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TOPIC: Lowrance Fuel flow results

Lowrance Fuel flow results 17 Sep 2007 13:40 #1

  • davidwigler
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I finally completed installation of the 5200C GPS/plotter and LMF 400 with twin fuel flow meters. They have not been calibrated, but the best cruise speed seems to be 17.3 statute mph at 1.6 mpg (total) at 3,200 rpm. This is with 1/2 fuel and two adults. Does this sound about right?

The stbd engine burns about twice as much fuel at idle than the port, but they burn virtually the same amount at cruise. Does this mean the stbd carb is set too lean?

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Lowrance Fuel flow results 17 Sep 2007 15:11 #2

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The stbd engine burns about twice as much fuel at idle than the port, but they burn virtually the same amount at cruise. Does this mean the stbd carb is set too lean?

This would possibly indicate that the Stbd carburetor idle circuit is "Rich", not lean. A simple adjustment may cure this. Note that adjusting idle fuel/air mixture will/should have no effect on higher RPM operation. Best to do this while using a vacuum guage. Adjust for the highest vacuum. Re-adjust idle RPM.
You may also have a higher fuel float level in this carburetor that requires adjustment..... of which may not be for the Do-it-your-selfer.

Hope that helps.

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Rick E. Portland, Oregon
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Lowrance Fuel flow results 17 Sep 2007 15:24 #3

  • RobertSchommer
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I think that's just excellent fuel economy for a gas-powered 38' motoryacht.

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Lowrance Fuel flow results 17 Sep 2007 16:39 #4

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I am thinking about getting that gauge myself,,,,,was it hard to install?and what components did you order for it?Just was wondering if I can do it myself or should I have a pro do it.:D

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Lowrance Fuel flow results 17 Sep 2007 17:22 #5

  • Knotheadcharters
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David,
I purchased the Lowrance 7600 global map earlier this year and have been wanting to add the fuel sensors myself . I am wondering if I have enough room in my stove pipe in order to get the backbone to the bridge, as this is where the chartplotter is located. Did you have anyproblems with this or do you run from the lower helm.

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Lowrance Fuel flow results 17 Sep 2007 18:37 #6

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The installation is pretty easy if you are handy. The problem is getting the right parts, as Lowrance's website is inadequate. Their customer support people are helpful, but plan to sit on hold for two hours before you get a human. Boat-fix has good prices on the major components, but has poor availability on the connecting parts. I waited for about two months for an expansion kit from Boat-fix before giving up. This email address is being protected from spambots. You need JavaScript enabled to view it. has the connecting parts, but make sure you order the right ones. I had to make two returns before finally getting all the right parts.

I installed the LMF 400 and 5200C both on the bridge. The LMF 400 gauge comes with one EP-10 and a network power cable with a 120 ohm terminator. Boat-fix has the separate EP-10, which comes with a second T connector and (as I recall) the other 120 ohm terminator. Boat-fix also has a 25 foot extension cable. I recommend using two extension cables screwed together in the lower helm. that way, if you want to add something later to the network at the lower helm, all you have to do is insert a new T connector.

The problem I had was connecting the 5200C GPS to the LMF 400. The LMF and the EP-10s use blue connectors, and the GPS uses red connectors. You have to buy "adapters" to put the two together. The adapters are made with all four possible combinations of male/female and red/blue (I learned after ordering the wrong ones).

Lowrance asked me whether I wanted to use the Blue or Red connectors for my network. I chose blue because I already had most of the T connectors, the network power connector and the extension cables from Boat-fix; but I learned after finally getting all the parts together that the red connectors are better. The red fittings screw together more soundly and are smaller for fishing through the stove pipe. The part number for the adapters I ended up with is 127-05. You need two adapters, one for the chart plotter and one for the GPS antenna. If you go with the red fittings, you will need two also (for the LMF and the EP-10s); the part number may be different and you will also need a red 120 ohm terminator.

It sounds complicated but once the parts are all assembled the installation is pretty easy.

Chris, see my next post about the stove-pipe.

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Lowrance Fuel flow results 17 Sep 2007 19:25 #7

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David, the 1.6mpg at 17mph sounds a little high compared to my numbers. Before you make your carb adjustments perhaps you should perform the calibration runs with a known fuel quantity.

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Lowrance Fuel flow results 17 Sep 2007 20:22 #8

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Mike,

I thought it might be too good also. I'll do the calibration and check again.

Do you still have the fuel economy performance chart you prepared with your 351s? I would like to see it again, as well as your current one.

Also, did you see my post about the shaft packing size? Is it 1/4 inch?

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Lowrance Fuel flow results 18 Sep 2007 02:02 #9

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davidwigler;69496 wrote: Mike,

I thought it might be too good also. I'll do the calibration and check again.

Do you still have the fuel economy performance chart you prepared with your 351s? I would like to see it again, as well as your current one.

Also, did you see my post about the shaft packing size? Is it 1/4 inch?


Yup the packing is 1/4" David. You need 15" per shaft.

Here are the performance numbers from the new VPs. I'll have to get the other data out of my logs on board.

1300 RPM. SOG 8.0 MPH. 1.58 MPG
2150 RPM. SOG 12.9 MPH. 0.92 MPG
2200 RPM. SOG 13.5 MPH. 0.90 MPG
2500 RPM. SOG 17.6 MPH. 0.92 MPG
2650 RPM. SOG 19.2 MPH. 0.89 MPG
2700 RPM. SOG 19.9 MPH. 0.92 MPG
2900 RPM. SOG 22.2 MPH. 0.92 MPG
3000 RPM SOG 22.5 MPH. 0.85 MPG
3200 RPM. SOG 24.6 MPH. 0.81 MPG
3500 RPM. SOG 26.9. MPH. 0.74 MPG
3850 RPM SOG 29.5 MPH. 0.65 MPG
4000 RPM SOG 30.3 MPH. 0.61 MPG

redline is 4600 RPM

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Whiskywizard
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Life moves pretty fast. If you don't stop and look around once in a while you could miss it.
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Lowrance Fuel flow results 18 Sep 2007 14:56 #10

  • Knotheadcharters
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I am suprized that the cables on the fuel sensors are only 10 feet? Just another way to get us to spend more money and have connection points that can fail. I have the blue connectors and I will be ordering from Boaters World today.

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