68 Fuel Gauge

[68ashgoldRS/SS]

Troubleshooting a '68 Fuel Gauge... the needle remains stationary at the 3:00 position regardless if battery is connected, switch on or off... suspect that the gauge itself is bad given this scenario.  Anyone agree/disagree?   I would guess that if another issue (sending unit) it would at least move, and be somewhere in the full to empty range?    Thanks in advance for your comments/suggestions.  Ed

[cook_dw]

Make sure the wire off the sending unit is grounded.  If you have a spare sending unit plug it into the rear harness & ground it and see if you can make the gauge work by moving the float.  If it doesnt then its the gauge.

[68ashgoldRS/SS]

Thanks Darrell.  I guess I assumed that since the gauge needle is residing way out of the E-F range that is was bad.  Will need to pull the tank I suppose to confirm that....

[cook_dw]

If you have another sending unit or an old one just unplug it from from the rear body harness in the trunk and use a jumper wire from the plug and ground the other side of the unit.  Should work if the gauge is working.  Sounds like you might have a ground problem though.

[68ashgoldRS/SS]

Thanks Darrell, finally got around to troubleshooting the fuel gauge...  I separated the connector under the trunk lock/latch mechanism, and grounded the tan wire going toward the gauge... sure enough, the needle went ot Empty....  So it appears that I need to pull the tank, recheck the ground, and most likely replace the sending unit...  I should have checked the sending unit prior to installing the tank... shoulda/coulda...

[cook_dw]

I bet the ground wire that is on the sending unit is broken.  They are just soldiered onto the lead.

[68ashgoldRS/SS]

Just curious.... if it was a broken ground on the sending unit, should I be able to test this by grounding the fuel line tube coming from the sending unit (which I can do without pulling the tank)?  Doesn't it have the same ground potential as the sending unit ground?  I'm trying to remember if the ground is a lug next to that tube on the sending unit.... That would quickly tell me if that connection is bad/broken...

[cook_dw]

You are just grounding the unit itself.  So yes that should work as long as the tube is still in good tight contact with the unit.  Obviously I wouldnt leave it that why but to test yes it should work.  In reality you should be able to ground the tank as a whole and it do the same thing.  (Im sure you know this but) I just wouldnt do it with gas vapors floating around.  Make sure you have a fan blowing the flumes away from you.

[68ashgoldRS/SS]

Yep... I was thinking that the tank was insulated from the sending unit by the seal, but I guess where it spins onto the tank via the bayonette connection it would be metal to metal...   If that's the case I'm thinking it is probably not a ground wire issue as the tank support straps should be grounded, therefore grounding the tank..  But will give er a whirl and see what happens!  Thanks again Darrel, your help has been great!

[cook_dw]

You should have insulators on the straps. & cushions on top of the tank to the floor so I would still check it to make sure..

[JohnZ]

You should have insulators on the straps. & cushions on top of the tank to the floor so I would still check it to make sure..

No Camaro was ever built with insulator strips between the tank retaining straps and the tank, although all the vendors want you to believe they were.

[cook_dw]

I just assumed that he put the rubber between the straps. 

[68ashgoldRS/SS]

Thanks Fellas,  no luck.... The ground wire is in the correct location according to the AIM, and has a solid ground connection at the terminal and suspect it's good on the sending unit end as I tugged on a bit. I tried alligator clip ground alternatives, and ther circuit is still wide open....   It's got to be the sending unit.  Good to know anyway!  Will get a sending unit on order, and drop the tank when it comes in...  I understand that the 4BBL cars get the larger fuel line tube (3/8") when ordering....    Any sending unit vendors you guys would stay away from, or recommend?  Here's one I found on ebay from Summit Auto that's priced reasonably.... http://www.ebay.com/itm/68-69-Camaro-68-69-70-71-72-Nova-Fuel-Sending-Unit-3-8-CAGT68-1-/221030543751?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A1968%7CModel%3ACamaro&hash=item3376727187&vxp=mtr#ht_1653wt_1362
Thanks again, Ed

[JohnZ]

I understand that the 4BBL cars get the larger fuel line tube (3/8") when ordering....   

ALL V-8's used the 3/8" main fuel line, and L-6's used the 5/16" main fuel line. V-8's with Q-Jets also used a vapor return line.

[bertfam]

V-8's with Q-Jets also used a vapor return line.

For 1969. 1967 and 1968 didn't use return lines.

Ed