NiohShadow88

Hello, firstly nice to see this forums active. Ive got a 68 cutlass convertible, been working on the fuel gauge and determined it does work via a virtual bench test with a new sending unit, except for the 0 ohms empty position is 1/2 tank and the 90 ohms full positon is beyond full on the gauge. not so full as an infinite ohm situation but more so the accurate sweep distance from empty to full except its from 1/2 tank to beyond full tank (hope that makes sense). is there a way to re-calibrate the needle, IE move its starting position to Empty instead of 1/2. I can live with it im sure but still, curious if anyone has experience on this subject. thanks!

JohnnyBs68S

I've heard that the sending units are available in different resistance ranges, are you sure you replaced yours with the correct range?

The gauge in my '68 has never been "accurate", it would stay on FULL until about 1/2 the tank was gone, then it would begin dropping to EMPTY. BUT, the needle would point at F and E pretty accurately. More recently, it becomes intermittent when the outside temperature drops (it would open up and read way pass FULL until it got down to ~1/2 tank of actual fuel or less). Either my sender is going bad or I have a loose connection that opens up when cold.

NiohShadow88

I think older cars had a 0-30 ohm range i could be wrong but regardless 0 ohm should take the needle down as far as it can go. can even jump the sender signal stud to the ground stud or ground and mine pegs down on 1/2. im not sure if the needle just pops on and off, its almost like i need to pop the needle off and just reposition it lol. but normal situation way past full is an open or higher than nornal resistance situation. id guess your sender is bad rather than a weird wire opening up deal. i havent actually installed a new sender yet i just disconnected the guage and used jumper clips with a hot the new sender in my lap jumped the signal wire and jumped grounds for the guage and the sender. its full range of sweep seems like an accurate distance just a wrong starting point of half tank.

RWK

Make sure it's well grounded, just put my D88 tank back in and new sending unit, put 5 gal. in tank and seems about right, have yet to check with a full tank.

joe_padavano

The 1964-earlier cars used a 0-30 ohm sender. 1965-later use 0-90 ohm. They do not interchange.

Tri-Carb

On these older cars, from the factory, full scale on the float (tank full) is beyond (to the right of) F and the initial (tank empty) is below (to the left of) E on the instrument readout on the dash.

NiohShadow88

Has anyone by chace had the glass off and knows how the needle is attached? as ive isolated my guage completely from the car i know my problems arent any sending unit or ground related. its more like the needle has slipped. i know on newer guages the needle just pops off and can be moved around. my full sweep is roughly 12 o-clock to 5 o-clock ish with 0 ohms - infinite resistance where emtpy to full is roughly 12 o-clock to 3 o-clock with 0-90 ohms

JohnnyBs68S

I wish I knew how to R&R the needle, but I tend to agree that sounds like the cause of your problem (needle ~45 deg clockwise from where it should be). Not sure how it got that way (may want to check the electro-magnets attached to the needle shaft to be sure they are not damaged or binding on anything.........if that is even possible). My speedo has a similar need to make it accurate: It reads consistently 4 MPH slower than my GPS over a range of ~30-70 MPH. If you are able to get the needle removed, I would energize the gauge with the sender resistance wire shorted to ground to simulate an "E" condition and then mount the needle pointing at "E". Good luck.

NiohShadow88

alright so for the fuel guage at least heres what it looks like. little pin male on the guage and a lil female hole on the needle.