1993 130hp fuel gauge vs fuel sending unit

[GLS062866]

I re-powered with a 1993 130hp. Gauges were shot so purchased a set of used digital gauges 6Y5-83500-03-00 and 6Y5-83500-A0-00. Problem is with fuel tank full gauge only reads about half full when tank is filled. I rewired the pink wire from sending unit to white wire from gauge. I guess ground is running to some spot on the tank that i can not see. The sending unit has 5 screws holding it down with an additional screw that I assume is used to ground the gauge if needed. To rule out if ground is bad I ran another ground straight to the screw on sending unit but it did not change anything. I read where some of the yamaha fuel gauges had dip switches to set if not a yamaha sending unit but this one does not appear to have switches to change. Few questions if anyone can give me some advice.

1. They would not be internal switches that I would have to take gauge apart to access would they?

2. I removed the sending unit and it checked it with ohmmeter and the resistance did change. Using the numbers on unit (8341-70-896) I can not find out who makes it to see what the spec range is suppose to be. Are they generally the same for all sending units?

3. when the key is turned on the gauge does come on and the bars go to the full position but I understand that all of them do that when first powered up with key. Is that correct? And is so I would have to assume that digital/LCD bars above 1/2 full on the scale of bars are working and not burnt out/malfunctioning. Is that a safe assumption?

4. I also removed the sending unit, grounded it and moving it by hand could not get the bars to go any higher. I could get them to drop but not go higher that 1/2 which is what it read while installed. So I took that the float mechanism was not moving up high enough out of the equation with that.

5. If I disconnect the sending unit the bars drop all the way down to empty and the fuel light starts to flash which I understand is what is suppose to happen. Then when I ground the pink wire at sending unit the gauge then goes to full. Is this the correct way to test wiring and gauges and point more toward sending unit?

6. Is it possible that the sending unit is not giving correct resistance reading even though it is changing? Or can the resistance be correct but gauge is not reading it correctly?

7. one last one please. Is it correct that they changed in 94 so if I wanted to upgrade to any newer digital gauge for after 93 I would need to get additional wiring harnesses to convert to newer gauges? Could I convert just one of them (fuel) and not have to upgrade tach to the new style? If i convert to analog then they will not be lighted correct?

thanks,
GLS

[fairdeal]

is there a black rubber plug on the back of the speedo?

[boscoe99]

I re-powered with a 1993 130hp. Gauges were shot so purchased a set of used digital gauges 6Y5-83500-03-00 and 6Y5-83500-A0-00. Problem is with fuel tank full gauge only reads about half full when tank is filled. I rewired the pink wire from sending unit to white wire from gauge. I guess ground is running to some spot on the tank that i can not see. The sending unit has 5 screws holding it down with an additional screw that I assume is used to ground the gauge if needed. To rule out if ground is bad I ran another ground straight to the screw on sending unit but it did not change anything. I read where some of the yamaha fuel gauges had dip switches to set if not a yamaha sending unit but this one does not appear to have switches to change. Few questions if anyone can give me some advice.

1. They would not be internal switches that I would have to take gauge apart to access would they? There should be switches so the speedometer can be adjusted for various sender types. Access is via a port on the back of the speedometer.

2. I removed the sending unit and it checked it with ohmmeter and the resistance did change. Using the numbers on unit (8341-70-896) I can not find out who makes it to see what the spec range is suppose to be. Are they generally the same for all sending units? Range for a USA sender type is nominally 30 - 230 ohms.

3. when the key is turned on the gauge does come on and the bars go to the full position but I understand that all of them do that when first powered up with key. Is that correct? Yes. And is so I would have to assume that digital/LCD bars above 1/2 full on the scale of bars are working and not burnt out/malfunctioning. Is that a safe assumption? Yes.

4. I also removed the sending unit, grounded it and moving it by hand could not get the bars to go any higher. I could get them to drop but not go higher that 1/2 which is what it read while installed. So I took that the float mechanism was not moving up high enough out of the equation with that.

5. If I disconnect the sending unit the bars drop all the way down to empty and the fuel light starts to flash which I understand is what is suppose to happen. Then when I ground the pink wire at sending unit the gauge then goes to full. Is this the correct way to test wiring and gauges and point more toward sending unit? Yes.

