Del70

The sending unit is stuck in the full position after fill, and the drive to and from the Lansing Olds show. - I Ran through the quick checks to confirm the gauge is good, the sending unit has a good connection (ground) so I assume the sending unit is just mechanically stuck because of varnish. I added some fuel system cleaner, and tried to tap the tank bottom, hoping to free it up. I ran a hose in there carefully to see if it just might tap it and free it. Has anyone ran into this, and had any luck freeing up a stuck sending unit w/o removing the tank. tanks

oldcutlass

Have you grounded the wire at the sending unit to see if it will drive the gauge to "E"?

jaunty75

What were these "quick checks?" There is only one check to confirm the gauge is good. You've checked the ground, so that rule out one potential problem.

As oldcutlass says, verify that the problem really is the sending unit by disconnecting the hot wire connecting the gauge to the sending unit and grounding the side coming from the gauge. With the ignition ON, the gauge should go to E. If it does, then the wiring is fine, and you are correct to suspect the sending unit. But if it doesn't, you have an open in the line between the sending unit and the gauge. A gas gauge stuck on F or well past it is a classic symptom of an open circuit in the gauge wiring.

Del70

I disconnected the wire in the trunk, grounded that wire running to gauge, gauge went to E, I Also checked continuity of the wire from the tank that is grounded to the body. Just wanted to be sure that wire was not broke , and the connection to the body was good...The gauge is not past E, it is just stuck in the full position, after filling tank...

oldcutlass

Then I would agree with your prognosis, stuck sender.

Del70

I took another look at the gauge position..It is reading past full, ..as if it is being pegged. It is a rally pack gauge. I have filled the car before, I really don’t remember if the gauge would read past full. I don’t fill it often or drive the car much so I am not sure where the gauge would end up when the tank is full. I know when the standard fuel gauge has an open circuit, it goes to the 3 o'clock positio,...(I had one do this when the gauge cluster was not grounded).
I will read through these posts, get more info, understanding... thanks
https://classicoldsmobile.com/forums...hats-next.html

oldcutlass

If you unplug the wire with the key on it will peg.

jaunty75

That's the classic indication of an open circuit, whether it goes all the way around to the 3 o'clock position or not.

You said that you grounded the gauge-side wire, and the gauge went to E. This, plus the info you just provided above, suggests that the dash gauge is fine, and you are probably right that the sending unit is the problem.

If you're going to go through the trouble to drop the tank to fix the problem, and it sounds like you're going to end up having to do this since all your rapping on the tank and sticking things down the filler neck didn't cure the problem, you might as well put in a new sending unit instead of trying to fix the old one. They're not that expensive ($50 or $60), and then you won't have to worry about it again for 40 years. Have the tank cleaned and sealed at the same time. You mentioned varnish in your first post. All the more reason to drop the tank, have it cleaned, put in a new sender, and fix the problem once and for all.

Del70

.. I will add another bottle of cleaner and run it through and see if somthing changes, while I decide/figure out when to drop the tank. Need to also find the parts. Finding/getting a quality replacement sending unit and good quality, corret tank bothers me more than doing the all the work, having to do the work. I want to do this once. I still have the factory tank, I am sure it has some rust under the straps, so replacing it now vs latter make sense...thanks

oldcutlass

Any auto parts store can get one for you. Rockauto is a good source also if you like shopping from your couch.

jaunty75

I wouldn't be so quick to assume your tank is no good until you've actually dropped it and looked. I saw your other thread where you're asking about where to get a replacement tank, and I'm wondering why you're so quick to give up the ship on the one you have.

I needed to drop the tank on my '67 Delta back in 2010 when I needed to replace the sending unit, and I was prepared for anything as far as the condition of the tank given that the car was then 43 years old and had 129,000 miles on it. I also wondered what was under the straps. Well, I couldn't have been more pleasantly surprised. The tank was essentially pristine. No rust to speak of on the outside, and except for some loose crud that I vacuumed out, very clean on the interior. I was very pleased.

Even if your tank is rusty, have it checked. It might still be solid enough to be reused. You can have it cleaned and refurbished by the same people who do radiators.

If you do get the tank down and discover that it has to go, then, as oldcutlass says, get one from rockauto or something like that. These are readily available, and you don't have to try make one for a Chevelle fit.

Ditto for the sending unit. These are also readily available, Spectra-Premium is a good brand, and I would just get one and not worry about it.

From the tone of your posts, you seem to be expecting disasters at every turn and expect to be unable to find any parts. This is raising your blood pressure for nothing.

Relax. Take it one step at a time. Don't order a tank until you see what the condition is of yours. Don't assume this is going to be a one-day operation. Your car will probably be off the road for several days if you don't need a tank and perhaps a week or more if you do. Go ahead and order the sending unit right away, as that's worth replacing once the tank is down no matter what the condition of the tank itself is.

You could go over to Autozone right now and order the sending unit. They'll have it shipped to the store, and it'll be in tomorrow or the next day. They have both the with and without return line versions, so you're covered. If you don't know which kind you have, you take a look up under there or just wait until you drop the tank.

http://www.autozone.com/autozone/par.../N-iqqa4Z8vdfx


Autozone also has your fuel tank.

http://www.autozone.com/autozone/par.../N-iqqa4Z8vday


I'm not saying you have to deal with Autozone as any of the auto parts stores will be able to get these parts. They'll likely all have Spectra-Premium as well, so you'll get the same tank and sending unit no matter where you buy it from. Rockauto also sells Spectra-Premium, among other brands.

I have a Spectra Premium sending unit in my '67 Delta. I purchased it from rockauto, and it has been working fine for four years now.

hookem horns

Hardest part may the the strap bolts if rusted and be prepared to cut/replace. As others said, good quality repops of anything you end up needing for a 70 Cutlass fuel system are readily available. Big car owners are not so lucky.

Del70

I have the sending unit on order, will look at the tank and make a decision. I removed some fuel (about 10 gallons) and the gauge is now at 1/2 tank. gauge was either stuck or is not ready correctly, is off and no that tank was not full. ...I want to get the tank as empty as I can and see what the gauge does..