Fuel Mnagement Question

A

ahill

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Manatee Pocket, FL
On my last trip my fuel mgt gauge started fluctuating at low speed. at 1000 RPM it would read 2.3 gph and gradually step up to 7.3 gph then return to 2.3 and start the process over. At cruising speed the variation is about .6 gph which I think is normal due to varying conditions.
Any one experince this and what is the cause/fix?
 
Whats your engine? Newer Yamaha 4 strokes, by design, run the fuel feed pump at less than 100% duty cycle when the engine is running less than 1000 RPM. GOing from memory they fuel feed pump runs at about 50% duty cycle when engine is at 600-700 rpm idle. So assuming you are running a yamaha 4 stroke then what you are seeing is expected and normal.
 
If you never seen this before on same motor, you have air entering fuel line, or defective flow sensor.

Use the 3/8 inch clear PCV hose technique I recommended on other thread to verify solid fuel column.
 
best I can tell your engine has mechanical fuel feed pumps so the theory I posited above does not apply.
 
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