Cummins Onan genset - how to measure fuel burn - Q for ARE?

[Deleted User YDKXO]

Fair enough. I guess most of us have our degree of OCD-ness.

Yup a classic case of Man Logic to justify buying yet another toy We've all been there

 

[ARE]

Thanks Anthony. That definitively answers the question - if the Kubota's governor is mechanical then there exists no electronic data for fuel injected. "End of", so to speak.

The only sensible answer then is maretron then I think. These need a flow sensor installing on the flow and return to the diesel engine, then they connect easily to the boat's existing N2K network. These feel like they will be highly accurate. They are positive displacement, sort of gear pumps in reverse in fact, so they should measure the volume quite accurately, plus they measure the fuel temperature and adjust for it in the electronics. Maretron is generally top quality gear as you know. They claim +/- 0.25% accuracy so with a pair of them the accuracy should be comfortably better than 1%, which is pretty good. I'll investigate the mechanicals of where to install these and report back - as they use 1/4npt fittings for the fuel lines I think it will be quite easy to install them close to the gensets using a (say) 200mm long new fuel line to go between the genset and the flow sensors, and then connect the existing 1/4npt fuel lines to the other side of the flow sensors, and all done

John,

I would be interested to see how this work's, I can't see any issues with installation as the generator is piped in 1/4npt fittings already.

What is the fuel restriction though the flow sensors?

Anthony.

 

[jfm]

John,

I would be interested to see how this work's, I can't see any issues with installation as the generator is piped in 1/4npt fittings already.

What is the fuel restriction though the flow sensors?

Anthony.

I don't know. It might be on Maretron's datasheets - their website is full of tech info on their products. Thing is that if the genset's pump is doing 80 litres an hour with over 90% returned to the tank you'd expect there is easily enough headroom to cope with a bit of friction in the flow sensors. Plus, if the genset's fuel pump is positive displacement (I don't know if it is) it will just draw a bit more DC current and deliver largely the same 80 lph flow rate even if there is some friction in the flow sensors.

Remember also the Onan installation spec allows for very long flow/return pipe runs and mine are obviously quite short on my size of boat with the gensets right up beside the fuel tanks

So it all feels ok. I'll look at the boat this weekend and then if the installation looks simple enough I'll order the hardware and report back in a while. It's handy that everything is 1/4 npt because I can probably just buy one short pipe to each flow sensor and connect the existing fuel line to the other side of the sensor. Thanks for the input

 

[BigEmUp]

I've looked into this too. A genset will burn an awful lot of fuel if at anchor for a while. If genset use becomes important to monitor, I just dedicate one tank for it and monitor its level. Simple, fairly accurate and costs nothing but a few minutes. If you really must control and monitor everything precisely to the last degree of control then Maretron is the way to go. I reckon you could fit the two sensors and monitor for £600 per genset if you do it yourself. Something else that will break and you have to maintain of course.

 

[jfm]

Something else that will break and you have to maintain of course.

Of course! That's all part of boating