Stratomaster - Fuel Management System

[cobra]

I have installed a Fuel Flow Sensor with a Fuel Flow Gauge (FF1) on a 583 Rotax Engine with a 77 liter Tank in the following order:

fuel tank 70cm fuel filter 15 cm ff sensor with jet 25cm fuel pump

The sensor is installed in the correct direction and at the correct angle as recommended with a K-Factor of 7000

The engine cruises at +- 16 liter/hour at 5300 rpm.

The problem is that the Fuel Flow instrument only indicates 1.6 to 1.9 liter/hr in the cruise. The wiring is connected correctly as well.

Anyone with advise, it will be appreciated.

[African Grey]

Talk to MGL - Rainier....he'll troubleshoot for you. He makes them and definately will sort it out.

[rainier]

Your symptoms are consistent with the jet not installed correctly.

The jet needs to be inserted into the inlet side and pushed all the way until it hits a stop. It goes in some 2cm and you use the back of a drill bit or something similar to do that. It requires a bit of force.
The jet MUST be located right in front of the impeller or else this thing is going to under read horribly.
Also, take note of the installation tips in the manual. Orientation of the sender is critical in low flow environments and you can get real amazing performance out of the thing just by making sure it has the right orientation to minimize friction on the bearings to almost nothing.

Make sure no vapour can get trapped in the sender during operation. If you have a bubble inside that can't go away, it will seriously interfere with the flow in the chamber and you will never get a good, stable and accurate flow reading.

A good installation should allow you to measure flow rates to errors no more than 1 or 2%.

You will find, once everything works the way it should, this thing will become your most important instrument in flight, specialy during cross countries where it takes the guesswork out of "have I got enough fuel ?" and "how much further can I fly if I fly a little slower ? (You'll be amazed at the answer)".

Rainier

[cobra]

Thanks Rainier (& Russell), spoke to you on the phone this morning. I am sure that the jet is not all the way in as per spec . Your assistance and prompt reply is appreciated.

[cobra]

I have calebrated the fuel tank as instructed (manual FF1). The total fuel in tank is 77L - I used 7L as the reserve (total qty used 70L)

The fuel level worked fine until I reached 63L :D . Currently it indicates 70L total fuel and does not move at all, although the tank only has 50L in. I still have the orginal fuel qty gauge which indicated the correct amount (level sensor works fine).

I went throught the calibration again - when selecting DONE ? and by remaining on the CALIBRATION menu the qty (FUEL menu 3rd from above) indicates the correct amount eg 50L - when i select + or - the FUEL menu defaults to 70L
_______
Indication on display is 0 ---- 70 ?? Lts. Any suggestion on what the problem may be

[Morph]

Siasd,

I had a similar problem with Gadget's fuel level sensor (same MGL FF1). Eventually we removed the fuel level sensor from the tank and using a multimeter across the body and center points of the sensor (set to Ohm/resitance) and moving the arm you would expect a constant increase in resistance from empty, bottom position, to full, top position. We found that this was not the case. At the pivot point is a spring on the arm and this spring should connect with the semi-circular reostat. We found the spring to be weak and not making contact all the way around. By stretching the spring we got a better contact and a better reading on the gauge.

[cobra]

Thanks Morph, i will check it over the weekend as the trike is in Heidelburg. May see you at Rand with Demon - if the problem has not been resolved i will give you a "demo"

[DarkHelmet]

My fuel flow meter works fine unless Big D or FatFlyer (erm... ForensicFlyer) is in the back - they tend to get a bit in the way when I lean over to check the level of the tank and we enter a steep turn to the left when they also try to look with me!!!!

[Ian]

Yep, and mine works like a treat ! :D

Amazing how you can save around 2 L/Hr or more in the cruise by trimming out and watching the flow meter / VSI / ASI

Cheers ian