Aftermarket gas gauge wiring

[WagDatto]

The gauge has a tab for power, ground and sender. I believe I have an S13 sending unit.

I've searched for the answer, but couldn't find it, and the FSM wasn't too much of a help either.

Basically, I hooked up the green wire and the gauge went straight to 3/4 full at half a tank, and stayed there at a full tank. Is it the float that's the problem, or am I missing something?

The two black wires are ground; one for sending and one for fuel pump. The green wire is sending and red is... low fuel light?

Any help would be appreciated, It'd be nice to have a fuel gauge in the Wagon!

[g6civcx]

This portion of the FSM is a little difficult so I'll help you out.

Black/yellow - fuel pump power
Black - ground
Green/blue - fuel level sender
Black - ground
Red/black - low fuel level switch
Black - ground

You have to be very careful that the gauge works on the same resistance range.

full - 4.3-5.8 ohms
empty - 78.3-84.8 ohms

Some gauges can be customized to read any range (like my Racepak), but most gauges will only work with a specific range.

Connect the signal wire on the gauge to the green/blue. If this doesn't work, check this wire for damage.

I highly suspect that you have the wrong gauge.


If you suspect your level sender is bad, measure resistance between the green/blue wire and one of the black wires. Look for the black wire that gives you continuity out of the 3.

[Mikey444]

Where did you get your aftermarket fuel gauge from? And are you making a custom cluster?

[WagDatto]

Mikey, the gauge is just a cheapo part from NAPA auto parts. Custom cluster, kind of... It's all in a Datsun 510 with a KA swap, so not much sticks with OEM anymore!

G6 - Thanks, I thought I knew what all the wires did, as the red/black didn't send anything to the gauge. I will have to check and see if the resistances are kosher or not. The other idea I had was that the float had jumped its track and needed to be fiddled with. In any case, I'll post back here if I have any other questions.

[WagDatto]

Okay, so the gauge I got definitely doesn't match up with the ohms from the stock 240sx sending unit. Unfortunately, neither does the stock 510 gauge. Anybody know of a cheap brand that will offer the correct reading on a stock 240sx? I'd prefer a 2" diameter, as it will fit in the gauge "cluster" that I have set up already.

[DohcKA]

i need me one of those for my 86.... gas gauge=failed... i drive until the light comes on haha

[WagDatto]

Haha, I don't have a light OR a gauge, so consider me fubard!

[lazierhobo]

yeah i would really like to find a solution to this as well...i too am in the no gauge no light boat.

very interested to find out what you guys discover!

[monks]

i think autometer makes a gas gauge

[WagDatto]

Actually, yeah, I had to word it just right in a google search, but I did find an Autometer gauge with adjustable ohms from 0-280.

THIS would be perfect. I wasn't finding any other gauges that were full at 4.3-5.8 ohms and empty at 78.3-84.8 ohms. I called Autozone, they carry it at a price of about $117, but to have a working gas gauge, I suppose it's worth it, right? Just gotta save up now. Thanks for all the input, guys, especially to G6CivicX for the ohm readings at empty and full. Helped narrow things down a lot.

[g6civcx]

Thanks for the praise.

My only recommendation would be a programmable gauge like that one. My Racepak has a built-in programmable gas gauge.

Otherwise, the closest application would be Ford pre89 or Chrysler. These cars have 10 full and 73 empty. Not quite exact but it's the closest you're going to get.