imcgm

Hey guys, my 1967 Delmont has a gas gauge that just stays at half full all the time. Any ideas? Easy fix? Parts available?

As always thanks for your knowledge

Mike

tru-blue 442

I had a 68 Delmont that did that and I found a replacement gauge for it that fixed the problem.
Not saying this is your problem but it was for me. Fellas will chime in, good luck.

oldcutlass

Your going to have to remove the gas tank wire and with it connected to nothing it should go past full, if you ground that wire it should go to E. If it does neither of these you need to see if you have power and grounds at the gauge.

imcgm

Thanks! I am on Summit racing right now trying to determine which one is the correct one for it… Maybe one of the smart fellas knows that also 😉 ... or a better place to look 👍🏻

imcgm

great advice, thank you!

jaunty75

You want to troubleshoot this before throwing money and parts at it. My guess is that the dash gauge is disconnected.

Do as oldcutlass says above. Separate the wire coming from the sending unit from the wire coming from the front of the car. There is a connector usually around the license plate area. Then ground the side coming from dash gauge and turn the key to ON. The gauge should move immediately to E and stay there. Then remove the wire from ground, and the gauge should go immediately to F or more likely beyond it. If both of these things happen, the dash gauge is fine as is the wiring from the front of the car. The problem is likely then in the fuel tank sending unit or its ground.

The next thing to check is the sending unit ground, and that's up under the car in front of the gas tank. You'll have to crawl around under there to find it. It's just attached to the frame and exposed to the elements, so it could easily be corroded. Make sure its clean and tight and check the gauge again. With luck, this fixes the problem. If not, the problem is the sending unit, and that's no picnic. I don't know what you found at Summit, but no one make sending units for these cars. I have a '67 Delta which also had fuel gauge problems. It has the same sending unit as your car. I removed the tank and sending unit, and below is a photo of the sending unit. It consists of a plastic hockey-puck-like float that rides up and down on a shaft inside a canister. The canister has small holes in it, and the whole thing acts as a baffle to prevent the gauge needle from bouncing around as the car goes over bumps and around corners, causing the fuel to slosh around inside the tank.

I replaced my sending unit with one meant for a '72 Buick LeSabre, which IS made new. It's a drop-in replacement, but it's the float-on-a-hinge style that is not baffled, so the gauge WILL bounce around a bit as you drive. But at least you have a gauge.


This is the sending unit disassembled. The canister fits over the float unit. You can see the tiny holes in the side of the canister. That causes the level of fuel inside the canister to change slowly and prevents fuel sloshing from bouncing the float up and down. I tried to fix mine, but no matter what I did, I could not get the float to slide up and down on the shaft freely. I didn't want to have to drop the tank every few days to free the stuck float, so I decided to replace it. Not shown in the photo is the pickup pipe sock filter, which fits over the bottom end of the pickup pipe. Mine was completely disintegrated, and no replacement was available, which was another reason I ditched this one and bought the new one.




Here's a photo of what the replacement unit looks like. It's made by Spectra Premium, and you can get it at rockauto.com, among other places.




Keep your fingers crossed that your problem is just a bad ground or an open in the wiring. If the system does not pass the initial tests (gauge moving to E and F as noted above), then the problem is probably the dash gauge itself. I have no experience with those.

imcgm

so i finally got some time to work on this. i disconnected the wire in the trunk above the license plate and as advertised the gauge shot up past F. so then i found the ground under the car and cleaned off a spot on my underside, clipped the wire and put a new connector on it with a self tapping screw into the underside of the trunk and as soon as i plugged everything back in my gauge went right back to half full, straight up and down i suppose that means a new sending unit is in my future...unless i missed something?

thanks again everyone!

Mike

jaunty75

You have to do the other half of the test to verify that the dash gauge is working ok. Take the end of the wire that you disconnected above the license plate that comes from the front of the car and ground it. The ignition to ON, and the gauge should move to E. You want to verify that the gauge needle itself moves freely and that everything is electrically ok with the gauge. So those are the two tests. Disconnect the wire with the key ON, and the gauge moves to F or beyond. You've verified this. Now ground the wire coming from the front of the car, and verify that the gauge moves to E. If it passes these two tests, then the problem is at the rear of the car, and, as you say, it is probably the sending unit.

imcgm

Yup, right to E. damn my luck...oh well. am I crazy to think it makes sense to replace the whole gas tank and straps etc as long as I’m taking it out?

oldcutlass

Yes your crazy if the tank is in good shape. Drop it and see whats going on with your float.

jaunty75

Yes, if you can find a tank, but they are not made new for these cars as far as I know. As long as your existing tank is in good shape, the best thing to do is have it refurbished---radiator shops can often do that---and reuse it. That's what I did with the tank in my '67 Delta. It's the original tank, and it's going strong after 52 years and 132,000 miles.

Replacement straps should be no problem, and, yes, I would replace those if you're taking down the tank.

imcgm

Ok, sounds like solid advice. thanks again all. Has anyone found another choice other than the '72 Buick LeSabre option? I don’t really mind if the gauge bounces around but if someone knows of another option I’m all ears 👍🏻

Thanks!
mike

oldcutlass

Jaunty was pretty thorough on his search, his suggestion is from personal experience.

imcgm

So hears an interesting development. I just noticed that I don’t have any dash lights either right now, courtesy lights work but now instrument lighting. Any way the gas gauge not working and the fuel gauge not working are related?

just wondering...obviously I’ll be spending some time under the dash with the wiring if it’s not something simple like a fuse.

thanks in advance all!

jaunty75

I would certainly hope so as "gas gauge" and "fuel gauge" are two terms for the same thing. Proofreading is your friend (and ours, too).


The instrument panel lamps (the ones that light up so you can see the speedometer at night) get their power through a 3 amp fuse connected to the headlight switch. This circuit also supplies the clock lamp, the ash tray lamp, the ignition switch lamp, and a couple of other lamps. The 3-amp fuse is probably labeled PAN. LTS. The gas gauge gets its power through a 9-amp fuse labeled "INST B/U" on the fuse block. This circuit also powers the back-up lamps and the various warning lamps on the dash (HOT, COLD, OIL, GEN, and BRAKE).

All of this is on page 12-5 of your 1967 Olds Chassis Service Manual. You DO have a copy, right?

imcgm

[QUOTE=jaunty75;1179968]I would certainly hope so as "gas gauge" and "fuel gauge" are two terms for the same thing. Proofreading is your friend (and ours, too).

Thanks for pointing out the obvious. Oh and also the advice…

imcgm

well, now i just feel dumb. the fuse labeled inst b/u is empty...so i guess i shouldn't be surprised that my gas gauge doesnt work! thanks @jaunty75 for quoting the service manual for me. but i have to tell you i have no idea what kind of fuse goes in that itsy bitsy spot!

im starting my search for this fuse, but if anyone has a pic or a link to the proper fuse i would greatly appreciate it

thanks again all!
Mike

jaunty75

It's a 9 Amp fuse. I mentioned this above. It's a tubular glass fuse that looks like all the other ones in the fuse block and is available at any auto parts store.

oldcutlass

I don't understand, you stated above through the test of grounding the tank lead and it going to E and having the lead open it goes to F. The gauge was working.