Flowscans problems

[Brian Degulis]

Hello all I've installed a set of Flowscans on our boat 61' MY with 1271TIs. After completing the installation I can't get them to read properly. The readings are un steady and after idling for a while they climb up. If I go back up to 1000 or so RPM and leave it there a few minutes the readings will get acurate and reasonably steady then If I idle down after 5 minutes the readings go up and become un steady again. I've gone thru the entire fuel system and there are no vacum leaks. I've put a section of clear hose int the line between the forward fuel sensor and the lift pump and there are no air bubbles visable. As far as I can tell I'm within all the instalations guidlines I changed several things try to solve the problem so I believe at this point my instaltion sould be ideal unless I'm missing something? I've been in touch with the techs at flow scan sent photos and emails but as of right now they don't know what the problem is. Both engines act exactly the same so I'm thinking both flowscan units have the same problem (very unlikely) I've missed something but at this point I can't imagine what it is or there is something wrong with the interface of these units and this engine and fuel system?

As Of right now I'm really at a loss I've spent a lot of time by passing diffrent parts of the fuel system trying to nail it down but I'm getting no where. I have not yet taken the boat out all my findings are at the dock under no load So sugestions experiences would be apreciated.

Brian

 

[captddis]

Brian, run the boat out!

 

[Brian Degulis]

Yeah I know dave I'm going to do that next and then if I'm still having problems (I'm pretty sure I will be) then I'll put them in diagnostic mode record everything and send it to flowscan.

Brian

 

[Boss Lady]

Flowscans rely on the fuel flow meter and these are sized for the appropriate range of fuel consumption for the HP rating. They will be less accurate at idle speed fuel flows. Top off your tanks and go run the boat at normal cruising speeds. You will find them to be very accurate. Under no load conditions you will barely flow enough fuel to tickle the flow meters. Idling in gear will increase the flow demand to read accurately. Out of gear loads will give erratic readings. The flow meters for your application are large in comparison to the flow at no load consumption. Smaller flow meters are more accurate at low flow conditions. Go put the engines in gear and see if they become steady.

 

[Mike36c]

Something to think about... My little cummins 6BT's flow 60GPH @ rated RPM. With no load consumption is nil and the feed/return sensors have a tough time calculating. Go run it.

 

[Boss Lady]

Detroits return a lot of fuel to the tank (excess fuel keeps the injectors cool) and require a second flow meter to measure and compare the input flow to the output and then calculate consuption. The are only accurate at a given flow range. Without look it up, I would guess it to be somewhere around 2-3 gallons per hour and greater on this size system.

 

[Skip]

One thought-did you calirate them correctly? If not, they could be on the wrong schedule. I had a problem getting the digital RPM guage to math the tachs at the lower station.

 

[Brian Degulis]

Thanks for the replies what your saying makes sense I'm just not sure how you guys are defining in acurate or fluctuating readings. So give me an idea of what your seeing on start up then idle and then say 1200 RPM all in neutral (no load).

Brian

 

[Mike36c]

My gph readings dance around .5 to 2.5 each at no load idle. Once underway they settle down to around 1.2 gph each @ 1000rpms (330hp 6BT's). At cruise they hold a value fairly steady but never are the numbers rock solid, could just be my application. Remember that in large sea conditions the governor will vary fuel flow which will cause the numbers to dance somewhat. What's interesting is that the total fuel use at fill up is accurate despite the fluctuations. ANY air entering the system causes havoc with the sensors.

 

[Brian Degulis]

Thanks Mike I've got wildly fluctuating readings if the engines sit and idle with or without load the GPH will slowly rise to 4-8 GPH at higher RPMs there are steadier. There is no air I've been talking to the techs at Flowscan and they are recomending aditional Dampers. The older kits had remote dampers mounted high on the new kits these were eliminated so hopefully adding them will do the trick.

Brian

 

[Mike36c]

Maybe you're onto something... My system came with two pulsation dampers per sensor and since the Cummins flow such a high rate of fuel (return) I had to purchase the larger flowscan sensors, we probably have the same set-up. Good luck.

 

[captddis]

All the Detroit systems I installed had 4 pulsation dampers per engine

 

[Brian Degulis]

All the Detroit systems I installed had 4 pulsation dampers per engine

Hi Dave Yes from what I understand the old kits had a homogenizer and unit mounted pulsation damper and also required a remote mounted pulsation damper mounted above the fuel pump on the forward flow.The return flow had a unit mounted pulsation damper plus a remote mounted. For some reason if you buy a kit (speced for DD) Flowscan is now omitting the remote mounted dampers so hopefully that is my problem.

Brian

 

[doc g]

Brian,
I will check mine this weekend but I think mine have 2 dampeners on the inlet side and two on the outlet side . I have found with mine that if the filters need to be changed (both primary and secondary) the Flowscans will read errratically especially at lower fuel rates. The Flowscans will let me know before the vacuum gauges will. I've got mine dialed in so that they read about 10 % higher for reserve . And, yes they do bounce around a bit at no load idle but smooth out at 950 -1000 rpms . Hope this helps. ......Pat

 

[Brian Degulis]

Looks like I can put an end to my Flowscan adventure. After searching for vacuum leaks changing fuel lines re sealing 4 racor filters adding 4 additional pulsation dampers etc. etc. The problem turned out to be the wrong orifice in the forward fuel sensors. The original kit was a D orifice in the forward sensor and a C in the return sensors changing the forwards to Cs solved the problem. It would have been a lot better if these things were set up that way to begin with I probably have around 40 hours labor after the installation trying to solve the problem believing it was an installation issue. In flowscans defense they say the original configuration has always worked on 1271s in the past. They're tech's always answered the phone or called back and seamed genuinely interested in solving the problem. During the process they sent 4 pulsation dampers 2 replacement gauges then 2 replacement sensors with 2 more replacement gauges all at no cost. They could have asked for the original parts back and they could have simply changed out the orifices in the original sensors and re calibrated the original gauges. Instead to save time they just sent new stuff at no charge without getting the original stuff back.

My advice to anyone thinking about installing these things is first draw up a diagram of your fuel system include all the heights of the components and the lengths and sizes of the lines. Have a discussion with the tech's (not the sales people) at flowscan and email them the diagrams. Let them know how you use your boat weather you are more interested in low RPM accuracy or high cause they can focus they're calibration procedure on the flow range at your RPM. When installing lose the normal neat thinking like using elbows instead of bending the line think smooth flowing curves like a good looking woman and correct any potential vacuum leaks. Use the Flartite seals on all SAE or JIC flare connections and go against they're advice and use Teflon tape on all NPT fittings just start it a few threads back to avoid any pieces breaking off and getting into the system.

Brian