2006 RTV 900 starts hard when less that 1/2 tank of fuel

[Sweptwing]

hey everyone. My rtv 900 starts hard and even sometimes starts and dies when starting cold when the tank is less than 1/2 full. It sounds like it is starving for fuel. Is there a check valve I need to be looking at that is perhaps allowing fuel to drain from the high pressure pump when it sits like this? Thank you for any info you may have.

 

[atsah]

I wonder if the fuel cap is causing a venting problem. Take it off and try to start it with half a tank.

 

[Sweptwing]

Might have come up with something. This morning it will not start at all. There is still about 1/4 tank of fuel. There is fuel in the filter. When I take the hose off of the fuel pump and crank it over nothing comes out. Could it be that the high pressure pump has enough suction to draw fuel when there is 1/2 tank of fuel yet when it gets low it no longer does? This makes sense to me. So thinking the lift pump is out. Now how hard to replace and expensive are those things?

 

[atsah]

Maybe the fuel pump is weak and the weight of a full tank is pushing down enough so that it runs, fill it and see what happens.

 

[atsah]

The injector pump doesn't suck fuel, the lift pump feeds the injector pump.

 

[atsah]

the cap could be causing vacuum, did you take it off and try it?

 

[Scook222]

I can’t remember what the hose looks like inside. If there a screen and hose in the tank, if so it could be alittle trash in it or you might have an algae problem. We never had problems with algae in diesel until the years we had lots of rain. You can unhook the line at the tank and see how quick it comes out and that should tell you if you do. There is a diesel treatment for it but you have to change the filter several times is the algae was bad. The filters won’t look dirty but the line and filter would be stopped up.

 

[RjCorazza]

Sure sounds like a bad lift pump. Most current Kubotas use a small 12v electro magnetic pump. If your machine has one, you should hear it clicking away with the ignition in the run position.
The Kubota pump is expensive (really expensive). There are plenty of quality aftermarket pumps available at a more reasonable price. Mr. Gasket makes a nice 12v pump for diesel and can be found for 30-45 bucks.

 

[Sweptwing]

This one has an engine driven pump. It was putting out nothing but when you have enough fuel in the tank it would allow enough of it to the high pressure pump to continue to draw fuel. I made a cover to blank off the fuel pump mount on the motor much like you do on an automotive engine. I bought a $10 12v electric pump and think that will do the trick. I like electric pumps better anyway since I can actually hear if they are working. Will let you know the results but I'm confident this is the issue. As far as the fuel cap recommendation I would have agreed that could have been a possible problem except usually those issued rear their ugly head only after fuel has started being drawn from the tank not after sitting overnight. thanks all of you for the insight. Will post the results tomorrow when I have time to completely finish the project.

 

[007kubotaguy]

This one has an engine driven pump. It was putting out nothing but when you have enough fuel in the tank it would allow enough of it to the high pressure pump to continue to draw fuel. I made a cover to blank off the fuel pump mount on the motor much like you do on an automotive engine. I bought a $10 12v electric pump and think that will do the trick. I like electric pumps better anyway since I can actually hear if they are working. Will let you know the results but I'm confident this is the issue. As far as the fuel cap recommendation I would have agreed that could have been a possible problem except usually those issued rear their ugly head only after fuel has started being drawn from the tank not after sitting overnight. thanks all of you for the insight. Will post the results tomorrow when I have time to completely finish the project.

Lift pump. I have seen this problem many times. Good Luck Lance

 

[Sweptwing]

Lift pump. I have seen this problem many times. Good Luck Lance

Put on a $10 electric fuel pump from amazon and it runs like it hasn't in a long time. Also while I was at it I turned up the fuel on the injection pump 2 turns so now isn't quite so doggy and will roll a little black if I want it to. Thanks everyone again. Next project is to adjust the hydrostat so If you get stuck on a hill you can still get it out of gear. Doesn't seem to be getting completely to neutral at idle.

 

[ovrszd]

The injector pump doesn't suck fuel, the lift pump feeds the injector pump.

Absolutely correct.

 

[ovrszd]

Put on a $10 electric fuel pump from amazon and it runs like it hasn't in a long time. Also while I was at it I turned up the fuel on the injection pump 2 turns so now isn't quite so doggy and will roll a little black if I want it to. Thanks everyone again. Next project is to adjust the hydrostat so If you get stuck on a hill you can still get it out of gear. Doesn't seem to be getting completely to neutral at idle.

Glad you figured it out.

The HST issue is a tough one. There are some adjustments that can be made to make it easier to get out of gear. The most effective is patience. Hold the brake pedal down, wait 2 seconds, then try to get it out of gear.

Do you have a Shop Manual?

 

[Sweptwing]

Glad you figured it out.

The HST issue is a tough one. There are some adjustments that can be made to make it easier to get out of gear. The most effective is patience. Hold the brake pedal down, wait 2 seconds, then try to get it out of gear.

Do you have a Shop Manual?

Ya that seems to work sometimes but there are other times on a steep grade where I have had to shut the engine down to get it out of gear. I don't have a physical shop manual but do have some PDF pages on it. Nothing about adjusting the shift cables that I have found yet.