70 RR Gauge ?'s

I just got the RR running and my gauges are pegging out on it while it is running. I checked all the gauges before I put the dash in. My gas gauge isn't working at all have new sending unit. The temp. and oil gauge peg out when I turn the key on. What could be causing this? It has a good reducer in it. It has been a long time getting to this point but the motor sure does sound good. Any info. will be a great help. THANKS RONNIE Also gas gauge does have a ground on it.

test the voltage limiter at the back of the gauge?

The limiter was checked before it was put back in. Why would 2 of them peg out and 1 not work at all? Thanks Ronnie

I must have misread your post.

It is possible one of the three gauges maybe bad. Did you check to see that the voltage is 5 volts? is there a good ground for the gauges?

I checked all the gauges while I had them out and they all checked good. The ground on my gas tank may not be good but I'll check it in the morning. The 2 gauges didn't start pegging out untill I started the motor. Would a new motor maybe run more than 80 lbs. of oil pressure? The gauge just goes to 80. If the temp. sending unit is bad would it short out? I'll just have to start checking everything. If you think of any thing let me know. Thanks Ronnie

Strange my last post on how to test a gauge is gone...

Basically if you put a 73 ohm resister at wire going to the tank (disconnect it) and put the open end to ground it should show empty.

wire-resistor-ground

8-12 ohms should go full.

~42 should get you 1/2

if wrong it could be your voltage to the gauge, wiring issue, or the gauge itself.

I unhooked the temp. and oil gauge and they both went down, I'm thinking maybe the senders are bad. I have had them a long time. They were just laying in the shop for years. I haven't messed with the gas gauge yet but I'll bet it isn't grounded good. The car is under coated and I'll bet the gas line isn't getting a good ground. Any other ideals???? Thanks Ronnie

You can still test for movement and voltage.

As mention in other post disconnect and ground the wire leading to the gas tank sending unit.

Turn key ‘on’ position

It should go toward full, turn key off and do not allow it to stay there for too long.

Now disconnect the wire completely. It should go toward empty if not already there when you turn the key on.

Put a voltmeter at the gas tank lead while not connected to the sending unit. I think you should see you should see 5 volts.