fuel, temp and oil pressure gauges all having issues.

[GoMangoBoys]

So the Fuel gauge, Temperature gauge and Oil Pressure gauge are not working correctly. 
1. Fuel gauge.  I think an adjustment is needed on the lever arm of the sending unit.  Is this common to need to do?  I know the sending unit works, as I tested it and used it to test the other gauges when I assembled the dash.  I added about 6 gallons of gas to the tank, but it still reads empty.  I think a 20 gal tank should read 1/4 with 6 gal in it.  Shorting the wire to ground makes it read full and an open circuit makes it read empty.  Can I get the sending unit out of the tank and adjust it without removing the tank?

2.  Temperature gauge.  I think my sending unit is bad.  The gauge reads C even when the engine is hot.  If I ground the lead, the gauge reads H.  I measured the sending unit to ground and it reads 249ohms.  I think this should be like 33 right?  I also checked that the unit itself is grounded and it is.  The case of the sending unit reads 0 ohms to ground.

3. Oil Pressure gauge.  This one reads H any time the key is on.  Open circuit or grounded lead does not change the reading.  If memory serves me correctly, the sending unit reads 33 ohms when the engine is off and 24 when it is running.  With the lead disconnected from the sending unit, I read 5.5 ohms to ground on the lead.

[Brads70]

Voltage limiter bad? You do have the ground strap on the fuel sending unit?
https://www.rosevillemoparts.com/product/sending-unit-ground-strap-7-5-inch/
https://www.rosevillemoparts.com/product/voltage-limiter_-e-body-71-74-b-body-oe-2209216/

[Jay Bee]

2. Temperature sending unit info. The last 2 pictures are my good one.

https://forum.e-bodies.org/electrical-and-audio/11/temp-sender/22656/msg272552#msg272552

[Jay Bee]

Can I get the sending unit out of the tank and adjust it without removing the tank?

Yes and make sure you're confident there's less than 1/2 tank of gas. Another thing to consider is sometimes the floats get holes and gas gets in them. Bending the arm is needed sometimes but I've never heard it being required that drastically (1/4 tank).

[GoMangoBoys]

Fuel tank and fuel sending unit are brand new.  Should have mentioned that.

[GoMangoBoys]

@Brads70  Voltage limiter is good.  Brand new, verified before the dash went in the car.  As for the grounding strap, I am guessing that is it.  Can't believe that I did not consider that.  I will try putting an alligator clip jumper on it and seeing if that is it.  That is embarrassing to have overlooked. Ugh!

[GoMangoBoys]

Adding the ground lead to the sending unit did not fix the problem. It appears to be getting a ground thru the tank.  I will add a permanent ground strap anyway.  The sending unit is measuring 60 ohms at the moment, but the gauge does not move.

[GoMangoBoys]

The fuel gauge is working correctly (mostly).  I took out the sending unit and verified that moving the float up and down caused a corresponding movement of the gauge.  Now when the float is fully down, the gauge reads at its limit below E.  When it is all the way up, it reads exactly F.  I think the offset might be caused by some resistance in the connection between the gauge and the sender.  I will be checking that soon.  In the meantime, I added some more gas to the tank and it now reads less than half.  I probably have a total of 10-12 gallons in the tank.  If it reads F when full and reads E when there is still 5 gallons in then that will be OK I think.  We will have to see what it says when I fill up the first time.

[chargerdon]

regarding the gas gauge...yeah...those floats are not all that accurate.   just remember the tank is only about 10 inches deep but about 24x24 in surface area.   The result is that it takes a minimum of 4 gallons to get the float to move at all..   So, in my 74 chally it takes about 5 gals for it to move the gauge off empty.    Float adjustment is usually only necessary if when completely full it doesn't read past the full mark.   On my 66 Charger it takes a really good fill for it to read full, and then empty is at about 3 gals left.   

Regarding adjusting the float, yes, you can remove the float while tank is in the car....however, first try to make sure the tank is no more than 1/4 full, and second, be careful not to make sparks or you wont care anymore...lol...   I use a wooden block to turn the hold down clamp...they say a brass punch is good also.   Regarding ground...there is a small (about 4 inch long clip that goes around the hose connection to provide ground to the sending unit from the gas line.   Adding a ground strap to the clip from the frame is a good option.