Metallic debris in return fuel line

I installed Optio fuel flow sensors in the supply and return fuel lines of my Cummins 6BT 5.9-M engine about 6 months ago. The sensors functioned properly until the last cruise when the GPH usage shown on the iPhone app suddenly increased several fold without a change in the throttle. The return fuel line sensor was shipped to the factory. Three photos attached to this post demonstrate debris in the sensor gears. The longer, thinner debris in the first and third photos are composed of a ferrous metal. No fuel system or engine work has been performed since the flow sensors were installed.
I plan to install a 20 micron filter in the return fuel line just before the return flow sensor.
Questions:
1. What is the source of the debris?
2. Are the metallic debris a symptom of a serious engine condition?
Thanks

I guess you have to think what is between where this debris showed uo and the output of the engine-mounted filter, and that pretty much comes down the injector pump doesn't it? The added filter is a good interim fix for the flow meter, but.....

The shape of the metal reminds me of shards occasionally spun off from threaded fittings. Is there by any chance threaded fittings between the injector pump and the sensor?

Ken

No answer, and not to hijack the thread, but any one else use these?
Flows can out of business

Floscan’s website is still active and shows “under new management. Have you heard something else? (Sorry for the hijack).

I think that Floscan went out of business but someone took it over and opened it back up, at least that was my understanding.

Congratulations on a well detailed post.

Ferrous metal thread slivers are unlikely to have been circulating in your engine for any time so my first thought is that they came from the flowscan fitting itself. That IMO would be the likely source of new ferrous slivers.

Experience has taught me to disassemble and inspect all new parts, if possible, to look for metal shavings not properly cleaned in manufacturing. Sad but true that IMO many later failures are caused by sloppy initial work.

If engine has a Lucas CAV pump, all the guts of that pump are lubed with fuel. Any wear products created internally are in the fuel too. So no surprise some of them come out with the return fuel. Could be thread cuttings, could just be normal wear products. A small fine mesh filter on the inlet to the flow meter may make sense.

I would not worry too much about the existence of these particles, all machines create some. Provided the engine is running well.

Ski, don't you mean a Simms pump?
Gale warning, heavy rain, no boat stuff, no golfing. Rats, all there is to do today is nit-pick. Sigh.

As said it seems to be part of a thread maybe. Does not seem to be something to worry about at this stage IMO. I would put your filter inline, buy a few extras, and then after operating for a while cut one open to inspect. The type of debris that usually gets me worried is lots of small sparkly stuff that looks like you just panned for gold or dropped a glitter container...lol. The inline filter inspection after some hours of operation should reveal if that is happening.

I agree that wear particles usually dont look like thread shavings.

kchace said:

The shape of the metal reminds me of shards occasionally spun off from threaded fittings. Is there by any chance threaded fittings between the injector pump and the sensor?

Ken

Click to expand...

The attached photos show the return fuel line transition from the metal tubes that carry unused fuel to the rubber hose that returns the fuel to the tanks. More than one threaded fitting exists in this fuel return line
Thanks

bayview said:

Congratulations on a well detailed post.

Ferrous metal thread slivers are unlikely to have been circulating in your engine for any time so my first thought is that they came from the flowscan fitting itself. That IMO would be the likely source of new ferrous slivers.

Experience has taught me to disassemble and inspect all new parts, if possible, to look for metal shavings not properly cleaned in manufacturing. Sad but true that IMO many later failures are caused by sloppy initial work.

Click to expand...

bayview: The Optio sensor is constructed of non-metallic components except for the 2 magnets located in the posts of one of the gears. The hose barbs are constructed from aluminum. The debris that appears to be slivers from a fuel line fitting are ferrous.
Thanks

Ski in NC said:

If engine has a Lucas CAV pump, all the guts of that pump are lubed with fuel. Any wear products created internally are in the fuel too. So no surprise some of them come out with the return fuel. Could be thread cuttings, could just be normal wear products. A small fine mesh filter on the inlet to the flow meter may make sense.

I would not worry too much about the existence of these particles, all machines create some. Provided the engine is running well.

Click to expand...

Ski in NC: The fuel pump is a Lucas CAV pump. Would you expect the 2 larger debris particles shown in the first and third photos to pass through the injectors and then into the return fuel line?
Thanks

Panacea123 said:

No answer, and not to hijack the thread, but any one else use these?
Flows can out of business

Click to expand...

Panacea123: The Optio fuel flow sensors are manufactured by Interactio in BC, Canada. The sensors were reviewed by Panbo.com last year.
Contact info:
David Burton
dburton@interactio.co
Thanks

DLETF,
It seems to me to be best to follow Ski's advice. Install the proposed filter before the return sensor, and after a few hours of operation (say 50?) change it out and cut it open and examine the interior for particles. If there appears to be a lot of particles, or one's as described above indicating wear, then maybe further investigation (here, with Tony Athens, Cummins, etc.) may be in order.

This as long as the engine is running well now. JMHO.
PS> What kind of fuel numbers were you getting?