Olds64

Gentlemen, I'm going to return to the States soon. I'll be home on the 28th of Jan.

My first project when I return home will be to restore the fuel tank on my 71 98. I've already ordered a fuel tank restoration kit from Summit.

I'm certain my fuel tank needs to be restored. The hoses between the sending unit and steel lines are horribly deteriorated. The car smells like fuel whenever I stop and it's hard to start in the mornings. Plus, my fuel gauge doesn't work correctly. It's always bouncing around and doesn't read properly.

I believe the fuel sending unit for a 1971 Delta 88 will work on my 98. Am I correct? The only difference in full-sized fuel tanks between 71-76 should be that the Custom Cruiser had a different tank. Here is a link to the fuel sending unit from Rock Auto:

http://www.rockauto.com/catalog/more...450&cc=1213647

BTW, should I order new fuel tank straps from Fusicks? I was planning on reusing the old ones. I don't care if the old straps are corroded and ugly. They will get a coat of Rustoleum along with the exterior of the tank before reassembly. Please provide me with any tips you might have.

jaunty75

Yes, the fuel tanks for the full-size cars are the same, and that sending unit should work. It's the same one I put in my '67 Delta 88, and that car is supposed to take a canister-style sending unit which isn't made any more. But this fits and has worked fine for me.

As far as the straps, if the ones you have a structurally ok, I see no reason not to reuse them. Clean them up, maybe give them a coat of something bland like gray (I painted mine gold for the heck of it), and put them back in. It's not like they're something that stands out on the car when you look at it. They just need to be functional.

oldcutlass

I don't think a new sending unit is going to stop your floating problem though. I've been through that issue over the years and my opinion is if it registers full when you fill it, and slowly goes down then it's working. If its floating around I know there is still fuel in the tank and generally fill it between 1/4 and 1/2.

jaunty75

I wondered about this comment myself. Typically a bad sending unit results in the gauge just being stuck somewhere, usually on F or well past it, indicating an open circuit.

The fact that the gauge moves around, presumably when the car is moving, suggests that the float is working to some degree. But if it never settles down and gives a measure of the level of fuel in the tank, dropping the tank to investigate is going to be required, anyway, and if you're going to go to that much trouble, you might as well stick in a new sending unit.

Olds64

Thanks for the advice gentlemen. I MIGHT AS WELL replace the sending unit since I'm dropping the tank. I will also ensure my grounds are clean and secure.

I will post pictures when I drop the tank. I wouldn't be surprised if my tank is pretty rotten.

The Tin Man

I used tank sealer from Eastwood........AHHHHHH ETHAL ate it over the winter last year.They make a tank for a buick that fits perfect and it came with sending unit....... It was for my 71 88

Olds64

Well, I finally found the time to replace the fuel sending unit in my 71 98. Unfortunately, now the gas gauge reads E all of the time.

I ensured the ground was good. I guess I'll eventually do a check near the trunk latch as Jaunty75 outlined in the following post:

https://classicoldsmobile.com/forums...ge-issues.html

Unfortunately, I didn't take any pictures; however, the tank was surprisingly clean. Sometime in the past the tank was dented pretty bad. It didn't leak too much though. I ended up coating the inside of the tank with the Summit Fuel Restoration kit. I painted the outside of the tank with Rustoelum. I'll keep everyone posted.

jaunty75

You have a short circuit in the line between the gauge and the sending unit or at the sending unit itself. This likely has nothing to do with the quality of the ground as a bad ground, if the only problem, would cause the gauge to read F all the time.

oldcutlass

You need to check your wiring again, you may put your gauge wire to the ground stud. If you disconnect the gauge wire it should go past F with the key on.

Olds64

Thanks for the advice. Now all I have to do is find the time to do some troubleshooting.

2blu442

I missed your post from January. Welcome home! Are you done overseas or will you be going back?


John

66ninetyeightls

Do you have any places like this in your area?
http://gastankexchange.com/

The one near me completed restored my 98's leaking fuel tank and rebuilt the sender for under $300.

Olds64

John, thanks for the kind words. It's good to be back home with friends and family. To answer your question; no, I won't be going overseas again. I don't have to travel with my current job. I'm able to be at home where I belong.

Craig, I don't know of any places that specialize in fuel tanks. I know there's a shop in town that has a hot tank though. I thought about taking my tank to them but decided against it. I think they specialize in radiators though.

FWIW, I did do some troubleshooting. I put some spade connectors in the line next to the fuel filler. I pulled it apart and found out my short is near the tank. The gauge went up to F when I opened the line. I guess I either shorted a wire installing the tank, have a bad sending unit, or hooked something up wrong. I might tinker with it tomorrow. I'll let everyone know how it turns out.

oldcutlass

Well that rules out the gauge and all the wiring forward. I'd be curious to know what the outcome is.

