Simjet 1200 starting problem
03-09-2013, 12:00 PM
#1
Simjet 1200 starting problem
I recently acquired a Simjet 1200 AES. I would guess it's about 5 or 6 years old.
At first I couldn't get it started at all. Figuring I had a bad propane solenoid valve, I bypassed it and got several successful starts. The turbine ran perfectly. That was a few weeks ago.
After lubricating the solenoid and properly seating the tubing, I went out to try a fully automated start today.
Everything worked, up to a point. The propane solenoid would sequence perfectly, the turbine would light off on the propane and start to ramp up, then maybe a few thousand rpm later it would shut itself down, usually with a residual flame and lots of smoke out the tail. I tried it a dozen times and got the same result. I tried it bypassing the solenoid as well.
I found the surest way to get a start was to just crack the propane valve, not even going to the first click.
Any idea what could be happening? This scenario does not appear in the manual.
At first I couldn't get it started at all. Figuring I had a bad propane solenoid valve, I bypassed it and got several successful starts. The turbine ran perfectly. That was a few weeks ago.
After lubricating the solenoid and properly seating the tubing, I went out to try a fully automated start today.
Everything worked, up to a point. The propane solenoid would sequence perfectly, the turbine would light off on the propane and start to ramp up, then maybe a few thousand rpm later it would shut itself down, usually with a residual flame and lots of smoke out the tail. I tried it a dozen times and got the same result. I tried it bypassing the solenoid as well.
I found the surest way to get a start was to just crack the propane valve, not even going to the first click.
Any idea what could be happening? This scenario does not appear in the manual.
03-10-2013, 02:19 AM
#2
RE: Simjet 1200 starting problem
Hi Dustflyer
What you may look for is a low temperature during start. If you use to little propane during starting the temperature will decrease during ramp up, before the fuel ignite. If the temperature gets below 80-100°C it will shut down.
What you may look for is a low temperature during start. If you use to little propane during starting the temperature will decrease during ramp up, before the fuel ignite. If the temperature gets below 80-100°C it will shut down.
03-10-2013, 04:55 AM
#3
RE: Simjet 1200 starting problem
Thanks very much for replying!
This engine uses an external propane tank. It seems the only way I could get it to start was to just barely crack the the regulator valve. If I open the valve any more than that it won't start at all. In fact, the manual says the most common cause of starting problems is too much propane.
It sounds like what I need to do is just crack the valve at first, then once the engine starts ramping up start opening the valve a lot more. I tried that a couple times and it made it to a higher rpm but still shut down. Maybe I didn't open the valve enough. I'll give it another try.
This engine uses an external propane tank. It seems the only way I could get it to start was to just barely crack the the regulator valve. If I open the valve any more than that it won't start at all. In fact, the manual says the most common cause of starting problems is too much propane.
It sounds like what I need to do is just crack the valve at first, then once the engine starts ramping up start opening the valve a lot more. I tried that a couple times and it made it to a higher rpm but still shut down. Maybe I didn't open the valve enough. I'll give it another try.
03-13-2013, 12:33 AM
#5
RE: Simjet 1200 starting problem
Do you have a data terminal that you can connect to the ECU.
You will have to look for what your temperature reading and rpm are doing.
If I understand it correct, it blows out if you are using too much propane, if that is the case. It may be that the high flow of propane is pushing the flame out of the combustion chamber during start.
Ore try to contact Kerry he is in Bath PA, www.ussimjetllc.com
You will have to look for what your temperature reading and rpm are doing.
If I understand it correct, it blows out if you are using too much propane, if that is the case. It may be that the high flow of propane is pushing the flame out of the combustion chamber during start.
Ore try to contact Kerry he is in Bath PA, www.ussimjetllc.com
05-09-2013, 11:51 PM
#7
RE: Simjet 1200 starting problem
Have you change the glow plug? Is it the same one since you got it? Some times they glow but are not hot enough to start the engine, if you think you are using to much propane you can restrict the line using a collar and using the screw to squeeze the line close to your needs.
You can also try a lighter during start at the tip of the temp sensor wire to make the FEDEC think it is hot enough to continue the starting sequence.
Don't be surprised if the temp prob ( wire) is bad, some times they go bad after not been used for some time.
All these are suggestion to find the problem.
Good luck
You can also try a lighter during start at the tip of the temp sensor wire to make the FEDEC think it is hot enough to continue the starting sequence.
Don't be surprised if the temp prob ( wire) is bad, some times they go bad after not been used for some time.
All these are suggestion to find the problem.
Good luck
05-10-2013, 05:30 AM
#9
RE: Simjet 1200 starting problem
Thanks for the tips.
My Simjet is starting and running fine now. I believe the problem was threefold.
1) Inexperience with UAT. My Hotspot doesn't use one. I was trying to start the Simjet when the UAT was half full.
2) Wrong glow plug. I was using OS 8's. These are too short and too fragile. I had the element break loose on two of them. You need to use a heavy duty, cold plug with thick wire, like a McCoy 9 or Rossi 8.
3) Wrong ECU battery pack. I was using a new 8-cell 1500mAh Nimh pack. Too small. The starter motor on the 1200 can momentarily draw up to 20amps. I switched to a 3200mAh 3S LiPo. Big difference!
My Simjet is starting and running fine now. I believe the problem was threefold.
1) Inexperience with UAT. My Hotspot doesn't use one. I was trying to start the Simjet when the UAT was half full.
2) Wrong glow plug. I was using OS 8's. These are too short and too fragile. I had the element break loose on two of them. You need to use a heavy duty, cold plug with thick wire, like a McCoy 9 or Rossi 8.
3) Wrong ECU battery pack. I was using a new 8-cell 1500mAh Nimh pack. Too small. The starter motor on the 1200 can momentarily draw up to 20amps. I switched to a 3200mAh 3S LiPo. Big difference!
