RTV1100 fuel blues...

[engie]

Ok, just curious what everyone thinks here.

Has new fuel lines, new stop solenoid, new fuel lift pump, new fuel filter, cleaned and drained fuel tank, cleaned spark arrestor, run it without the air intake, etc...

Cranks perfectly. Idles perfectly. At WOT, it runs perfectly for about 15-30 seconds, then falls on it's face. Can hold WOT and sometimes it will catch back up and go again for another couple of seconds before going stupid again, or it might die. If dies, it cranks right back up, and the process starts over.

One thing I did just notice -- looks like the seal behind the lift pump might be leaking a bit or perhaps even the lift pump itself. Seem like the likely culprit? I guess in writing it that seems obvious, but I've had a half dozen "for sure" culprits on this thing that didn't end up being the actual culprit.

 

[dodge man]

Does it smoke at all when this happens? How many hours on the machine. I'd maybe take a fuel line loose after the lift pump, turn the key on and see if it pumps a steady stream of fuel.

 

[ovrszd]

From what I read, sounds like fuel starvation. Not sure yet tbe cause.

 

[leonz]

It is most likely crap plugging the inlet screen in the tank. kubota's are famous for that

 

[engie]

Inlet was cleaned before, and replace this time. Got about 1500 hours on it. Not sure if it is smoking or not when it happens.

What does the seal behind the lift pump actually do?

 

[David_Kb7uns]

Only time had something like that on the RTV1100, the main fuel line from tank was plugged up and fuel would backfeed to the injection pump through the vent line and would only run when tank was full to the cap, once it dropped down it would run out of fuel and die.

David

 

[JOHNTHOMAS]

My F was doing the same thing. Started dying going down hills when pedal released....down hill only. I had forgot to replace fuel cap later and ran over it and replaced it. I replaced the two fuel filters just before running over lid. After the lid run over mine started doing like yours. I replaced the first inline filter and it still did it. I removed fuel line from first inline filter and wrapped my hand around fuel line and stuck the line into the sucking end of a shop vac and sucked out about a quarter gallon of fuel in 10 second bursts and even reversed the vac to the blowing side for about two minutes in bursts. Ran fine for some hours since but I have backup inline filters ready to replace if/when it does it again. Try it if you have a shop vac, may help.

 

[RjCorazza]

If you have a leak at the fuel lift pump there is likely either insufficient fuel being pumped, or air is being introduced. I guess the end result is the same... I would replace it.

 

[engie]

Well, after the 100mi round trip drive to get it, I replaced the gasket behind the lift pump where I thought my leak was, but just in appearance, as I looked at it closely today when this didn't fix my leak, it appears that the fuel is coming from the "through seal" on the primer mechanism inside the pump itself? Also can't tell if the primer deal is actually working or not. I'm pretty fit to be tied at this point. Guess I can replace the pump, but I want to be dang sure that is the problem before I do. Have thrown a bunch of $$ and time at it to get it wrong thusfar.

 

[engie]

Only time had something like that on the RTV1100, the main fuel line from tank was plugged up and fuel would backfeed to the injection pump through the vent line and would only run when tank was full to the cap, once it dropped down it would run out of fuel and die.

David

LOL, can I not extend that line down to the bottom of the tank and just let it roll? I'm at least 75-80% kidding.

 

[Spanner]

Inlet was cleaned before, and replace this time. Got about 1500 hours on it. Not sure if it is smoking or not when it happens.

What does the seal behind the lift pump actually do?

This is the Pick-up strainer/filter at the end of the fuel line in the bottom of the fuel tank - Yes??

Lost of people helping you here and I concur the issue seems to be fuel-starvation.

I would be concerned about your diagnostic procedures which have given you so many "for sure" culprits, none of which have been proven guilty.

( A good advertisment for the abolition of the death penalty, by the way, but that is not a discussion we will enter into here!)

Now you have another 100 mile round-trip to replace a gasket which wasn't the problem either... (Another innocent man hanged).

Have you confirmed fuel delivery from the tank? (If yes, How have you?)
A gravity tank as a temporary supply is often suggested to aid this.
This is a very simple fuel system - No 'Rocket Surgeons' needed.

