Fuel economy issue.

[QBhoy]

I’m not sure the fuel pressure is your issue. 40 psi on a gauge with unknown calibration might be guessing or close enough. 3 bar is less than 45 psi with a bar being 14.7 psi.
might have missed it but where is your fuel economy figure coming from ? The smart craft ?

 

[QBhoy]

How would it compare to this guide in gallons per hour at certain rpm. I’ve found this pretty accurate comparing to the smart craft. Flick through to your engine.

https://www.boat-fuel-economy.com/mercury-mercruiser-3.0-181-fuel-consumption-us-gallons

 

[DK Diver]

I’m not sure the fuel pressure is your issue. 40 psi on a gauge with unknown calibration might be guessing or close enough. 3 bar is less than 45 psi with a bar being 14.7 psi.
might have missed it but where is your fuel economy figure coming from ? The smart craft ?

I have a Garmin flow sensor. I have thought it could be wrong but for 3 years it was better than now, and it dropped the economy in a split second. I burn 20 percent more fuel on the same trip, several trips in a row.

 

[DK Diver]

How would it compare to this guide in gallons per hour at certain rpm. I’ve found this pretty accurate comparing to the smart craft. Flick through to your engine.

https://www.boat-fuel-economy.com/me...ion-us-gallons

Holy Cow that fuel flow chart is almost spot on with my previous (good) economy. I used the mpg chart and it calculated 2.5 MPG @ 3500 RPM @ 30 MPH. So maybe I'm not crazy. Usually I have 6 dive tanks, 2 180lb divers, lots of gear and ice, and still got 2.4 MPG on a flat day.

 

[QBhoy]

I have a Garmin flow sensor. I have thought it could be wrong but for 3 years it was better than now, and it dropped the economy in a split second. I burn 20 percent more fuel on the same trip, several trips in a row.

If you can. Get a vessel view mobile. It’s deadly accurate for things like exact rpm and fuel burn etc etc. All taken from the ecu. The fuel consumption it to the tiniest detail accurate from injector use. Amazing bit of kit for not much money. Shows fault descriptions, more engine data range time left etc etc. Amazing.

 

[DK Diver]

If you can. Get a vessel view mobile. It’s deadly accurate for things like exact rpm and fuel burn etc etc. All taken from the ecu. The fuel consumption it to the tiniest detail accurate from injector use. Amazing bit of kit for not much money. Shows fault descriptions, more engine data range time left etc etc. Amazing.

I have considered Vessel View. I assume the unit mounts in the engine bay. It will not pinpoint the problem I am now having, but it would be nice to have to monitor my system. We are in the remote islands of the Bahamas for months at a time, so it would take a lot of guess work out of any alarms. The Rinda will go on the trips as well.

 

[DK Diver]

Looking back at my notes I see where I had 165 at idle and the temp dropped as RPM's climbed. At cruising speed, 3500 rpm, Rinda reads 155 degrees. Although the seawater coming in is cooler now, 60 degrees, the engine temp should stay up shouldn't it? At WOT would the temp rise a little with a properly working thermostat? And, would 155 degree engine temp cause a rich condition/increase fuel consumption?