Replace Fuel Sending Unit?

[Toxarch]

I have 92 Skeeter 175 SF with a fuel gauge problem. The gauge always shows empty. I followed instructions to test the gauge that I found here. The gauge appeared to test fine. Checked the sending unit and it moved the gauge needle when I grounded the sending wire. So I guess my sending unit is bad. Though the voltage in the signal wire was only like 7 volts with a full tank of gas. Hope my conclusion is correct.

Will any generic sending unit work or do I need a specific one? I took some pictures of the tank information and pics of the sending unit... that might be rather hard to get to. You'll see in the following pictures.

Fuel Tank information. Seems like a large tank for a bass boat to me. I guess that is good since my gas gauge isn't working.

Here's the access to the fuel gauge sending unit. Might be hard to change it. Though, looks like someone might have changed it before.

And here's a pic of the top of the sending unit:

Any suggestions are welcome as far as what I need to get. Think I can get the old one out and the new one in without too much trouble? I might have to wait until winter to make sure I have plenty of time in case something goes wrong.

 

[Silvertip]

Re: Replace Fuel Sending Unit?

Disconnect the pink wire at the sender. Now measure the resistance (ohms) between that terminal and the shell of the sender. Sender resistance varies from 33 - 240 ohms depending on how much fuel you have. 1/2 tank should provide a reading of about 109 ohms. Empty is 240 and full is 33 give or take a little. If you have an idea how much gas is currently in the tank you can determine if the sender is working. Senders are generic so all you need to know is the depth of the tank when you order a replacement.

 

[Toxarch]

Re: Replace Fuel Sending Unit?

Disconnected the wire and put the tester to it. The gas tank should be near full. The voltage across the wires is 9.45 volts. The resistance across the sending unit is 300 ohms. When the wire is disconnected, the fuel gauge needle is bottomed out (well below E). When the wire is reconnected, the fuel gauge needle is just below empty.

So if the resistance is 300 ohms, then that should mean the sending unit arm is all the way down even if the tank is full. And therefore, the problem is indeed the sending unit, right? The tank is 13" deep where the sending unit is and the top of the sending unit is about 2-5/8" across.

Is this the right one?
http://www.iboats.com/6_12_Electric...3056050--**********.232368103--view_id.392305

I had some 100 ohm resistors... somewhere. If I find them I will try to use them to test the gauge.

 

[Silvertip]

Re: Replace Fuel Sending Unit?

The float arm may have broken off or is stuck down, the float may have fallen off or simply disintegrated or become fuel soaked. Pull it and check it.

 

[Toxarch]

Re: Replace Fuel Sending Unit?

The boat is used and I took it out only once since I bought it (and once before). The dealer I bought it from said it was full of fuel and I even topped it off before I went to the lake the other day.

So I picked up a new sending unit so that if the old one was bad when I pulled it out, I could just replace it and be done. I pulled the old one out and the little metal tab that hold the float in place had slid up the float rod. So the tank could get fuel in it but the float would just move up the rod rather than lifting the rod. I put the ohm meter on the rod and it seemed to test out fine. I fixed the metal tab, reinstalled the sending unit, turned on the electronics... and nothing. The fuel gauge still showed empty. WTF? Maybe I put it back in wrong. So I pulled it back out and then realized only the tip of the float had gas on it, the rest was dry. I tried to look down the hole and even put a probe in there. There was almost no gasoline in the tank.

I started trying to figure out if maybe I had a dual tank. There's nothing that indicated that I did, especially with only one fuel nozzle. I was baffled. I filled the tank the other day and the fuel even overflowed a little at the gas station. So I reinstalled everything and headed for the gas station with the boat. It's a 49 gallon tank and I really hoped there wasn't a leak in it. Put in some gas and the fuel can bubbling up like the tank was full. But I know it's empty. It's like there's a kink or a clog between the nozzle and the tank. Only way to add fuel was to very slowly pump it in. Couldn't even put it on the first notch to let it fill itself. Hit the switch for the gauges and the fuel gauge is working. I only put in 20 gallons for now.

I guess that problem is solved. And if the sending unit ever goes out, I know what to buy and how to replace it. Good thing I didn't drive too far on the lake the other day or I would have been stuck without any gas and not known it.

Thanks for the help Silvertip, I really appreciate it.