Olds64

Ok, I dropped the tank again. I didn't find any pinched wires that were shorted to ground, so I swapped the 2 lines at the fuel sending unit.

Now the fuel gauge reads E all the time!

I made sure the tank was full. I put $70 of super unleaded in the tank until it was spilling out the top! (not that I wanted to put that much in it)

So, I'm at a loss. I drove the car about 45 miles to burn off some of the fuel. I'll have to drive it quite a bit more before I drop the tank again. My car has a 25 gallon tank. I figure if I drive it about 200 miles I might be able to siphon the last of it into a jerry can and drop the tank again. The question is do I want to mess with it again?

This whole fiasco started because my car starts poorly and has an off idle stumble. I did some reading and found that others have been able to cure similar problems by replacing the fuel hoses at the tank. I knew my hoses were rotten, so I decided to drop the tank, restore it, replace the fuel sending unit and re install everything. After all the work I've done the car still has the off idle stumble, has hard starting and now the fuel gauge doesn't work at all. At least before the gauge would bounce around and read full when I topped it off.

Anyways... I'm not going to mess with it anymore today. I guess it will sit for awhile. Maybe I'll just siphon the fuel out 5 gallons at a time and put it in my wife's Ford.

jaunty75

What was the reasoning behind this? It's not easy to do as the ground wire is soldered or somehow directly connected to the sending unit while while the hot wire connects to a terminal on top of the sending unit. There is only one way to connect the wires, and to do it any other way requires violating half the laws of physics.

Of course the gauge will read E all the time as you've now connected the wire from the gauge directly to ground instead of to the hot side of the sending unit.

As frustrating as it's been for you, and I can sympathize, this really isn't that hard. The circuitry is very simple and easy to follow.

The next time you take the sending unit out, test it before reinstalling it. Connect the wire coming from the gauge to the hot side of the sending unit, and connect the other wire from the sending unit to a good ground on the car, such as the rear bumper. Then, while holding the sending unit in one hand, have a friend sit in the front seat, put the ignition on, and watch the gauge as you move the float up and down with your other hand. If the gauge moves back and forth as it's supposed to, the wiring is fine, and you can reinstall the sending unit in the tank.

If the gauge does not move as expected, there is a problem, and it needs to be troubleshot. Observe what the gauge does do (stays on E, stays on F, parks itself in some random location and doesn't move) as that will lead you to the source of the problem.


When I replaced the sending unit on my '67 Delta 88, I took a photo of the old one in place before I removed it, and that photo is below. (That wetness around it is not leaking gasoline. Rather, I had just sprayed it with PB Blaster to loosen the locknut.) I'm guessing the replacement sending unit you have it similar in how it's wired up. You can see that it's not possible to simply swap the two wires as the ground is hard-wired to the top of the sending unit while the hot wire has a plastic-covered connector that can be popped off and on. Swapping them would require major surgery.

oldcutlass

Some of the sending units have a separate terminal for the ground and sending unit connections. When you removed the gauge wire did it go passed F with the key on? If it does, that only leaves the sending unit itself. You can test that theory by hooking up the old one as it worked.

Olds64

Well, eventually I'll take the unit out and troubleshoot it.

I'm pretty lost right now. The new sending unit doesn't hook up the way the one in the picture does. There was a threaded stud on the top that I originally hooked up to the signal wire and then there was a spade connector that I put to ground. When I did that the gauge read below E constantly unless I opened the connection to the threaded stud. When I did that it would go above F.

Now, that I swapped the lines it constantly reads E. There are only two possibilities on connecting the wires. I've tried both. Apparently either my gauge or my unit is bad. I might mess with it again next weekend.

viper5gm

Sounds like the problem is with the new sending unit you installed. The float may have came off the level rod when you were installing the unit and now the level rod is at the bottom. To check the wiring/gauge just take the signal wire off the sending unit and turn the key on and the gauge should read full, if you ground the signal wire the gauge should go to empty. If it does than the problem is with the sending unit and you need to take it out and check for free movement of the level arm and check the condition of the float on the rod

Olds64

Just in case someone finds this thread in a search I'm providing an update. Actually, a recent thread made me search for this one and I've since solved the problem.

I found that the threaded stud on top of the fuel sending unit was grounding to the body of the car whenever I installed the tank. This gave me an erroneous reading even when I installed the wires correctly. I had to remove the threaded stud on top of the sending unit and attach the wire with a machine screw.

I used a nylon lock nut and Loc-tite on the underside of the fuel sending unit to secure the machine screw. I figured the gasoline might damage the nylon in the lock nut, but if I start getting a bad reading again I will know what the problem is.