6. Is it possible that the sending unit is not giving correct resistance reading even though it is changing? Yes. Or can the resistance be correct but gauge is not reading it correctly? Highly unlikely.

7. one last one please. Is it correct that they changed in 94 so if I wanted to upgrade to any newer digital gauge for after 93 I would need to get additional wiring harnesses to convert to newer gauges? Tachometer only. Could I convert just one of them (fuel) and not have to upgrade tach to the new style? Yes. If i convert to analog then they will not be lighted correct? Yamaha analog gauges have internal lights.

thanks,
GLS

See following diagram.

Old style senders are known to be crap. Not worth a damn. Useless. Problematic. I bet it is your sender. If it is not a ground then it is the sender.

Do yourself a favor and install one of these:

CENTROID PRODUCTS - Computerized Tank Display - Electronic Senders - capacitive fuel gauges

[GLS062866]

guys thanks for the replies. couple of things.

1. I will recheck the ohms reading but I think that it was within those ranges.

2. I must have a wrong part number on the fuel gauge/speedometer because I do not see a plug to get to any dip switches. There is a rotary dial that can be set for the speedometer reading units but no other plug of opening.

you think this is a better sending unit? hate replace it if that is not the problem but gauge seems to be working properly correct?

thanks,
Greg

[boscoe99]

How about posting a photo of the back and the front of your speedometer?

[boscoe99]

guys thanks for the replies. couple of things.

1. I will recheck the ohms reading but I think that it was within those ranges.

2. I must have a wrong part number on the fuel gauge/speedometer because I do not see a plug to get to any dip switches. There is a rotary dial that can be set for the speedometer reading units but no other plug of opening.

you think this is a better sending unit? hate replace it if that is not the problem but gauge seems to be working properly correct?

thanks,
Greg

If the bars go low and flash when the sender is disconnected and if the bars go to the full up position when the sender wires are connected together then that indicates to me that the gauge is working correctly.

Have you ohm'd out the wires from the gauge to the sender? Excessive resistance in the wiring will cause the bars to read on the low side.

[GLS062866]

boscoe99 no I have not done that. I did just redo the bullet fitting from pink to white on gauge but I guess my tests have not been on the pink wire itself. The sender is changing ohms but it may not be getting through wire correctly. Is that what mean? What would the resistance be for that 4 ft of wire be? What gauge wire should the pink one be?

i can not figure out how to add pictures but I will continue to try.

[tmann45]

What would the resistance be for that 4 ft of wire be?

Zero or very close to it.

[zenoahphobic]

sending unit

GLS.... not withstanding any of the above, you can consider "recalibrating" your sender unit by adjusting/bending/lengthening your float arm so that full correlates to full on the guage.

If there is a negative it would be the sensitivity of the reading.

Just a thought saving money.

[GLS062866]

I dont think that will help because i have the sending unit out of the tank and with the arm all of the way up it will not go any higher. The resistance on the wire from sending unit to gauge was almost nothing and I even ran another wire from sending unit to gauge and grounded sending unit directly to battery and the bars will not go any higher. So I am assuming the sending unit is not acting correctly.

GLS

[erniefish]

Should read about 33ohms full, 240 empty,I just put a new tank in a boat, sender worked for less than a hour, got a new one, problem solved, I too thought it was the gauge, but my meter proved me wrong. Senders are cheap,replace it

[zenoahphobic]

I dont think that will help because i have the sending unit out of the tank and with the arm all of the way up it will not go any higher. The resistance on the wire from sending unit to gauge was almost nothing and I even ran another wire from sending unit to gauge and grounded sending unit directly to battery and the bars will not go any higher. So I am assuming the sending unit is not acting correctly.

GLS

Notwithstanding crappy sender, you would actually bend the float downwards.
To check if your float would be at its highest look to see opposite it's hinge, whether the brush has actually reached the maximum of its travel?

I am saving up for one of those capacitive senders.

[zenoahphobic]

Sorry I meant to add, you did the test Boscoe said rule out the gauge - I think it failed? So gauge culprit?

[steven knight]

Hey Greg,
I have the same problem. did you manage to fix it? if i short the white wire to the black on the back of the gauge i still only have 1/2 a tank.