[72LemansFreak]

Hi all,

As the driving season fast approaches, I'm trying to work some bugs out in my LeMans. Some have been around for a long time and others are new. Neverending, as we all know.

I replaced the fuel tank and sender in 2007. Ever since then, I've had two minor problems:

1. When I fill the tank, the gauge doesn't go past full as it should. It gets about 1/16" from the full mark. After about 100-120 miles, I'm down to 1/4 tank, but it only takes about 10 gallons.

I have a sneaking suspicion that the replacement tank is smaller than the original. It might be 18 gal vs 20. Could the sending unit need some tweaking? Not sure if it would, as I thought all the GM units from that time were 0-90 ohm. Is there some way to adjust the sender to get it to read properly? Bend the arm on the float? Any idea what direction I would need to bend it? Thoughts?

2. The filler neck sits pretty low and makes removal of the cap difficult. I've bent the filler neck upwards and that seemed to help, but not enough. I don't want to damage it.

I've got some ideas brewing in my head as to what might be going on, but I would love some suggestions. I'd rather not drop the tank if I don't need to!


Thanks in advance!

[Txbobcat]

Why did you replace the sender to start with and did you get a good factory type unit? 2 gallons isnt going to matter that much. And you are getting 10 to 12 MPG?

[72LemansFreak]

I don't remember where I got the sender, possibly Ames or OPGI. The sender looked very well made. I don't remember the brand. It looked almost exactly like what came out. The original looked in terrible shape and worked only sporadically, even after checking and cleaning the ground. It was, however, more accurate when it worked.

You're right, 2 gallons isn't that much and I'm not worried about that, I just want the gauge to register full when it's full.

Yes, I'm getting 10-12 MPG. It's pretty much impossible to keep my foot out of it. If I wanted a car to keep my foot out of, I'd buy a Toyota Pious.

[Mister Pontiac]

Henry, I saw your post on the AZ Pontiac group earlier too, but didn't get a chance to respond there, but I'll answer here now.

To answer your question, no, I don't think the replacement tank is smaller, but I won't be 100% dogmatic about it. But if the fit and finish of the replacement tank is very close to your original (did you compare them side by side before install?), then I suspect the tank is the same.

I understand how your filler neck is improperly positioned too. I have a similar problem with the new tank I put in my '67 GTO. I ended up bending the neck a bit, and resoldering around the neck/tank joint. While it's better now, it too still isn't perfect. I've just learned that it isn't that big of a deal, and I'm living with it for now...

I would say the solution to your indication problem is to bend the float arm down. This will allow the rheostat more room to travel before the float tops out. Since it's currently reading 'low' for any given fuel level, that tells me the arm is sitting too high, and needs to be lowered. Basically, the arm is hitting 'full up' before the rheostat has a chance to make full travel, so by bending the arm down slightly, you will effectively readjust the measurement so the rheostat can make full travel. That should also give you a more accurate reading for any given fuel level.

Good luck, and I hope that helps!

[72LemansFreak]

Originally Posted by Mister Pontiac

Henry, I saw your post on the AZ Pontiac group earlier too, but didn't get a chance to respond there, but I'll answer here now.

To answer your question, no, I don't think the replacement tank is smaller, but I won't be 100% dogmatic about it. But if the fit and finish of the replacement tank is very close to your original (did you compare them side by side before install?), then I suspect the tank is the same.

I understand how your filler neck is improperly positioned too. I have a similar problem with the new tank I put in my '67 GTO. I ended up bending the neck a bit, and resoldering around the neck/tank joint. While it's better now, it too still isn't perfect. I've just learned that it isn't that big of a deal, and I'm living with it for now...

I would say the solution to your indication problem is to bend the float arm down. This will allow the rheostat more room to travel before the float tops out. Since it's currently reading 'low' for any given fuel level, that tells me the arm is sitting too high, and needs to be lowered. Basically, the arm is hitting 'full up' before the rheostat has a chance to make full travel, so by bending the arm down slightly, you will effectively readjust the measurement so the rheostat can make full travel. That should also give you a more accurate reading for any given fuel level.

Good luck, and I hope that helps!

Thanks, Todd. That makes sense! The tanks looked the same to me, except the new one wasn't rusty inside and out.