How to select fuel sending unit?

[Viper]

Before you condemn the gauge, check all connections including harness plug pins for a clean, tight connection. If you have a set of test leads, you can eliminate the boat's wiring for testing purposes, hook up the test leads and see if it reacts the same way. You should be able to do all you test hook ups behind the helm. If the needle still doesn't move when you ground the sender lead, replace the gauge.

[390Express]

Qr Bbpost Before you condemn the gauge, check all connections including harness plug pins for a clean, tight connection. If you have a set of test leads, you can eliminate the boat's wiring for testing purposes, hook up the test leads and see if it reacts the same way. You should be able to do all you test hook ups behind the helm. If the needle still doesn't move when you ground the sender lead, replace the gauge.

So if I ground the red wire at the sender, the gauge should read full?

[390Express]

Qr Bbpost Before you condemn the gauge, check all connections including harness plug pins for a clean, tight connection. If you have a set of test leads, you can eliminate the boat's wiring for testing purposes, hook up the test leads and see if it reacts the same way. You should be able to do all you test hook ups behind the helm. If the needle still doesn't move when you ground the sender lead, replace the gauge.

Grounded the red, gauge reads full. Bad sending unit for sure, looked like hell when I pulled it out of the tank. Is there a way to check if it's a 10-180 ohm, vs the 33-240? I have VDO gauges, so I'm guessing it's the 10-180, but VDO also makes a 33-240 sending unit.

[Midnightsun]

VDO is the odd ball in terms of ohms. If you have a model number of the sender or gauge, I would shoot them an email to confirm what you need.

[bud37]

Qr Bbpost Is there a way to check if it's a 10-180 ohm, vs the 33-240?

Sometimes the ohm range is stamped on the unit, clean the top and have a close look.

[390Express]

Qr Bbpost

Qr Bbpost Is there a way to check if it's a 10-180 ohm, vs the 33-240?

Sometimes the ohm range is stamped on the unit, clean the top and have a close look.

I bought the damn 10-180, but they weren't right (good thing they were only $17). Has about a 1/4 tank and the gauge reads full. The only number at the top of the gauge is 04045-47, but I can't get it to cross reference anywhere. Any ideas?

Seems like it should be a 240 - 33. The new sending units were likely putting out 15-20 ohms, and reading full. I suppose I can try lifting the gauge and seeing if it goes down.

[hausherrs]

I just installed this one yesterday in my aux tank. It works great. I just matched sensor height up to the old one and trimmed the main beam. Took 20 min.

Moeller 035729-10, Fuel Tank... https://www.amazon.com/dp/B000MTCRA0?re ... b_ap_share

[jrafaello]

Hey all I’m having an issue with my gas gauge on my 87 Santa Cruz. When I turn on the key it goes backwards. If I swap the send and ground wires the gauge goes to full. Is that the sending unit?
Can I swap it without taking out the tank?

Any help is as always appreciated!

[ColRon]

Qr Bbpost Hey all I’m having an issue with my gas gauge on my 87 Santa Cruz. When I turn on the key it goes backwards. If I swap the send and ground wires the gauge goes to full. Is that the sending unit?
Can I swap it without taking out the tank?

Any help is as always appreciated!

Are you swapping the sending and ground wires at the gauge? I’m assuming that’s what you did. You need to disconnect the sending wire from the sender itself. With it disconnected at the sender you shouldn’t see any movement either direction, since the circuit will be open. If you do have movement sounds like you have a short somewhere. Not sure about how the tanks in the Santa Cruz are set up, but generally you do not have to remove the tanks to replace the sending unit.

[jrafaello]

Ron,

I did all the tests I could find and it was the sending unit. I contacted Carver and they gave me the exact unit mfg and part number. I replaced it with one the parts store swore was a direct replacement for the original (Kysor Medallion). Of course it wasnt. It was a Universal one. No big deal except:

1. It doesn't work correctly with the dual gauge system (helm and flybridge). I unplugged 1 gauge and the other works fine. 9Clearly a resistance problem). No big deal, I only drive from the bridge.

Yesterday however,

I started the boat and the Tachometer on the bridge died.. I touched the back of it ( I was under there cleaning up wiring yesterday) and it started working again BUT the fuel gauge went from 3/4 of a tank to full! Gotta be a short or a bad connection right? But what? Grounding issue? Just thought I'd check before taking wires off the tach and not having the boat start.

Rafe