Fuel Gauge/Sender Question

[daniel123]

So I bought the fuel sender everyone here recommended last fall and had it installed at the local marina shop at the same time I had the new dash assembly put in, with a new fuel gauge, and topped off the tank for the off-season -- so I expected the gauge to read full, 'cause the tank was. But when I went to used the boat for the first time since, last week, while burning a quarter tank of gas, the gauge read empty when the key was off and jumped and stayed on full when on. No in between. Does this mean it's a bad/no ground?  Here is a photo; the wires shown are those leading from the wiring harness for the sender, which go off screen for a few inches, and wired to the dash panel. The one black wire is split to two, as you can see. Does this look right?

[Capt. Bob]

NO

First, cause it's too small to see.

Second, again too small to see but it appears to me that you grounded both the ground (duh) and the sensor feed.  
Still too hard to make out.

Is the white wire from the sender attached to the S post or pink or whatever color on the back of the gauge?

[seabob4]

What Bob said.  That is a WEMA sender, black and white off the sender.  Black to ground (corresponding black wire in the hull harness), white to pink.  And might I add buy some adhesive lined heat shrink butt connectors to give some longevity to those terminations?  

[daniel123]

Guys, I have posted the pix larger in my gallery at Daniel123 which should help you see how it's wired now. I'm not sure I understand what you are telling me that I need to do, wiring-wise, other than use better connectors. Help -- in detail!

[Capt. Bob]

Guys, I have posted the pix larger in my gallery at Daniel123 which should help you see how it's wired now. I'm not sure I understand what you are telling me that I need to do, wiring-wise, other than use better connectors. Help -- in detail!

Well.....

For some reason my definition of "larger" differs from yours. My computer could be suffering from "dburr syndrome" which may not be curable so......

OMC fuel gauge. Guessing yours looks similar?



Back side of same gauge.



OK, starting from the top left of the gauge in this pic.

1. Ground post for light,unmarked.
2. Ignition post. This is the switch power post allowing the gauge to receive 12v when you turn on the key. Marked "I"
3. Gauge ground, marked "G"
4. Sender post, marked "S"  (Note, I attached a yellow wire to this for ID).

That stated, it appears in your photo and by your description that you have attached both wires coming from the new WEMA sender to what appears as black wires.
Again, your statements as to what is occurring indicates to me that you have wired both sender (white) and ground (black) to the ground on your boat.

Could this be the case?

Does the wire spliced to the white wire on the new sender terminate at the "S" post on the back of the fuel gauge.

Your turn.

[Georgie]

Daniel,

the photos you posted in the gallery appear to already be reduced in size (unless I just didn't surf long enough to find the full size ones... :P ).  Next time, post your full size photos there. Only the forum needs reduced photos.

To add to both Bobs' guidance, the black shrink tubing leaving the top of the sender and going towards the bottom right of the photo should contain two wires (your pic doesn't show the terminal end of those wires so I can't tell where they go).  Those two wires should be white and black like SB mentioned.  Crimp (using the better heat-shrink adhesive lined terminals) the white one to the pink or red wire that runs directly to your fuel gauge, and the black one to any portion of your black ground circuit.  You should also take the time to run a green ground wire from the body of your tank to your fuel cap on the gunwale.  See Fletch's rebuild thread for some recent discussion on this.  Hope that helps.

Based on your comments in your earlier post, are both wires protruding from the WEMA shrink tubing black?  If so, you may need to swap/reverse your connection or break out the voltmeter to collect more info.

[daniel123]

It looks like he wired the pink wire from the WEMA to the correct red wire that goes direct to the gauge and the black wire from the WEMA he spliced into a black (ground?) wire he located under the deck. Keep in mind, I had the new sender installed the same time I had him put in a new (to me, but looked brand new and exactly like the AS Osprey dash he removed, except for the gauges/switches included and layout) AS dash panel with gauges pre-wired, etc. Since the gauge jumps to full when I turn the key, it's getting power. Just not showing levels.  

So I can upload my original 6MB images to the gallery? I'll try that now.

Dan

[RickK]

The gallery will size them down to 1024x768 automatically.  Then follow the instructions in each forum (top posts of forum) and scroll to the part right after uploading and follow how to get them into your topic - it's very simple.

[daniel123]

It worked! Thanks, Rick.

[daniel123]

My electrician buddy who rewired it this week said the the 'pro' installer didn't properly ground the sending unit, as you guys suspected. The gauge still reads Full when the key is on, but that may be because the 45 gallon tank probably still has about 35 gallons of gas in it. Should it be showing that level or do I need to burn more to get the sender/gauge to start reflecting the actual fuel level? Is there any way to test it on the trailer?

[slvrlng]

It should show some difference from full. How much is dependent on angle of boat on trailer and how close the bottom of the slide on the sender unit is to the bottom of the tank. On my hull I don't think I will ever run out of gas. When my gauge is showing 1/2 full its actually 2/3. I would rather have it this way as it gives me a nice reserve.

[daniel123]

Hm. Unless it was installed wrong, (it's a new gauge and sender) maybe it's still showing full because the boat is on the trailer on ground that is not exactly level?
If not, is there a way to test/adjust the float? Thanks for the idea and the input, Lewis.

[Capt. Bob]

If not, is there a way to test/adjust the float? Thanks for the idea and the input, Lewis.

You could take it out and slide the ring along the shaft and watch the gauge. I spent some time with mine and made up a little chart for position relation to fuel quantity because I had too much time on my hands. I still put 99.9% of fuel estimation into my Flow Scan.
There is no adjustment to the float ring that I saw.

Good luck.

[daniel123]

Thanks, Bob. I'll give that a try.

[Georgie]

maybe it's still showing full because the boat is on the trailer on ground that is not exactly level?

Almost 100% guaranteed to be the case.  Especially if your sender is towards the aft end of the tank and your trailer is inclined.  Level her out or burn some fuel and see if the gauge works as it should before you tear back into her.