump then the result will be an under fueled engine and this usually shows up when the demand for fuel is at its peak. can you check fuel pressure between the primary fuel pump and the injection pump at idle? I have also seem a bad vent in the fuel tank cause this when there is a vacuum fom the fuel being sucked out from the tank. try running it with a loose fuel cap and see.
 
I had noticed when I changed the fuel filter that the flow was pretty slow, so I build a new vent off of the top of the fuel tank and the fuel flowed much more freely, I did that last week with no change or improvement. Unfortunately I am not equipped to be able to test fuel pressure (my tool budget here is pretty low) but when I pulled the lines off the pressure seemed to be good, although that doesn't really tell us if it is not providing enough under a load, and also isn't a very accurate way to tell either.
 
I don't want to be redundant. you understand the fuel pressure i am concerned about is between the injection pump and the primary pump right? probably should be about 20 to 25 lbs. i am not concerned about the pressure at the injectors. yet!
 
and we are back. I could not get my hands on a pressure tester BUT I did have a new fuel pump on hand which I then installed and had no change in condition. It is still bogging down under any load.
 
dagnabbit!! I was hoping for you that it was something simple. also check the fuel cut off solenoid to make sure it is traveling all the way. I seem to remember there is a little spring on the gov control return that can break and cause problems too. does anybody remember where that discussion went? do you have any blow by when the engine is running? have you tried running it without the air filter to see if that make a diff?
 
How are the fuel lines? Had a problem, not with rtv, with fuel line that was old and weak and would collapse under load and cut fuel supply.
 
71sschevelle said:
How are the fuel lines? Had a problem, not with rtv, with fuel line that was old and weak and would collapse under load and cut fuel supply.
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Along the same line, if there's any small cracks or holes, it could be sucking air which would cause problems.
 
alright sorry I haven't responded guys, winter here means everything wants to break down. I checked over the fuel lines and everything seems to be nominal, but next time I head to the dealer I might buy some new hose just to be safe. I have run it without the air filter with no change to condition, and there doesn't seem to be any blow by. I am taking a look at that other forum now to check some things out
 
so I took a look at the injector pump and everything was clean, also there were no broken springs anywhere on the fuel delivery system and everything looked fine. I lowered the bed (hydraulic controls) and I noticed that the engine bogged down real bad, even though i was merely lowering the bed down. After that I raised the bed up and it ran like nothing was going on at all, am I wrong to find that strangely suspicious?
 
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