Logo
FULL SITE MENU

Gauges stopped working

B

baxter1829

New member
I noticed my fuel gauge did not work when I put my boat in the water and started it up this spring. (2005 22 foot Aqua Patio with 90 hp Yamaha). Gauge on top of the tank works fine and shows tank is half full. The analog gauge is on the console. When I turned the ignition to the "on" position all gauges activate but the fuel gauge needle does move a bit but doesn't go past the "E" mark. Removed the panel and popped out the gauge to try tapping but no go. Then I removed wiring from the back stupidly forgetting to turn off battery switch. I must've touched something causing a short because when I connected everything back up none of my instruments will work. (Grrr). Now I have 2 problems (one of my own making). There are circuit breakers on the console beside the switches for Acc, Radio, lights but none seem to be tripped. I believe I've blown a fuse somewhere but have been unable to locate it. Any help would be much appreciated!
 
I'm not that familiar with the Yamaha 90, but on many engines there will be a fuse for the instrument signals, so check those fuses on the engine first. If nothing amiss there, then you need to go on a rabbit hunt. First, make sure you have 12V power coming to your key switch. Then when you turn on the key switch make sure you have power going to the appropriate breaker and then on to your gauges.

I don't want to insult you, but are you sure what you are calling breakers are really breakers and not just switches that are fused? Sometimes what looks like a breaker is really just a fused switch and the fuse will be beside or behind the switch.

As for the gas gauge, you will likely need to remove the sending unit from the fuel tank and test it. Typically it is accessible through a hatch on your deck and will have six screws holding it in place. Generally, there are two types of senders. One type has a float on an arm and activates a simple rheostat up and down. The other type has a float collar at also operates a rheostat in the same manner. First make sure that the arm or collar operate freely and is not "fuel logged." Then attach an ohmmeter to the ground and the signal wires coming out of the top. As you move the float up and down, you should see a smooth change in resistance. If not it needs to be replaced. If you get the smooth resistance, then you have a wiring problem between the sender and the gauge, or a gauge problem. To find out which, disconnect the signal wire on the gauge and hook your ohmmeter up to that with the other lead to ground. Have someone activate the float up and down and see if you get that same smooth change in resistance. If not, you have a wiring problem. If so, your gauge is bad.

When you replace the sending unit, make sure you use a new gasket or at least make sure that the old gasket is sealed completely.
 
Thanks CHawk! I will start the rabbit hunt. You are probably right about what I called breakers being fused switches. 4 switches on the console for ACC, radio, lights and one other ACC and below each switch is a little breaker type unit so yes- agreed. Motor still starts fine, lights, radio and Garmin all work too. Tach, speedometer, voltage and fuel gauges all do not work after my bonehead move so they must be on one circuit with the fuse somewhere. I'll start at the engine as you suggest. Then, to tackle the fuel gauge issue... And no- you cannot insult me- I have very basic understanding of house wiring etc but very limited DC experience so stating the obvious will only help me! Thanks again!
 
OK. Located blown fuse under the console and replaced. Instruments working fine again. My fuel tank has a mechanical gauge on top and what I'm guessing is the sender unit attached to it with two leads coming off and going up to the gauge on the console. Mechanical gauge on tank works fine (added fuel to see if it shows it and it does). Needle on analog gauge on console is at the very bottom when switch is off. When switch is on needle jumps to the 'E' on the gauge and stays there even after I added fuel. From what you've told me it's either the sending unit or the gauge itself (or wiring but I'm hoping that's not the case for now). I guess there is no way of testing the gauge without removing the sending unit from the tank?? I'd rather not take off the sending unit unless I really have to (call me chicken).
 
I think that the only way to test it definitively is to remove it.

Having said that, boat fuel tank senders are notoriously inaccurate. If you want accuracy, you should install a fuel flow meter unless that Yamaha has one built in. On my Honda 225, I use the internal fuel flow meter exclusively to tell me how much fuel I have burned. On a 100 gallon fill up, it has never been off more than 2.5 gallons +/-.
 
Success! I decided to try to test by disconnecting the lead wires at the sender unit on top of the tank (easy access). I connected a dimmer switch to the leads going to the analog gauge thinking that if the gauge was working I should see it move when I turned from off to full on and it did so the problem had to be the sending unit. I noticed the top of the sending unit had 6 screws into the top of the tank but there were 2 small screws inside that so I took them off and voila! The sending unit came off but the tank was still sealed. The sender is encased in plastic but there is a magnet in the bottom which sits on a metallic base attached to the top of the tank. Noticed the metal looked somewhat dirty/ dusty so cleaned it off really well and replaced sender unit. Now works fine! Such a simple thing but your point about accuracy (or lack of) is dead on. The gauge on the tank reads 3/4 but the console gauge reads 1/2. I noticed the discrepancy before but I can live with it. Thanks again for your help!! Saved me a lot of time and potential $$ for a problem that was not too hard to fix!!!
 
Back
Top