Port Engine Use More Fuel That Starboard

[DRS]

OK folks I need to tap the collective genius that resides on this forum. I have a 2000 lagoon 380 with Volvo MD2030C engines with approximately 5000 hours on them. Just recently we have notice that the port side seems to be using more fuel than the starboard side over the same time frame. Last time out the port tank took on 38L and the stb took on 20
Here's what I know so far:
prop is not fouled
engine is not making oil so its not going there
no diesel smell or traces of it in the bilge so its not going there
no visible smoke (white or grey or blue)
no furnace or other user on the port fuel tank

Looking for input and possible causes. Any and all help appreciated

Derick

[FlyingCloud1937]

Put a laser tac to each engine at cruise speed, and compare to the helm tacs. I'm sure you don't have pyro meters, as it seems not a factory install thing...but they invaluable for providing information.

So that being said, have a look at the the alignment of engine to prop shaft. You would be surprised how much this issue can effect power use required, also inspect your cuttless bearings.

Lloyd

Originally Posted by DRS

OK folks I need to tap the collective genius that resides on this forum. I have a 2000 lagoon 380 with Volvo MD2030C engines with approximately 5000 hours on them. Just recently we have notice that the port side seems to be using more fuel than the starboard side over the same time frame. Last time out the port tank took on 38L and the stb took on 20
Here's what I know so far:
prop is not fouled
engine is not making oil so its not going there
no diesel smell or traces of it in the bilge so its not going there
no visible smoke (white or grey or blue)
no furnace or other user on the port fuel tank

Looking for input and possible causes. Any and all help appreciated

Derick

[Terra Nova]

Originally Posted by DRS

...Last time out the port tank took on 38L and the stb took on 20...

Either the tanks did not start out equally full, or they were not topped off equally.

One engine did not burn nearly twice the fuel of the other.

[St. Elsewhere]

If you are using float type fuel gages to determine when the tanks are full, you may have an accuracy problem with one of them. Sight gage tubes on the tanks should be accurate.

[pistarckle]

Maybe the return lines go only to one tank ?

[Cheechako]

Originally Posted by pistarckle

Maybe the return lines go only to one tank ?

Ya, or do you know if the tanks are really separated/dedicated to one engine? My earlier Lagoon wasn't...

[St. Elsewhere]

Originally Posted by pistarckle

Maybe the return lines go only to one tank ?

Also, does your boat have selector fuel valves? Maybe both engines were switched to the same tank.

[Arthur Garfield]

Hi,
%90 difference.Agree return lines going to one tank.
Or-do you use one engine for electric generation therefore running longer?

Do speed test at same RPM to see if on engine requires more fuel to achieve same speed.


All the Best

[DRS]

thanks for all the replies. Here is the report I got from the last user
Port Engine Starboard Engine
Upon Departure - Sept. 17
Fuel Gauge Full Full
Fuel Top Off 7 litres 15 litres

Upon Return - Sept. 21
Fuel Gauge 1/2 Full 7/8 Full
Fuel Fill Up 38.4 litres 20.7 litres

My assumption is that the top off was till they could see it at the filler.
I don't believe they return to a single fuel tank as this is a new occurrence. That and the tanks are 20 feet apart.
Ill check the fuel shut off valves to see if one is not open all the way but again I don't believe the fuel systems are tied together

Derick

[StuM]

Do you have engine hours for the period 17-21 Sep?

Could they have been motoring on one engine?

[DRS]

we ran the port engine for 21.1 hours and the starboard engine for 21.3 hours.

Sorry I missed including that part of the report