Yamaha fuel gauge question

Deadstockpomp

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-92 explorer 24

-2008 Yamaha f250

-Yamaha command link gauges (square) tach and speed/fuel

so the boats in the water, I’m catching fish already in March and besides the fact the I broke off a drill bit in my speedo pilot hole I feel like my fuel gauges are not reading properly. The boat was stored with about 3/4 in the aux tank and about 1/2 in the main or something like that, not full. I topped off at the gas station before dumping the boat and now I feel like they are both stuck on full. Occasionally they go blank but no matter what so far the bars are the same on both sides. At the mechanic my sending unit in my rear tank was re sealed due to corrosion and causing a small leak and the front one was working fine.. am I not giving the tanks a chance to lose fuel and freaking out?? Or do I have some sort of wiring issue? I disconnected the harness to the gauge that controls the fuel gauge and re plugged it to try and reset everything. I’m a little stumped and want to get this figured out. I’m a little worried simply because I’ve been running on the main tank for about 3 trips I’d say I burnt a decent amount of fuel to at least see one bar drop down. Thanks any ideas?
 

seasick

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Disconnect the pink wire at the sender and let it hang loose. Turn on the ignition and the gauge should read empty.
Now connect the pink wire to a good ground and turn on the ignition. The gauge should read full. If that is what you see, the wiring and the gauge are OK.
Next step is to check that the sender ground is good and that the tank ground is good. Just look for bad or missing grounds.
If the grounds are good, sorry to say bu the next step would be to pull the sender to check it. Let's look at the wiring first
 

Deadstockpomp

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Disconnect the pink wire at the sender and let it hang loose. Turn on the ignition and the gauge should read empty.
Now connect the pink wire to a good ground and turn on the ignition. The gauge should read full. If that is what you see, the wiring and the gauge are OK.
Next step is to check that the sender ground is good and that the tank ground is good. Just look for bad or missing grounds.
If the grounds are good, sorry to say bu the next step would be to pull the sender to check it. Let's look at the wiring first
Thanks. will be trying this out sometime this week. Bummed I have to open the deck panels again but oh well
 

Deadstockpomp

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Update: the aux tank seems to be reading accurately I changed the connections anyway. When I disconnect the connection the gas bars disappear and when I reconnect they re appear. Now for the rear tank I changed the pink connection connector cleaned the grounds off and what not and I can’t seem to get the gauge to pick up that tank on one of the columns on the Yamaha gauge. It’s sort of like the machine is only recognizing the one tank.
 

wspitler

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I don't have my Yamaha command link gauge install manual handy, but you can get it on line. The fuel gauges, like the trim gauges have to be calibrated. They are adjustable to the type sender (US, EURO, etc.) and to the number of tanks. Might check the manual and make sure it is set up for two tanks.
 

seasick

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Here is a link to the manual.

I assume you had this boat last season and the gauges worked. Is that correct? If so the setup shouldn't have changed but if not you have to redo the initialization to make sure it is configured correctly
 

wspitler

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Here is a link to the manual.

I assume you had this boat last season and the gauges worked. Is that correct? If so the setup shouldn't have changed but if not you have to redo the initialization to make sure it is configured correctly
Don't think that specific gauge 6YC existed in 2008. Could be wrong though. I think he probably has 6Y8. http://www.criboats.com/wp-content/uploads/2015/04/CommandLink-Operation-manual-Square.pdf
 

Deadstockpomp

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I’ve come to a conclusion. I grounded off the rear tank sending unit and it started to read full. Once I put power to it regularly it did not recognize the tank. The sending unit is bad. Doing the tanks probably next season so I’ll just record fuel with the ttl function for now. The tank is fragile don’t want to play with it to much and risk it leaking from the sending unit again
 

wspitler

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Easy to check the sender, disconnect and hook up an ohmeter to the leads. approx. 30 ohm = full 240 ohm = empty. Anything in between is probably good if tank is less than full.
 

seasick

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What does "put power to it" mean. Either the pink wire is grounded to test for full indication or left disconnected for empty indication. No power (hot lead) should be connected to the pink wire.

Although the resistance will show a possible open (bad sender) it may show an actual resistance in the normal range but if it reads lets say 200 ohms, that could mean the tank is just about full or it could mean that the sender is stuck at one position and always reads the same level.