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Yamaha Fuel Management Gauge?

Old 11-15-2013, 06:26 AM
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Default Yamaha Fuel Management Gauge?

I have twin Yamaha 115 4's on my catamaran. In an effort to more fairly split costs I've attempted to used the gauge(Yamaha), however it doesn't seem very accurate.

I generally fill both 60 gallon tanks at gas stations w/ non ethanol fuel- On level ground until their 3/4 full. Tanks are equipped w/ float gauges. So, if I fill back to the same point on both tanks. A typical offshore trip the gauge will say I burned 48, but at the pump seems I only have to put in 38 to get back to 3/4 full on both side.

So, is there some way to calibrate this gauge, or am I putting too much trust in the float gauges?

Its been theorized by one of my fishing partners I should go by the Yamaha gauge since its always higher, except when he goes.

Any suggestions would be greatly appreciated
Old 11-15-2013, 07:20 AM
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Are you talking about a fuel quantity gauge or a fuel management meter? You talk of float gauges which means a quantity gauge. Then you talk of the gauge saying you burned 48 gallons which leads me to believe you are talking about a fuel management gauge. Your title is headed as the Fuel Management Gauge but it has nothing to do with a boat being level or floats!!!! I am easily confused and you have got me.

Tank quantity readings are known to be very problematic. Why, because of the crappy senders that are generally used. Even with very good quality senders, the quantity displayed on a quantity gauge can be skewed by the pitch attitude of the boat. Senders can be at the back of a long tank. As the bow rises or lowers, fuel goes back and forth and raises or lowers the float position which changes the indicated quantity. Furthermore, most needle type quantity gauges simply don't have the fidelity needed to get much closer than someone estimating tank quantities to the sixteenth of a tank.

A fuel management gauge however can usually indicate fuel used to one gallon or less. If it is not as accurate as maybe it should be, a Yamaha FMM can be calibrated to make it so.

Fill the tank to the brim. Reset the Fuel Management Meter to zero.
Reset the meter so that it indicates zero fuel used. Use the boat all day. Top off the tank upon your return. You will know exactly how much fuel you used and can share fuel costs accordingly. You will then compare fuel used according to the meter with the fuel used based on what it took to refill the tank. They should be more or less the same. If they are not, you can calibrate the fuel flow meter to be more accurate.

Once the fuel flow meter is known to be accurate you can simply use it to determine your daily fuel usage. Simply reset it to zero before heading out and then see what the indicated fuel usage is at the end of the day.
Old 11-15-2013, 07:35 AM
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Jethro1,

I guess I made my own thread confusing. I do indeed have a Yamaha fuel management gauge- It allows me to know GPH while at power, and also total gallons burned, which I reset each day.

My cat is very sensitive to weight, and less efficient when I carry full fuel tanks. Even after a long offshore run I'm never below even quarter tanks. I have 2 separate fuel level gauges- I ASSume are on float senders. So when I refill after a day of fishing I only refill to 3/4 full on each tank based on the individual tank gauges, and then base my total amount burned off that. But if I compare to the Yamaha's burned amount its usually higher by 20% approximately.

Hope that made sense.
Old 11-15-2013, 08:24 AM
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Originally Posted by big bass View Post
So when I refill after a day of fishing I only refill to 3/4 full on each tank based on the individual tank gauges, and then base my total amount burned off that.
By using this method, you have introduced multiple sources for error, and you will never be able to make a meaningful comparison with your Yamaha fuel management gauge. You must do as Jethro says, and fill your tanks completely until the pump shuts off or fuel spills out the vent. You cannot rely on your fuel tank gauges reading "full" for purposes of this comparison test, and trying to do so at an indicated "3/4 full" is even more imprecise.
Old 11-15-2013, 08:58 AM
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OK, I will try the more sensible "full tank" method next time and refill for a much more accurate comparison. Even though that hurts my efficiency.

So, for conversations sake if the difference is still 20% how shall I proceed?
Old 11-15-2013, 09:30 AM
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Originally Posted by big bass View Post
OK, I will try the more sensible "full tank" method next time and refill for a much more accurate comparison. Even though that hurts my efficiency.

