GE Frame 5 Gas Turbine-High Pressure Fuel Pump will not build pressure

Fuel supply to the pump has been verified adequate and the pump is being rotated by the clutch yet the pump will not build any pressure at all. Suspect the liquid fuel bypass valve may be the issue? This unit has been down for several years and is in the midst of a restart/commissioning. The bypass valve has been changed out and is brand new. Any help will be greatly appreciated.
 
Fuel supply to the pump has been verified adequate and the pump is being rotated by the clutch yet the pump will not build any pressure at all. Suspect the liquid fuel bypass valve may be the issue? This unit has been down for several years and is in the midst of a restart/commissioning. The bypass valve has been changed out and is brand new. Any help will be greatly appreciated.
Hello All,
1968Jeffl,

Are you operating turning gear or ratchet on this unit ?
Do you get&follow OEM maintenance & operation procedures?

There are some thread on this forum related to Frame 5 HP Fuel pump&Flow divider issues, Here is one these thread that you can check for more informations on this case:
https://control.com/forums/threads/turbine-failing-to-ignite.43848/

That's what i can suggest you to do at the moment.

Without to be able to check P&ID as built of your unit , I cannot add more statement.

Hope this thread can help,

Controls Guy25.
 
It is extremely difficult to verify the polarity of the servo current(s) being applied to a liquid fuel bypass valve--there are no LVDTs and the valve stem is not visible. Compound that with the fact that if a Mark* IV or -V turbine control system is being used it is difficult to apply servo current to a servo without LVDTs.

If we knew the type of turbine control system we might be able to offer some kind of procedure for testing the LFBV (Liquid Fuel Bypass Valve). Sometimes, it's possible (but messy!) to open the valve and observe movement of the plug when changing current polarity. Sometimes, it's necessary to flow liquid fuel through a cranking unit (so the fuel pump will be rotating) and change the current. ( have seen people use a 9 VDC battery to provide the current to the servo for this test).

If the pump won't build pressure, it could be because the servo current polarity is incorrect, or the pump is bad (I have seen where the internal clearances were destroyed by rust and other debris), or the relief valve is relieving all the time. Usually, there is one detent on the manual valve handle of the liquid fuel flow divider which shows fuel inlet pressure to the high pressure liquid fuel pump, and one detent which shows discharge pressure from the pump. The liquid fuel pressure has to be higher than the liquid fuel check valve cracking pressure (usually about 100 psig) in order for fuel to flow into the fuel nozzle/combustor.

But, it's usually either the pump has failed, or the relief valve has failed, or the bypass valve is not working (including the polarity of the current passing through the servo valve is not correct). There can't be too many other problems.

Well, since this is a dual fuel machine, it could be that the atomizing air check valves are all leaking and preventing fuel from getting to the fuel nozzles. BUT, that would be evidenced by flow through the Tell-Tale Leak-off, usually under the walkway of the right side of the Turbine Compartment, when fuel was being sent to the fuel nozzle but was leaking through a non-sealing atomizing air check valve).

Please write back to let us know what you find and how you resolve the problem! (And, if you need more help, we need to know what kind of turbine control system is in use on the unit.)
 
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