Old wren help
#1
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Join Date: Mar 2015
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Old wren help
Hi I brought a secondhand model with a old wren in it. I thought he had serviced it but I am having trouble and need help!
So I will try and exsplain what happens. Its a wren 54 gas start. I have set the gas valve to one and half turns out as per the manual. However I don't get the pop until about 2.5 turns out. The glow plug is strong and nicely pulled out. So at 2.5 turns it starts up with a god lot of blue flame. The turbine increases in speed to the ramp point. Then it seems to slow some and the. Flames out saying low RPM.
I am stuck anyone?
So I will try and exsplain what happens. Its a wren 54 gas start. I have set the gas valve to one and half turns out as per the manual. However I don't get the pop until about 2.5 turns out. The glow plug is strong and nicely pulled out. So at 2.5 turns it starts up with a god lot of blue flame. The turbine increases in speed to the ramp point. Then it seems to slow some and the. Flames out saying low RPM.
I am stuck anyone?
#6
Sounds like its not switching over to Kero after lighting off on gas, could be a weak battery or something not right with the fuel pump or valves. I would use the test mode to test fuel flow to insure pump and valves
are working with no obstructions in any lines, also check to see if the temps are rising after a light on gas. A word caution do not start the engine to much on gas if its not getting kero because that will destroy the bearings.
are working with no obstructions in any lines, also check to see if the temps are rising after a light on gas. A word caution do not start the engine to much on gas if its not getting kero because that will destroy the bearings.
#8
Does the ECU show ‘fuel ramp’ before the low RPM? Does it light on the kero and not ramp, or not transfer over to kero at all?
What temp does it get to? Are the RPM indications correct?
What temp does it get to? Are the RPM indications correct?
#9
#11
Seems that battery should start it, also check the things that slick 33 suggested. I assume you have purged the fuel lines and fuel is right at the engine and you should be able to see the fuel in the line and observe if
the fuel starts to move as soon as the engine lights of on gas, if not it would suggest the ECU is not seeing a temp rise although I would think it would indicate low temp but it could also be a fuel pump or valve issue.
I dont own a Wren but I have a friend that has one and I am thinking when you check the pump in test mode it receives more power than when at start up and a tight pump may not run but will in test mode.
the fuel starts to move as soon as the engine lights of on gas, if not it would suggest the ECU is not seeing a temp rise although I would think it would indicate low temp but it could also be a fuel pump or valve issue.
I dont own a Wren but I have a friend that has one and I am thinking when you check the pump in test mode it receives more power than when at start up and a tight pump may not run but will in test mode.
#14
My Feedback: (48)
What are your values of PUMP START POINT and PUMP START RAMP parameters?
First make sure that the thermocouple extends about 1/8" to 3/16" into the exhaust cone. If it's not in far enough it won't see enough of a temp. increase and switch over later then it should.
PUMP START POINT - A good default value is AUTO+2. If it's less than that increase it. This sets the pump speed when it first turns on. A higher value will increase pump rpm, lower is slower. If you're getting a yellow flame when the pump first starts then lower the value.
PUMP START RAMP - A good default value is 6 . This parameter sets the pump rate of increase after it initially starts. 1 = slowest and 10 = fastest. If it takes too long to get to idle then increase the number. If you're getting yellow flames during Fuel Ramp then decrease it. The correct value depends on how strong your pump is and your fuel system restriction.
You may have to play with these parameters to suit your application. Use your HDT and pay attention to what the engine is doing during each phase of the start.
Joe
First make sure that the thermocouple extends about 1/8" to 3/16" into the exhaust cone. If it's not in far enough it won't see enough of a temp. increase and switch over later then it should.
PUMP START POINT - A good default value is AUTO+2. If it's less than that increase it. This sets the pump speed when it first turns on. A higher value will increase pump rpm, lower is slower. If you're getting a yellow flame when the pump first starts then lower the value.
PUMP START RAMP - A good default value is 6 . This parameter sets the pump rate of increase after it initially starts. 1 = slowest and 10 = fastest. If it takes too long to get to idle then increase the number. If you're getting yellow flames during Fuel Ramp then decrease it. The correct value depends on how strong your pump is and your fuel system restriction.
You may have to play with these parameters to suit your application. Use your HDT and pay attention to what the engine is doing during each phase of the start.
Joe
#15
My Feedback: (11)
I have stopped using a fuel solenoid with my propane start jets. I've seen them gum up and can have the symptoms you describe.
An easy way to check is to disconnect the fuel line at the turbine and try a start to see if fuel comes out. If you are worried about running your bearing dry, pour some kero down the engine then blow it out and then do a start.
Good luck!
An easy way to check is to disconnect the fuel line at the turbine and try a start to see if fuel comes out. If you are worried about running your bearing dry, pour some kero down the engine then blow it out and then do a start.
Good luck!
#23
My Feedback: (8)
I have settings for Fadec and Xicoy ECUs that I run on my Homebuilt Wren 54s. You can run them in the manual or auto mode. What ECU are you running? Auto start or manual mode? If your flame is coming out at start up it sounds like you are feeding in to much propane. Does your Wren have two glow plugs?
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