So, for conversations sake if the difference is still 20% how shall I proceed?
Differences between what?

As Pez notes, if you try to compare a typical needle type fuel quantity gauge with a fuel management meter then you can't get there from here. You are comparing apples to oranges and that won't work.

If you want a fuel quantity gauge to be accurate, as accurate as is your fuel management meter, then you will need to get a digital fuel quantity gauge with a capacitance type fuel probe.

Why not leave the quantity gauge alone and just go by the fuel meter for your purposes? Once you know that the fuel management meter is calibrated and accurate, why not just use what it reports as the fuel burned for any particular trip? Then divide that by however many people are sharing fuel costs.
Old 11-15-2013, 09:35 AM
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As Jethro said, you may calibrate your Yamaha gauge. You do not need to do this after your 1st trip after filling up, especially if the trip is a short one and burns little fuel. I would run the tanks down to the lowest level you are comfortable with, say 1/4 tank, before you refill and make your comparison/calibration. I would repeat the entire procedure more than once to establish a good level of confidence in the calibration of the Yamaha gauge. Good luck with it.
Old 11-15-2013, 10:39 AM
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Thank you both for the advice!!
Old 11-15-2013, 11:28 AM
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Jethro1

I missed your response-sorry.

Difference between what?

By that statement I meant if I fill the tanks completely before an offshore run, and upon return the Yamaha gauge shows I burned 50 gallons, yet after refilling completely again and the fuel pumps reflect
only 40 gallons then I've got a "difference".
Old 11-15-2013, 11:53 AM
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Originally Posted by big bass View Post
Jethro1

I missed your response-sorry.

Difference between what?

By that statement I meant if I fill the tanks completely before an offshore run, and upon return the Yamaha gauge shows I burned 50 gallons, yet after refilling completely again and the fuel pumps reflect
only 40 gallons then I've got a "difference".
Got it.

You would go to the back of the gauge and make some adjustments that will input a correction factor into the gauge. Ideally, the gauge can be adjusted to the point that it is spot on. You actually used 50 gallons, and put this much into the tank to top it off, and guess what, the gauge indicates that 50 gallons were used.
Old 11-15-2013, 12:41 PM
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My accuracy is an obvious "to be determined". The part I'm going to struggle with is I don't need 120 gallons to go 50-60 miles offshore. Even if I grow to trust/rely on the monitoring gauge I can't under fill the tanks and guess which side has burned more. The boat may become lob sided on weight...lol.
Old 11-15-2013, 09:10 PM
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As sidenote, how do you calibrate the Yamaha FMG?

Tony
Old 11-16-2013, 07:44 AM
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Originally Posted by big bass View Post
My accuracy is an obvious "to be determined". The part I'm going to struggle with is I don't need 120 gallons to go 50-60 miles offshore. Even if I grow to trust/rely on the monitoring gauge I can't under fill the tanks and guess which side has burned more. The boat may become lob sided on weight...lol.
That is why it is good to have fuel quantity gauges. Two in your case. One for each tank. Then you will see the fuel quantity in each tank.

Fuel quantity can be cross checked against a fuel management gauge to determine if both are more or less in agreement with each other. They should be. If not, time out to investigate what in the hell is going on.

First get your fuel quantity gauges in good working order. There are fuel quantity gauges, that when coupled with solid state senders, will be about as accurate as the fuel flow meter. Maybe you need to consider installing a different type of quantity gauges.

You have 60 gallon tanks but you only want to fill them to the 3/4 mark which is 45 gallons. With a digital fuel gauge, or an analog gauge with a good sender, you will see this on the gauge and you fill them accordingly.

You also have the Yamaha fuel management meter installed. You reset it so that it displays zero fuel used. You go and use the boat all day. The FMM indicates that a total of 40 gallons have been used. Back on shore you refill each of your tanks such that the quantity gauge reads at the 3/4 mark. I am betting that the fuel added to the tanks will be roughly 40 gallons. If you had digital display quantity gauges installed you would fill each tank until each gauge read 45 gallons (the 3/4 tank starting point).

