"Blueskies" wrote in message
om...

"MikeR" wrote in message
...

"Blueskies" wrote in message
. com...

"MikeR" wrote in message
...


No wheel in this one (electrical impulses).



Impulses from what?


Ref: http://203.167.230.122/qiss/scripts/FAQFrame.htm


Title: How does the flow transducer work?
Question/Symptom:
How does the flow transducer work?


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Answer/Solution:
NAVMAN flow transducers are of an optical type. Within the
transducer
are a transmitter and receiver that output an infrared beam through the
body
of the transducer. Inside the transducer is a very precisely dimensioned
turbine running on jewelled bearings. As the fuel flows it spins the
turbine
and the blades cut the infrared beam, which transmits a pulsed signal to
the
fuel computer.



OK, normal stuff. Thanks for the link. The concern from the other folks is
what happens to pressure drop if the (turbine
in this case) wheel seizes up. Usually it will add some pressure drop with
a corresponding restriction to the flow, but
the turbine types pass fluid pretty well even if seized...


They try to address that issue he
http://203.167.230.122/qiss/scripts/FAQFrame.htm

Title: Will the fuel transducer restrict fuel flow?
Question/Symptom:
Will the fuel flow transducer obstruct the fuel supply to my engine?




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Answer/Solution:
The current one-piece flow transducer is rated at a maximum flow rate
of 130 litres per hour (32 US gallons per hour). In modern terms this is a
relatively large amount of fuel especially with the advent of far more
economical engines. In cases where users suspect the flow transducer of
being the cause of a fuel supply problem then it is generally found that the
design of the fuel delivery system is marginal to start with, in other words
adding the flow transducer may be the straw that breaks the camels back but
it is not the cause of the problem. The critical measurement in any outboard
engine fuel system is the total backpressure at full throttle. This is
measured in 'Inches of Mercury'. The absolute maximum acceptable limit
amongst most manufacturers is 7.0 inches of mercury and ideally should be
far less (Always consult your outboard manufacturer for detailed
recommendations). Our fuel transducer creates a maximum backpressure of 1.0
inch of mercury backpressure so even if your manufacturer specified a
maximum of 4.0 inches backpressure then you have plenty of margin for the
fuel delivery system components