Kubota RTV 900x Lost power while driving

[36racin]

Just asking...Could small rocks or dirt from inside the fuel tank make it thru the filter, LP pump and into the injection pump? I guess anything is possible. And from what I have been reading and seeing the Injection pump has some pretty tight clearances....

Has anyone used a off brand injection pump? I can pick those up for mid 400's

Todd

 

[thepumpguysc]

I can handle the pump rebuild for u.. no problem..

It sounds like the pumping plungers are in bad shape, and when u added a new injector, the pressure is probably a couple hundred psi more than your old ones and that’s why it’s not pumping. Not enough pressure to open the injector.

 

[EXPETER]

While out driving the utv(work machine) which has always had 22-25 mph speed capability something happened....Going along and cart instantly lost power and will not go any faster than 12-14mph now. UTV always run on flat ground, gravel and asphalt paved roads. Kubota D902 engine

Removed fuel tank and cleaned(there was actually rocks in it)
Removed fuel hose and fitting out of tank and removed rocks out fitting.
Replaced fuel filter
Replaced one fuel injector
Replaced air filters
Removed muffler to check for plugged spark arrester(none found) but ran/drove with muffler removed with no change in engine performance



After replacing the injector I am still not getting fuel to all the injectors as I believe it should be...One definitely is working correctly and will change how the engine runs when you crack the injector...The other two not so much. Bypassed the LP mechanical pump before the injector pump with an electric pump to test(tank to electric pump to injector pump). Same running condition. I'm beginning to think I didnt have a injector problem to start with and may actually a injection pump issue. Engine doesnt appear to be running up to max rpm's

Any suggestions...I dont want to throw alot of $$$$ at this machine changing parts that may not be needed. We need this machine at work but company not willing to buy us a new one at this time...

Todd

Had a similar problem. My power loss was gradual though. Take a look at the muffler exhaust pipe. There may be a device there whose purpose is to filter carbon deposits. If you clean it out or remove it, your MPH speed capability may increase to 22-25 mph. Mine did. Hope this helps.

 

[hayden]

With a sudden loss of fuel at two cylinders, coupled with discovery of dirt and gravel in the tank that has to have been intentionally or unintentionally introduced, it seems almost certain that the two things are related. In theory the fuel filtration would have caught it, but maybe a fist full of dirt was too much?

 

[36racin]

Update as of 6-13-25. Still having issue. Machine only running on one cylinder from what I see. It will run on one cylinder(not well). I'm leaning towards the fuel injection pump needing rebuilt or replaced. I will speak with a pump guy this coming week. Pulled pump yesterday to see if anything obvious was wrong like broken springs inside the pump....Didn't really find anything. Could be the orings inside the injectiion pump on the two cylinders not working correctly. Wish I could find a known working used unit I could try out before spending $1400 at Kubota. Don't just want to throw parts at it. Machine needs other repairs once the engine part is repaired.

On another note. I have an electric fuel pump off tank installed and using it to provide fuel instead of the mechanical one on the block. On another site I saw mention of a ignition powered on connector in the engine bay to connect the electric pump to. Anyone replace with an electric pump and know where this connector may be located? It said the connectors even matched electric pumps sold on amazon.

Keep the suggestions coming and thank you all for assisting me

Todd

 

[36racin]

With a sudden loss of fuel at two cylinders, coupled with discovery of dirt and gravel in the tank that has to have been intentionally or unintentionally introduced, it seems almost certain that the two things are related. In theory the fuel filtration would have caught it, but maybe a fist full of dirt was too much?

I agree. Not pointing a finger at anyone. But makes you wonder....I too would have thought the filter would have caught the particulates. But if it was fueled with the engine running and with the known amount of stuff I got out of the tank when I flushed it....Then maybe, just maybe something got around the filter and wrecked the mechanical fuel pump, injection pump(cylinders not working) and plugged a few injectors. I thought i had an injector problem so I replace one with a Kubota one. No change in how it ran. I now believe I am not getting sufficient fuel pressure on two cylinders to get it to fire the injectors

Thanks for the assistance,
Todd

 

[36racin]

Just a small portion of what was in tank

 

[thepumpguysc]

Wow.!! Somebody doesn’t like you..??
Yank the pump and send me all the injectors..
I’ll find the problem, if there is one..
Just click on my screen name to “start a conversation”..

 

[36racin]

Update.....It appears it was a injection pump failure. Boss gave me the ok to purchase a new one. Installed it yesterday evening. Cart is running again(kinda) I currently have two cylinders firing...The third has a leak on the injector like I didnt add a crush washer or didnt tighten it up....So I will pull it all down again to tighten or install the washer. On another note the LP fuel pump isnt working as far as I see...I have an electric connected currently with temp power. Guess I will replace the LP pump too. Then its on to a full service and repair the other known issues....

Thank everyone for the assistance. I'm sure I need more help...

Todd

 

[36racin]

Second Update.....Cart is back to running on all cylinders. I did leave the injector loose. Also replaced the LP fuel pump and gasket. which was not working either. Can those pumps be rebuilt?