12-24-2014 04:42 AM
That was excactly what was wrong. After checking the wiring to the actuator, it turned out, that one of the wires to the actuator had nearly broken off the pin in the plug at the actuator so every now and then it would loose contact.
When that was fixed, the engine wouldn't start, and when measuring the resistance in the actuator, it was at about 3MOhm, so we had to change the actuator as well.
Engine has now been running fine since.
I highly appreciate the help with the faultfinding.
Have a very merry Christmas.
12-23-2014 03:37 PM
Since you are using a Woodward hydro-electric actuator, I am assuming that you are using a Woodward 2301A Speed Control. The 2301A uses a 0-200 mA current into the 35 ohm coil impedance on the actuator. Therefore the voltage across the actuator should never be more than 7 Vdc. If the voltage across the actuator is going to 20 Vdc, then what you are measuring is the internal power supply voltage of the 2301A. To me it sounds like you have a wire going to the actuator that is opening up, or maybe a terminal screw that is not tight enough. Let us know.
12-21-2014 05:56 AM
We have a 3508 engine, which has just been rebuilt after a breakdown, and now it is causing some running problems.
When the engine is started in idle at 1800rpm all pressures and temperatures look fine. Then after a period of 5-15 minutes of running either in idle or under load, the engine stops without prior warning. The Woodward actuator is at a setting of 2.2 V DC until the stop signal and rises then to 20 V DC - causing the fuel lever to go to zero. The magnetic pickup is at a steady 5.5 kHz equivalent to 1800rpm.
What can cause the engine to stop without any warnings. There are no alarms present and no indications that the engine should perform a stop. Furthermore, the stop signal relay stays un-energized at all times as well.
Type: 3508 DI-TA/1
Serial no: 23Z07600
Built year 2000
Solved! Go to Solution.