You just need the right stuff installed to get the results that you want.
Old 11-16-2013, 07:48 AM
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Originally Posted by tonybanco View Post
As sidenote, how do you calibrate the Yamaha FMG?

Tony
Old 11-16-2013, 09:53 AM
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Originally Posted by jethro1 View Post
That is why it is good to have fuel quantity gauges. Two in your case. One for each tank. Then you will see the fuel quantity in each tank.

Fuel quantity can be cross checked against a fuel management gauge to determine if both are more or less in agreement with each other. They should be. If not, time out to investigate what in the hell is going on.

First get your fuel quantity gauges in good working order. There are fuel quantity gauges, that when coupled with solid state senders, will be about as accurate as the fuel flow meter. Maybe you need to consider installing a different type of quantity gauges.

You have 60 gallon tanks but you only want to fill them to the 3/4 mark which is 45 gallons. With a digital fuel gauge, or an analog gauge with a good sender, you will see this on the gauge and you fill them accordingly.

You also have the Yamaha fuel management meter installed. You reset it so that it displays zero fuel used. You go and use the boat all day. The FMM indicates that a total of 40 gallons have been used. Back on shore you refill each of your tanks such that the quantity gauge reads at the 3/4 mark. I am betting that the fuel added to the tanks will be roughly 40 gallons. If you had digital display quantity gauges installed you would fill each tank until each gauge read 45 gallons (the 3/4 tank starting point).

You just need the right stuff installed to get the results that you want.

Throw up a few links or model #s of what you are describing at your leisure and I will be greatly appreciative.
Old 11-16-2013, 10:19 AM
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Senders (two) at $62.00 each from

http://www.centroidproducts.com/


Quantity gauge at $118.00 from

http://www.cruzpro.com/f60.html

Two senders required. One for each tank.

One or two gauges required. If just one gauge is installed you will also need a two way toggle switch so that the one gauge can be connected to either one tank or the other.

The gauge might be available at a discount from one of the USA distributors listed at the manufacturer's website.
Old 11-16-2013, 01:33 PM
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Originally Posted by jethro1 View Post

Thanks!
Old 11-17-2013, 05:15 AM
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Originally Posted by jethro1 View Post
Senders (two) at $62.00 each from

http://www.centroidproducts.com/


Quantity gauge at $118.00 from

http://www.cruzpro.com/f60.html

Two senders required. One for each tank.

One or two gauges required. If just one gauge is installed you will also need a two way toggle switch so that the one gauge can be connected to either one tank or the other.

The gauge might be available at a discount from one of the USA distributors listed at the manufacturer's website.

I would prefer two gauges- that's what I'm accustomed to.

Just curious, how long have these type products been available? Would this be a DIY project, or is calibration involved?

This would certainly be worth $400 to see who has been getting the raw end of the fuel bill.

Thanks again! Great info.
Old 11-17-2013, 06:45 AM
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Originally Posted by big bass View Post
I would prefer two gauges- that's what I'm accustomed to.

Just curious, how long have these type products been available? Would this be a DIY project, or is calibration involved?

This would certainly be worth $400 to see who has been getting the raw end of the fuel bill.

Thanks again! Great info.
I can't say how long the gauge has been available but I have had mine for well over ten years. The capacitance type probe is the same.

it is a DIY project depending upon one's self.

Calibration is involved but it is simple. There are 16 calibration points on the gauge. Divide the fuel tank capacity by 16. 16 into 60 in your case which is 3.75.

Start with the tank empty. Add 3.75 gallons. Enter this amount in step one. Add another 3.75 gallons. Enter this amount in step 2. Repeat the process until you are done. The gauge will now indicate fuel in increments of one gallon. Maybe less, I can't remember. You only do this one time.

Let's say the tank shows 10 gallons remaining. You add ten gallons. The gauge will now indicate 20 gallons as being available.

I would not own a boat without one being installed.

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