[JimTaylor]

I'm at my wits end here -- I've a 65 Pontiac Lemans, and my fuel gauge always reads full now. I went through a diagnostic from a body shop manual specific to that year, make & model, and it said if a voltmeter is reading 3-5 volts coming through to the sending unit, then the sending unit must be bad. (I.e., I'm getting voltage so there's no break in the line, so it must be the sender.)
However, I bought a new sender and still have the problem. I didn't install it, but just hooked it up, grounded it, and moved the arm up & down -- the fuel gauge wouldn't budge.

I tested the sender, and I think it's fine.

Any other possibilities?

Thanks,

Jim

[JimTaylor]

I'm at my wits end here -- I've a 65 Pontiac Lemans, and my fuel gauge always reads full now. I went through a diagnostic from a body shop manual specific to that year, make & model, and it said if a voltmeter is reading 3-5 volts coming through to the sending unit, then the sending unit must be bad. (I.e., I'm getting voltage so there's no break in the line, so it must be the sender.)
However, I bought a new sender and still have the problem. I didn't install it, but just hooked it up, grounded it, and moved the arm up & down -- the fuel gauge wouldn't budge.

I tested the sender, and I think it's fine.

Any other possibilities?

Thanks,

Jim

[Zimtok]

Usually it is a bad ground. You may want to double check the ground. Don't forget the guage in the dash needs to be grounded also.
I would also check the rest of the wiring. In fact I would bypass the wiring in the car and run new temporary wiring.
I would also try another fuel guage, one that you know works. OR try the components, fuel guage , sending unit,and set up a mock wiring on the bench.

------------------
A.S.D.Zimtok

[Poncho64]

Mine does the same thing in my 64 except when it gets low on gas and the fuel sloshs around going around corners an stuff the needle bounces. Any suggestions?

[JonnyP]

My '64 LeMans fuel guage seems to be wigged out too - mostly seems to be in the correct general area, but bounces around alot and never goes to completely empty or full. Have a new sending unit, wiring harness, and good ground at the tank. I'll check the grounding at the guage, but if that's okay, then I guess it must be the guage. Anybody know where to get nos or repro gas gauges?

- Jon

------------------

[Ccass]

It is pretty rare for the little dash gauge to go bad. If your needle is "pinned" to the right side, you have a grounding problem as mentioned above. Check your dash ground, ground straps in engine compartment and wiring going back to the sending unit.

New sending units are available.

For prices click here; http://64.135.37.51/iwwida.pvx?;prod..._tree?comp=PY1
go to rear Quarter Panel/trunk; then Fuel sending units.



[This message has been edited by Ccass (edited 06-18-2001).]

[Peter Serio]

NOTE: 64 fuel gauges work off of a 30 ohm "scale" while 65 and up gauges all work off of 90 ohms. IF YOUR GAUGE IS "pegged" on F then you have a open circuit in the tan wire running from the dash gauge to the tank unit. NOT A GROUNDED WIRE, if you ground the tan wire anywhere from the dash to the tank then your gauge will "read" E. Also the 64 type of gauge needs a service about once every 25 years or so,..................
There are two drops of special grease that prevent the pointer from flopping around when you go around corners, etc.
You need to replenish this grease, over time it evaporates and the pointer swings around a lot more than it should. You cannot interchange a 64 gauge with a 65 unit, either the dash unit OR the tank sender, BOTH MUST of the same year for it to work properly, I do not know what ohms(30 or 90) the new senders are that they are selling now as new, but I'd bet it's the one for 65 and newer.

------------------
Peter Serio
Owner, Precision Pontiac

[Ccass]

Nice post Pete! Thanks.

30 ohm 1964 and 90 ohm 65-67 sending units are both available. Physically both these tank units look and mount the same. So theoretically you could add a 65 gauge cluster and a 65 tank unit and you should get proper reading. No?

[Old Man Taylor]

Peter - Please go into more explanation of the special grease and its application on a 64 GTO fuel gauge.

------------------
Jim

[JonnyP]

Yeah, I'd sure like to hear more about the 25-year service required for the '64 guage. Mine "twitches" when the key is turned, as well as when I go around corners, etc.

Also, can I measure the resistance of the sending unit across the lead to ground to tell if I've got the 'right' 30 ohm (versus 90 ohm) unit?

Appreciate the good advice - Jon

------------------

[Peter Serio]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Ccass:


30 ohm 1964 and 90 ohm 65-67 sending units are both available. Physically both these tank units look and mount the same. So theoretically you could add a 65 gauge cluster and a 65 tank unit and you should get proper reading. No?
Yes, Chris you are correct. As long as you use both parts that match your in business!
On the standard instrument clusters there is a slight difference between the appearence of the 64 fuel gauge(as seen in the dash) and the one they used in 65-7 in all the lemans and GTOs. The gauges will interchange in the cluster with no problems as well as the fuel sending units as you stated.
[/B]<HR></BLOCKQUOTE>



------------------
Peter Serio
Owner, Precision Pontiac

[Peter Serio]

Yeah, I'd sure like to hear more about the 25-year service required for the '64 guage. Mine "twitches" when the key is turned, as well as when I go around corners, etc.
Also, can I measure the resistance of the sending unit across the lead to ground to tell if I've got the 'right' 30 ohm (versus 90 ohm) unit?

Appreciate the good advice - Jon

Originally they used a special grease made from the body fat of whales, sperm whales I believe, since they have since been placed on the endangered list that grease is no longer available. The grease buffers the pointer's movements. I use a synthetic grease called CV-2, it's made by the red line oil corp. If you want your fuel gauge "serviced" tested and calibrated, you can EM me and then and send it to me, it only takes a day turn around, I do charge a small fee for my time.
You can test your sending unit, BUT DO NOT!!!
I repeat DO NOT, run 12 volts OR car's power through your sending unit. An ohmmeter that uses a 1.5 or 2-1.5 volt batteries is best to use. ONLY Test the sender with the key turned off and the sender's wires (BOTH)tan and ground disconnected from your car! if you run any more than 3 volts through your sender you will need to buy a new one from Performance Years!



------------------
Peter Serio
Owner, Precision Pontiac

['ol Pinion head]

Great info Pete!!!

Really glad to see you posting on the boards.