 

[engie]

There is no pickup strainer or filter inside the bottom of the tank on this machine. Just wide open to the nozzle. "He had this problem before". That's probably what took out the pump. Went to my local kubota dealer a couple of months back looking for those parts -- and were told they didn't exist after he looked at the diagrams. I knew better then, but it wasn't a huge deal worth chasing very long.

I can tell you this much -- I extended the "vent?" hose coming from the injectors to the top of the tank down into the tank, and after just a little bit of roughness(priming from the reverse side, I assume?), the problem goes away and the machine runs well. So, definite fuel delivery problem ahead of the injector pump. All of the lines are brand new, filter brand new, fuel brand new after a good tank cleaning, nipple brand new and wide open, etc. The only possible culprit left is the lift pump it would seem, which is leaky, so it seems a dead giveaway.

 

[Spanner]

There is no pickup strainer or filter inside the bottom of the tank on this machine. Just wide open to the nozzle. "He had this problem before". That's probably what took out the pump. Went to my local kubota dealer a couple of months back looking for those parts -- and were told they didn't exist after he looked at the diagrams. I knew better then, but it wasn't a huge deal worth chasing very long.

I can tell you this much -- I extended the "vent?" hose coming from the injectors to the top of the tank down into the tank, and after just a little bit of roughness(priming from the reverse side, I assume?), the problem goes away and the machine runs well. So, definite fuel delivery problem ahead of the injector pump. All of the lines are brand new, filter brand new, fuel brand new after a good tank cleaning, nipple brand new and wide open, etc. The only possible culprit left is the lift pump it would seem, which is leaky, so it seems a dead giveaway.

"He" ?? You are the second owner?

There should be a strainer in the tank so it is something you can fabricate yourself. Even one of the little red fuel filters B& S use on their small ride-ons or somesuch. The strainer is your first line of defence against debris which can cause issues with your lift pump.

If that (LP) is leaking fuel out, it can be leaking air in. Go ahead and let us know how you go.

 

[Fallon]

I haven't seen anybody mention the air vent for the tank yet... After it dies, open up the fuel cap. If you hear a sucking sound, air rushing in, or the tank inflating, you found your problem. As fuel is pumped out, either or pulls a vacuum in the tank until it can't pump anymore, or air gets into the tank.

Not sure if the vent in a RTV is on the cap or somewhere else.

 

[engie]

"He" ?? You are the second owner?

There should be a strainer in the tank so it is something you can fabricate yourself. Even one of the little red fuel filters B& S use on their small ride-ons or somesuch. The strainer is your first line of defence against debris which can cause issues with your lift pump.

If that (LP) is leaking fuel out, it can be leaking air in. Go ahead and let us know how you go.

I don't own it. It's my preacher's. I do work for him very cheaply but getting really worn down on keeping him going on all his various aging equipment. It would be different if he would let me do routine maintenance and keep the stuff going or would front the $$ to really get this stuff back right. But instead he's one that doesn't do maintenance and let's it go or half fixes until it totally quits. That is when he brings it to me, at which time I'm always left chasing a dozen gremlins/necessities(diagnosing multiple interconnected issues at once is virtually impossible), and my normal process of elimination(I'm an atv mechanic -- certainly not a diesel mechanic) is essentially voided -- because the machines need everything and have been "landscapered" to the point that I have to "fix" a dozen things to fix the initial problem. Although that lift pump on it is a brand new eBay special...

I'm waiting to hear back from him. Probably just grab a new lift pump and a little scared of the cheap online way now. Will go whatever route he wants to go. Seems to be able to get by in a pinch with the vent line extended how it is.

 

[Spanner]

Ok. Understand now. Thought you owned it.
You do what you need to do.
You know the return pipe is not the way to suck the fuel so if the new lift pump is successful you need to re-shorten that pipe so you avoid back pressure.
Good luck. Keep us updated.

 

[kuboman]

There is no screen in the tank as you know, but there is a filter ahead of the lift pump so you will not damage the pump. You must determine if you have free flow from the tank to start, then work your way to the lift pump. Then take the line off on the pressure side of pump and crank engine to see if pump delivers. That will determine at what point the fuel stops flowing.