Frankie the Fink

With a full tank it only reads about 1/2 and seems to settle in arbitrary positions after a drive. How hard is it to change a sending unit on this car ?

62Jeff

Pretty easy to change the sending unit.

Just open the convertible top deck lid, remove all the screws from the fiberglass cover in the convertible top well, and ta-da the fuel tank is right there.

May also want to add an extra ground from the sender to a frame mount, so that your fuel gauge doesn't deflect when you hit the brakes, or dance when the signal lamp is blinking.

Jeff

AZDoug

100% on the extra ground from the sending unit to the frame.

Get some strip caulk to re seal the gas tank cover.

replace the hose from the filler neck to the gas tank while you are in there. trust me on that.

Doug

JohnZ

Also check the long rubber vent hose from the passenger side of the tank to the gas filler cavity while you're in there.

Frankie the Fink

Are the screws holding the deck lid latch in the photo a good ground point ?

I'll definitely do the hoses and caulking as well.

Chuck Gongloff

No ground there, just screws through fiberglass.

Ground it to the frame. Chuck

AZDoug

I grounded mine using 10 gauge wire (overkill), and soldered ring terminals to the wire. Attached one to one of the screws that holds the sending unit to the tank, and ran the other end of the wire down out next to the fuel line through the existing hole for the fuel line and attached it to the frame using one of the fuel line retaines on the side of the frame rail.

The ground solved a number of problems.

Doug

wmf62

me too...
Bill

ps: the gauge reading is still not linear....

Frankie the Fink

Well that is what I will do then; with some smaller gauge wire naturally. Got so I always ask about such things on here before fixing something just because you get those little 'life saving' tips from time to time.

Frankie the Fink

Somebody had already run the sending unit ground wire and I ohmed it to the frame and its a nice job. The sending unit attaches to the fuel line with a rubber hose and two clamps; from what I read this is not original..there was a nut and flared fitting attachment...correct ?

Found one 'soft spot' in the fiberglass next to fuel tank...about the size of a quarter...can I just use regular Bondo to fill it in ?

wmf62

my 62 uses rubber hose & clamps to connect all the metal lines.

if i was going to make a small repair and not use glass mat & resin, i would use one of the filler products that have strands of fiberglass mixed in with it. 'bondo' type products are intended for filling dents, etc, not holes, and have very little strength for spanning open distances.

i don't know how you got a 'soft spot' unless something dissolved the resin. if it is truly 'soft' then it should be cut out and replaced with resin & mat.
Bill

david srour

One good easy way to improve ground and brake light/fuel gauge interaction is to run nice ground wire from taillight ground to rear body mount attachment bolt.

62RDSTR

Hi,

I'm pretty new to mechanics but replacing the sending unit has got to be one of the easiest things to do.

As others have mentioned, you might as well replace all rubber (filler neck, venting hose, etc...) since you are there. Do a survey prior to ordering parts. I pulled my sending unit out and noticed I had no filter attached to it.

If you are not sure if the sending unit is working properly, you can take a multimeter to the sending unit and take a couple of resistance measurements. Slowly move the float and you should see a change in resistance (between 0 and 30 ohms going by memory). This helps in determining if it is a gauge, wiring, grounding, or sending unit issue.

I had an excellent paper that assisted in troubleshooting issues like these; unfortunately, I recently lost my computer and had to rebuild. However, if you do a search for "troubleshooting gauges" you will find it.

Jim

62RDSTR

P.S. Make sure the sending unit is out of the tank and in a well ventilated area. Some suggest using a wood spoon to move the float.

Frankie the Fink

Sure nice living 50 minutes from Eckler's !

I replaced every clamp and piece of rubber under the deck lid including filler neck grommet & vent hose grommet. Good thing too the old stuff was nearly rotten and stiff with age. The bad news is that the new sending unit works and reads about 1/8 tank higher than the old one but its still way below full and I know the tank is topped off. So I guess the gauge is crapping out. Is there any recourse to fix it other than sending it off for 3-4 weeks ? Nobody makes a repopped version ?

Otherwise I'll leave the darn thing in and just drive using "Kentucky windage" for the fuel level.

Frankie the Fink

Oh, and Bill, I definitely think the soft spot is where some solvent or other fluid ate up the fiberglass. Especially since it is almost a perfectly round spot. I'll check out some mat and resin products but I haven't done much fiberglass work since my surfing days. Errr...at which time my vette was rolling off the assembly line - sad to say !

I did have one shock - on the passenger side looking way down at the front bottom of the gas tank I found a bunch of wadded up fiberglass insulation -- thought sure I finally found some half-@ss repair I'd have to work on. Nope ! A mouse was camping out in the vette at some point in time (leaving the usual presents)...everything in the area was sound and solid - thank goodness.

wmf62

... a 'quarter sized' spot will be a great way to reacquaint yourself with the 'itchy' art of fiberglass repair...
Bill

if the glass fibers are still inplace/intact, then you just might be able to work enough resin/hardner into the fibers to saturate them and after it cures smooth it off with some body filler.

wmf62

check the travel of the float arm on the new against the old; it may be possible to bend the float arm so at least you know when it's full. but i would be more concerned about it's accuracy at 'empty'.

when i fill my tank, it registers full, but it doesn't take many miles for it to start to drop. and i know from experience that when the gauge says 1/2 full it only takes 5 gallons to top it off (15 gallon tank...). thankfully when it gets towards empty, it is quite accurate.
Bill

Chuck Gongloff

You know you can adjust the sender float...like adjusting the ball assembly in your toilet tank.

You can bend the rod up/down to change the float position, possibly making the rod swing further/less, and thus changing the "ohms" reading being read by the gauge.

You might be able to get the gauge to read FULL by doing this.

Chuck

Frankie the Fink

I'll try that tomorrow - I've done enough on the vette today (or so I've been told by She Who Must Be Obeyed!)