Does Flow Scan meter inhibit fuel flow on outboard ?

[bgreene]

Experienced Evinrude dealer says a flow scan meter inhibits fuel flow to outboard, and even causes fuel to bubble...........

My 05' Rude 200hp DFI seems to be great on fuel........as when cruising at 25mph / 3,700 rpm.
Would like to know exactly how many gallons per hr it's burning, but I'm concerned about this fuel restriction issue.

What's the deal ?

[prockvoan]

I have flow scan meters on twin optimaxes with no problems.I also have inline (can type) fuel filters which Merc states not to use,but I havn't had any problems with that.

[SeaJay]

Fuel flow meters are one of the most favorite toys out there. Even if true ain't none of those people willing to believe you, and most will argue the point strongly.

[marinerjoe]

I had FloScans on my twin 225 HP FICHTs. There was NO restriction in flow, and operation was outstanding.

Sounds to me like your "experienced dealer" has little experience with a proper installation of these super instruments.

I took out my two Evindure tachs and put in one hole the twinscan dual fuel flow meters, and the other hole had the twinscan dual tachs. Worked great!

Joe

[thresher15]

I had Flo Scan on a 2001 225 Evinrude Ficht with no problems and I have Lowrance LMF 400 now (98 150 johnson)and I have never had any problems. I highly recomend a fuel flow meter; once you have one you wonder how you did without it. It's like an addiction always looking to see what your fuel burn is

[1NO REGRETS]

Got em, use em, no restrictions to em..........................!These days there are more with em than wthout em.Find a new experienced what ever you call him.He's not touching my stuff.

[john3976]

Just make sure you intall them pointing up and not on their side. From what I have read that is where the air bubble problem comes in when they are sideways rather then pointing up to allow any air to escape from the sensor, that is from the manufacture by the way.

[ABoater]

No issues with mine.

I've had them on both O/B's and I/O's.

[kerno]

Since Yamaha sells them as a part of their fuel management system and they come in various sizes for various horsepower ratings, I'd have to say the dealer is off base.

[John_Madison CT]

We should keep a log of things the "mechanic said". Sometimes I wonder where these guys got their training.

[DreamWeaver21]

I installed a Navman and it says in the installation material that it does create a slight restriction (.9 inches mercury or something like that.) I would think they all have to slighty.

[jethro1]

Yes, a fuel flow transmitter added to a fuel supply system inhibits the flow of fuel. It is simple physics.

Every transducer, every fitting, every filter, every bit of the hose and every turn that it makes, the anti-siphon valve or shut off valve, etc etc all restrict the flow of fuel to the motor. The key is to make sure that the total of all of the restrictions do not adversely affect the amount of fuel that makes it way to the fuel pump.

The only way to know for sure is to install a vacuum gauge in the fuel line at the inlet to the fuel pump. Then, with the motor running at high power measure the amount of vacuum (restriction) to see if it is within specs or not. Too much vacuum and you are overworking the pump, at best. At the worst you can cause the engine to run lean which is not good.

[timo14]

I agree with Jethro... definately cause restriction. It may be very slight, but it could be enough to cause problems. When I installed mine, i had to add about 18" of fuel line to get the sensor between my racor and side of the splashwell. When running WOT, i kept setting off the fuel flow alarm. Disconnected the sensor and put a barb-barb fitting in where the splice in the lines was... no more alarm. I'm going to have to pull out my anti-siphon valve and/or my inline fuel filter (the one that is on the engine) to get my fuel pressure up.

[timing]

Good comments from Jethro.

Orig ? - Restriction and bubbles likely true, but enough to cause issue?

If your fuel delivery system is boarderline to start with, then it's possible adding the fuel flow sensor could put it over the edge and result in issues.

Jethro's vacuum reference is a precise way to tell for sure. A basic check might be comparing WOT pre and post install. I installed the Yam FMM on my current boat, no difference in WOT performance.

I mention fuel delivery system because my prior boat without a FMM had issues at WOT,
couldn't run WOT for even a full minute before stalling. Suspicious a FMM sensor would have made things worse.

btw - This my first FMM, I'm hooked, gotta have it going forward.

[Eastbound]

I was wondering this same thing. I just bought a 28 McKee and have 250 DI's on it. My port motor has been giving me problems from day one, but I expected these problems because of the previous owners lack of use. I have flow meters on the boat, and the one going to the port motor is not reading the flow. That's also the motor that takes about a minute to start, and cuts off whenever you shift from forward to reverse in a steady motion.

I was told by a friend to pull the fuel lines off, and take my air compressor to it, and blow the trash out. He also told me to have someone watch the flow meter, and you should see it reading the amount of air flow. Is this true?? I was going to start this project this afternoon if the rain stops.

[socuban]

ABoater - 10/23/2007 5:47 PM

No issues with mine.

I've had them on both O/B's and I/O's.

Same here I currently have them installed on twin Yammi 200s and my Grady White Gulfstream gets up to 52 mph