Fuel gauge

[B-Co Kid]

1987, 351w, c6 trans, no EEC

I initially had problems with the fuel gauge bouncing around and could not figure out why. So when I began restoring the B-Co I replaced the 33 gallon tank and used an aftermarket fuel sending unit bought from broncograveyard. Now, when the tank is near empty, the fuel gauge reads at a half tank. When the tank is full the gauge reads empty. Consequently broncograveyard has updated their website to say that some applications will read reversed. Nevertheless I now know that the sending unit is not the correct ohm rating and the empty/full should be reversed. My question is, can I use an aftermarket gauge that matches the sending unit in the tank? Aftermarket gauges require 12v for the lighting and a 12v from ignition, however, the original setup only supplied 5v to the sending unit. Do I only need a fuel level gauge, or will I have to get another sending unit and gauge kit??

 

[Skitter302]

You can swap a gauge to match the sending unit. The 12v to the gauge only power that gauge, your 5volt signal that comes from the sending unit goes to the input wire for the A/M gauge.

 

[Bully Bob]

The way I read these posts..., some words/parts are getting mixed up...??

Somebody correct ME if I'm wrong..!!

1) there's no voltage (5 or 12v) coming to or from the "sending unit" .... only ground, thru a resistor in the tank,

then one wire up to the gauge. 

2) 12v goes to a small volt. reg. under dash..., reduced to 5-6v..., then  5-6v to the gauge(s)

If it were me..., I'd put a stock "sending unit" in the tank..., test the gauge in the dash..., then feed

the gauge with the stock 5-6 volts.

Just say'n....,

B

 

[Seabronc]

Ditto Bully Bob !!  You are correct on how the gauge circuit works, Bob. 

While you are following Buly Bob's suggestion, check the wiring from tank to gauge for corrosion.  Vehicles this age tend to have a lot of corroded connections, and if in the tank circuit, that means poor indication.

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[B-Co Kid]

Unfortunately I haven't had any luck finding a stock fuel sending unit that matches my factory gauge. I have purchased two sending units that were advertised as having the correct ohm resistance, and both were the wrong sender. So instead of locating a hard to find sender and then dropping that Molly-whopper of a tank, or cutting into rear sheet metal for access, Im just going to wire that aftermarket sender to a matching gauge. Less time consuming, and less of a headache. I was just confused on the wiring. Anyhow, thanks for the response guys!!

 

[Bully Bob]

My guess is those senders are correct & as Seabronc suggested, there's something else amiss. 

Wires, connections, gauge itself..?

And, cutting an access (square or round) & fabricating a trap door is an excellent & often used solution to this issue.

 

[B-Co Kid]

Well I installed the aftermarket gauge, and the wiring was easier than I thought. Just ran one wire from the sender to the gauge, one wire from switched 12v source to gauge, and one wire from gauge to ground. The light for the after market gauge was the easiest. I didn't have to splice into any wires, just ran the positive wire to fuse location #17 and the other to ground. Wah lah, functioning gauge that dims with the headlight switch and has the same money green light as the cluster. I mounted it on the lower right faux wood bezel next to the opening for coins. I used a 2" circle saw to cut out the mounting location

 

[Seabronc]

Bronco gauges have always been a bit of a problem for accuracy. Nice picture of everything but the new gauge /emoticons/[email protected] 2x" width="20" height="20" /> .   Let us know how it works out for accuracy.

Good luck,

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