721D running rough at 1/4 tank

[GHdiesel6]

This problem just started...Mower runs fine for an hour then the rpms drop and almost dies, wait a minute and the rpms pick up and when you start moving the does it again. Looking at the fuel return line you see that there is not a lot of fuel running through the line, even looks like the fuel is just laying there. If I fill the 9 gallon tank up, the mower runs fine till you get below 1/4 tank. I thought maybe water was in the fuel but that wouldn't make sense since it only runs rough at below 1/4 tank.....Any suggestions would be greatly appreciated....Thanks!

 

[BlazNT]

That is so cool you have a low fuel warning system.
Have you checked your fuel cap to see if it is venting correctly?

 

[GHdiesel6]

I have not checked the fuel cap...I did just buy it last year from The Mower Shop...I should check it since now its starting to get dusty cutting here late in the summer! Thanks

 

[GHdiesel6]

Replaced the in-line fuel filter last night and took out the fuel pick-up tube and sure enough, it was plugged with gunk...mower runs great again! At the end of the season i'll drain the tank and remove it so i can tip it over and clean out the tank..

 

[BlazNT]

Its so nice when you can find the problem. Most of the time it takes a long time to find let alone fix the problem.