Gas Gauge Issue

[raymondlet]

Same here. Annoying as heck. Previous boat never had this condition.

[thozguys]

After getting some great info from the previous posts here is what I am planning on doing to fix the issue. I have a multi-finction display, Garmin 4208, that has the ability to connect to the Yamaha electrics via a NMEA cable from Lowrance. The motor will supply all the correct fuel flow information along with other critical information about the motor. I have ordered the parts to build the NMEA network and all interface cables. I should then be able to get the following info

Engine Oil Pressure : Pa

Engine Oil Temp : Deg K

Engine Temp : Deg K

Alternator Potential : VDC

Fuel Rate : cu-m/hr

Total Engine Hours : hrs

Fuel Pressure : Pa

These should also add another layer of safety since I am planning on doing some 30 - 40 mile trips to the channel islands located in my neck of the woods.

[katfish]

Thozguys,
I also have wondered what's up with my gas gauge in my 2008 215. I am in the same boat as you, excuse me, as I've made several trips out to the Channel Islands and sorta play a guessing game. As I've become more accustomed to my boat, I know that my 150 Honda uses approx. 1/4 or less tank out and back to Anacapa and the Gap, but it depends on conditions. As you know, most of the time coming back in the afternoon can be dicey in 4-6 ft. with 15kts. There's no way to get an accurate reading on fuel with the standard gage. I really appreciate all your posts and I'm going to look into a digital gage and seeing if my Garmin/GPS can link with my engine. BTW, last time out, 2 weeks ago, we came back in fairly flat conditions running wide open and made it back in 35-40 minutes. That was fun. Where do you like to fish at the Islands, as I'd like to start exploring more ground?
Steve

[tupperware]

My gas jumps back and forth too. I think its an electrical problem.

[Genelie]

Just my 2 cents.....Since the guage is mechanical it will always do the bouncing after she has burned at least a 1/4 tank....when you stop moving it is then, when you can tell what you have left in the tank. So it normal...only a digital can help you, or like others have said by a flow scan...It does not bother me, I never go further then what my boat allows, based on weather & sea conditions.

[tupperware]

No, mine is electrical because it still did it when it was on the trailer with the motor in the water.

[pamarine]

Unless you have a digital fuel gauge, your gauge is electro-mechanical. The needle is attached to a small winding that is attached to the sender in the tank. The sender is comprised of an arm with a float attached to it on one end and a variable-resistor on the other. As the arm moves up, the resistance in the sender is lowered, allowing more current to flow to the gauge. This in turn powers the winding and causes the needle to move up. Since the only way to hole the gauge still is with an electrical current, the needle will move any time there is an external motive force on the gauge. Also, even a digital gauge will not solve the problem of a variation in tank level when bouncing, as the sender is still mechanical and is mounted into an unbaffled tank. As fuel sloshes in the tank, it makes the arm move via the float, causing a change in electrical current flowing to the guage, and thus a change in tank level reading. The ways in which digital gauges can be made to compensate for this is to be coded with an averaging algorithm that only responds to long-term changes in the electrical current supplied by the sender instead of instantaneously respoding as electro-mechanical gauges do. The only way to gaurantee a consistent accurate reading of tank level is to pair a digital guage and a electronic (i.e. capacitive-type) sender mounted in a baffled tank. Hope this helps somebody somewhere.

[thozguys]

I have finally solved my issue with the fuel gauge. Taking some advice "HighTechRedneck", I purchased a NMEA 2000 connector for the Yamaha F150. I connected the cable to the NMEA 2000 network that connects to my Garmin 4208 multi-functions GPS/Sonar/Radar. The hardest part was getting some of the native Yamaha functionality like trim position, fuel flow (GPH), tach, and voltage to read properly on Garmin. Locating the connector on the motor to connect the NMEA cable was a bit of pain, but getting the trim to read properly was the most fustrating part. I also found out that Yamaha does not send temperature information to NMEA devices as that information is considered propriatary. Everything else works great. I can now tell from the motor exactly how much fuel is being used at any point in time. The GPS unit then subtracts the amount of fuel used from the total amount of fuel that was in the tank. From what I can tell the amount of fuel remaining is very accurate.

Some may ask, why didn't you just use a NMEA 2000 fuel flow sensor. When I looked into the cost, most fuel sensors were in excess of $100, where the Yamaha connector was less than $50 and I was able to pull more information from the motor natively.

If anyone is interested I would be happy to post some pictures, with some of tips and tricks used to install the NMEA 2000 cable/network?

My thanks go out to everyone on this thread as everyone gave some great information, than in the end, helped me solve the problem. I can now cruise to some of the outer islands without worrying about the fuel level.

[tneut]

Thozguys,
Thanks for the article. I would absolutely love to see how you did it . And it makes a lot of sense to rely on the motor for fuel usage. And it might be a good reason to go ahead and upgrade my electronics.
Thanks

[thozguys]

I finally had time to document the installation.

The document is mainly for those people with Garmin or Lowrance multi-function displays as their network NMEA 2000 cables are the same. The Lowrance cables are cheaper than the Garmin cables which is why I used all Lowarance cables on my Garmin MFD. It is possible to use the same method for RayMarine & Furuno MFDs, but their network cabling is much different than the standard NMEA 2000 cabling and requires modified interface cables.

This whole project took approximately 4 hours to complete. That is including the creation of the NMEA network and running the cables from the console to rear starboard hatch where the fuel bulb and battery cables are located.