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Jetcat fuel pump

Old 09-28-2020, 04:47 AM
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ledd4u
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Default Jetcat fuel pump

Interesting situation. I have a P-120 with Kerostart. My original pump worked perfectly. I decided to buy a new one for my new jets first flight. I got the pump from Dreamworks just about a week ago. I installed it and performed the prime pump procedure. All good. Then I set 1 = U-accelr1setting for the correct fuel flow. Now keep in mind the start voltage for the pump prime is .500 volts. The U-accelr1 is for the correct voltage so that the fuel is delivered in a thin fuel stream (a little bit more than just dripping out of the tubing). To test this, press the ďRunĒ key several times to check that the pump starts steadily running on different pump rotor positions. My setting was at .200v. My engine did not start, it timed out. I did this several times and was cautious as to not flood my engine. No movement of fuel anywhere. The Kerostart fuel line also had no movement. I removed it and installed my original pump back in and normal operation. May I have gotten a pump thatís to tight and needs a higher voltage less than the .500? The manual says itís between .100-.300 volts. I will call Dreamworks today and see if I can get a new one
Old 09-28-2020, 09:39 AM
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Dave Wilshere
 
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It’s not the pump but the motor not starting at our super low figures. They are 6v motors and quality is not what it was, I run fuel through for an hour or so to bed they brushes in.
You might need to talk to George about increasing the pump rattle figure

Dave
Old 09-28-2020, 09:46 AM
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ledd4u
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Thanks Dave! Spoke to dreamworks RC Jose. He recommended removing the two fuel feeds. Main engine and Kerostart and place both lines in a small tank. Adjust voltage to get the required flow. It ended up being .300. Both seem to work now. He explained that these motor/pump have to be kind of broken in. I ran it about an hour on a 1.2 volt battery and a small tank of Jet-A prior to the above. Kind of explains why my engine timed out. He also mentioned to keep an eye out for engine flame out of the back. He said once it sets in I might have to reduce the voltage. My original pump setting was .175v
Old 09-28-2020, 09:47 AM
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ledd4u
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Originally Posted by Dave Wilshere View Post
Itís not the pump but the motor not starting at our super low figures. They are 6v motors and quality is not what it was, I run fuel through for an hour or so to bed they brushes in.
You might need to talk to George about increasing the pump rattle figure

Dave

whats the pump rattle figure?
Old 09-28-2020, 09:57 AM
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Dave Wilshere
 
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The ECU will adjust to a degree as the brushes/pump bed it. I have been as night as 0.350 on new pumps without much flame. Pump rattle is the pulsing strength on the pump start voltage. It’s not user accessible without codes.
What you have should work.

Dave
Old 09-28-2020, 12:55 PM
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ledd4u
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Ok. Seems the ECU applies a pulse shaped voltage per your explanation. Thanks again.

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