Has anyone had problems with lost power when fuel gets below half a tank when full or near full it runs fine
Probably a weak lift pimp or plugging screen in fuel circuit
We used a Volvo 290 last year that had that problem. We found out theirs a screen in the tank that was full of rust flakes. We were able to clean it by unbolting it from the bottom of the fuel tank. Some excavator brands have them, others don't.
My 9030B had a fuel filter on the side of the fuel tank, you access it from on top. It's about halfway up the side of the tank. I would get a piece of clear fuel hose installed between the transfer pump and the line coming from the tank to look for air bubbles. Obviously do this when it's at the level where you are losing power. If you have air in the fuel, then you'll have to work your way back to the tank to figure out where the air is coming from. Loose filter, loose connection, bad hose are some possibilities. If no bubbles are present, then you're probably going to want to verify transfer pump pressure.
Jimmy48 Thanks for info we have a starting point now
We have a 2700q that had the same problem. After fighting the problem for years we just started replacing things. The first we did was completely replace the pre-filter bolted to the tank, filter housing, supply line and removed, drained and cleaned the tank. It fixed the the problem and the machine has been running like new. If I had to do it again, I would just replace the filter first. We did the whole unit since we couldn't get the element. Search my name for the thread I created. There were a bunch of other ideas too.
I agree, it sure sounds to me like it's drawing air when the fuel level gets below the filter level.
Our issue wasn't air but it was just crap in the line between the tank and pre-filter that would move to the pre-filter and plug it. Turn the machine off and it would pull away from the filter enough for the fuel to flow for a bit, then it would choke the machine out like it was getting air. It started when we had less than the half tank of fuel and progressively got worse til it would always do it.