Volvo 5.0 OSI-GF Fuel Flow Indication

[Mcguiver]

I recently purchased a 2008 Chaparral Signature 310 with 5.0 OSI-GF engines and it has a Raymarine Axiom 9+ multi function display that didn't have the fuel manager display enabled. I had it configured and working for about half a day then it quit working (loss fuel flow indication on port engine). The previous owner told me (per Volvo) on that engine the only interface that would give engine data is an "NMEA 2000/Easy Connect" which is hard wired into the network. I'm trying to determine where the source of fuel flow is coming from so I can narrow down the problem.

My question is where is the fuel flow indication coming from since I couldn't find a fuel flow sensor on a parts schematic?

The engine(s) run fine and the boat has no problem getting on plane or running at 3700-4000 RPM so if the absence of fuel flow on the MFD is due to loss of fuel flow to the ECM wouldn't the engine stumble or backfire is it doesn't know how to proportion the fuel/air mixture correctly?

 

[alldodge]

Don't know just a comment
No way to get "actual" fuel flow info without a sensor. It can reasonably calculate usage based on fuel tables, fuel pressure, tank level and RPM

 

[dan02gt]

Unless you add a fuel flow sensor, the system is getting the fuel flow data from the ECM. It's a calculated value based on the fuel the engine is demanding at any given time.

 

[dingbat]

According to the documentation "NMEA 2000/Easy Connect" does not support fuel flow functionality.

Had to install seperate fuel level and flow sensors to support that functionality on my Garmin

 

[Mcguiver]

Thanks all, my Raymarine MFD was showing fuel flow from both engines but the port engine quit showing it after about a half day and I wasn't certain if was measured or calculated and if calculated how accurate it was. The starboard engine is still showing fuel flow and the only connection between the engine ECMs & MFD are the Easy Connect. I thought there may be a coriolis type instrument built in somewhere since I couldn't find the usual turbine style meter in the fuel system which is what I had installed on my old boat with a Garmin chart plotter as dingbat did.

Does anyone know if they make a fuel flow meters for the 2008 Volvo 5.0 OSI engines that doesn't require installing 1 on the fuel pump suction and another on the fuel return to get fuel consumed? That's a suggestion someone made in a post I'd read but not certain the MFD is capable of that without writing code and pricey having to install a total of 4 low pressure turbine meters. This series uses 2 stages of pumps to feed the fuel rail BUT has a spillback from the regulator so the fuel flow meter would have to withstand the high fuel pressure AND fit between the fuel pressure regulator and the fuel rail.

 

[dingbat]

Constant vent regulation?
Over pressure relief?
How does “vented” fuel get back to the gas tank?

 

[Mcguiver]

I haven't read the control narrative for Volvo but on when I worked as on auto mechanic the regulator adjusted pressure based on intake manifold vacuum via a sensor line and fuel returned to the tank since the fuel pump is constant speed. It appears the regulator depressures to the reservoir on the fuel pump assembly on the Volvo engines. The parts schematic looks almost identical to its automobile counterpart with regard to the fuel rails & injectors. The regulator is #24 (the body for the regulator isn't assigned a number and show separate to illustrate the orings #28 for the regulator).

 

[dingbat]

I haven't read the control narrative for Volvo but on when I worked as on auto mechanic the regulator adjusted pressure based on intake manifold vacuum via a sensor line and fuel returned to the tank since the fuel pump is constant speed. It appears the regulator depressures to the reservoir on the fuel pump assembly on the Volvo engines. The parts schematic looks almost identical to its automobile counterpart with regard to the fuel rails & injectors. The regulator is #24 (the body for the regulator isn't assigned a number and show separate to illustrate the orings #28 for the regulator).

View attachment 368409

The constant speeds pumps I’m familiar with (industrial automation) all vent back into the pump circuit. If that is the case, the usual in-line rotary vane sensor will work.

If you have a dedicated return line as with a diesel, a number of manufacturer make NMEA 2000 totalizers. One sensor in the fuel feed and one in the return line. Unit does the math and broadcast consumption over NMEA

 

[Mcguiver]

I had a moment of stupidity. After I sent the explanation on the differences between auto and marine it dawned on me that I could install the flow meter on the suction side of the pump (between tank and fuel pump assembly) and it would read consumption accurately due to where the fuel return line is located. Brain was still thinking fuel line returned to the tank.

 

[QBhoy]

Hi. This calculation is made using data from the ecu (a measured calculation of fuel used at injectors, proportionate to engine rpm) and additional data like range and lph/gph is measured by referencing the aforementioned and gps speed.

 

[Mcguiver]

Update - updated software on everything; Raymarine Axiom 9+ MFD & Volvo Easy Connect interface and have all engine data displaying again BUT they reversed. Port engine data comes up on Starboard side and vis versa. Tried swapping the engine harness connectors around and leaving the MFD looking at the same interface modules and it's behaving as if the MFD is looking at the engine module address NOT the interface address.

The Volvo Easy Connect app only displays what's coming in from the interface so if I leave the harness connections swapped, I'm running the port engine only but seeing it on the starboard rpms.

If no one thus far has experienced this and has the same set up, I'll start another post with that as the subject.

 

[dingbat]

Update - updated software on everything; Raymarine Axiom 9+ MFD & Volvo Easy Connect interface and have all engine data displaying again BUT they reversed. Port engine data comes up on Starboard side and vis versa. Tried swapping the engine harness connectors around and leaving the MFD looking at the same interface modules and it's behaving as if the MFD is looking at the engine module address NOT the interface address.

The Volvo Easy Connect app only displays what's coming in from the interface so if I leave the harness connections swapped, I'm running the port engine only but seeing it on the starboard rpms.

If no one thus far has experienced this and has the same set up, I'll start another post with that as the subject.

Identify Engines feature doesn't work - third party engine interface installed

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