Oil & Fuel m4900 air in fuel line

[sae254931]

Recently purchased 2002 m4900 tractor ran great first few hours just using it around the farm to haul a trailer to and from with no load on the tractor at all.

Had the opportunity to get some bushogging done ran great the first 20-30 min then started to get in some higher brass and ramped up the rpm and that is when the issues started tractor would lose power i would stop and after a 30 sec or so it would act like it would catch back up and run fine. After a few times of this it just died and wouldnt crank back up i got out and started looking and the fuel pump knob on top of the fuel filter was completely down like it was sucked into a vacuum.

i cracked the nut on the fuel/water separator and the knob popped back up i pumped it several times and it did increasingly get harder to pump as indicated in the manual so i figured the air in the line was out. Then today it died and i got to looking and the knob was once again pulled in and the fuel in the fuel/water separator was about 1/2" from the top. Had to slightly crack the nut again on the separator to get everything back up and running again. Runs fine under no load but under load this trend is continuing to happen does anyone have any insight as to why and the way to correct this

it may run for 10 minutes or 30 but the issue is still there

thanks in advance

 

[C4Ranch]

Whats the service history?

 

[sae254931]

Tractor has 700 hours on it looking at his service records might have just answered my own question engine oil changed every hundred oil filter every 200 all fluids have been changed on schedule except for the fuel filter it recommends every 400 hours it has not been changed or at least he is not recorded it

I'm assuming this would calls the system to suck itself into a vacuum

 

[C4Ranch]

That was where I was going. When in doubt change it out!

 

[sae254931]

Thanks for the help I'll change it out Tuesday lets hope that's fixes it

 

[rbargeron]

Fuel filter life can be long or short depending on how clean the fuel is - and condition of the tanks it has been stored and moved in before it ends up in the tractor.

On one of my L3s there was some debris in the tank (looked like part of a rag) that got drawn in and blocked the outlet tube enough so the tractor ran at low power only. A quick way to clear it was a brief shot of compressed air back thru the tube coming from the tank. Good luck

 

[sae254931]

Ok after taking to dealer and having them drain tanks change filters here is where I am at full tank tractor runs flawlessly. When it gets to half a tank, I assume it's starting to pull out of other saddle tank is when I begin to have issues so I have everything done I need to get done and have time to try to address this situation.
Will someone with experience give me some direction to take this there is clearly something that has the crossover stopped up but I'm not familiar enough with it to have a starting point and I would like to be a little more educated before diving right in

Thanks

 

[Tx Jim]

Having owned a M4900 for several years I can tell you that the fuel is drawn out of RH tank and as long as tanks are """venting""" and crossover hose is open then the level in both tanks should be equal. My M4900 acted similar to yours and local Kubota service manager told me to check for a plugged screen in water separater fuel shut off valve. Sure enough screen was plugged,cleaned screen problem solved.