Gas Gauge Problems - 1985 Chevrolet Caprice Classic

On a full tank, the gas gauge only reads 3/4 full. This has been going on for several years. In prior videos, I replaced the gas gauge with a new old stock OEM gauge, and also replaced the fuel sending unit. Neither fixed the issue. This video shows some troubleshooting attempts to diagnose what’s causing this. I think I’ve narrowed it down to a partially bad ground somewhere up at the front of the car between the instrument panel and the fuse box. But I’m still not sure. Please let me know if you have any thoughts or suggestions on this. What a gremlin....
UPDATE 2023: Gas gauge finally fixed. See my video here: • Gas Gauge Finally Fixe...

[@majkiboy86]

I have an 86 but have exactly the same gauge and same issue. Fun fact that when it got colder a bit it fixed itself for a few miles and it fall back again. So happy that i have found your channel as pretty much you have fix for every issue i have :)

[@LongologoProductions]

@majkiboy86: Thanks! Happy to hear that my car isn’t the only one with these issues!

[@ReCkLeSsErr0r]

I think I may be able to help. Since I own a '84 Pontiac Bonneville, it had a similar issue where after the sender unit was replaced by the GM dealership, here in town- and the gauge still did not work. It turns out that the factory wiring was damaged. It is a tan wire. However, I could not locate the actual break itself. Also, there was corrosion on the traces, that run along the back of the gauges as well. I directly had to solder a 10 foot jumper wire, to the back of the gauge itself, and run it along side the car, behind the back seat all the way to the trunk lights, and from there, clip the white wire from the fuel tank, from the factory wiring and connect it to my new bypassed wire. However, in the case of my Pontiac, it has 2 idiot lights and 2 gauges, in a combined cluster. Yours will operate the same, but the procedure to solder would be different.

[@LongologoProductions]

@┗(-_- )┓TURNT : Thanks very much. This is very helpful. I already replaced the fuel gauge and the sending unit, and figured the problem lies in the ground through the frame somewhere, or in the wire behind the gauge down to the fuse panel, or from the fuse panel to the frame. One of these days I will probably end up running a very long jumper wire to test it out like you did, to see if I can isolate a segment of the wire. Thanks again!

[@ReCkLeSsErr0r]

@@LongologoProductions No worries :) I'm sure you will find a solution. Since I posted that comment, I ended up also getting a 1988 Caprice. If you have more videos on these vehicles, I'd really appreciate any further insight. Cheers man.

[@LongologoProductions]

@┗(-_- )┓TURNT : Cool. Composite headlights on that one, right? I'll add more videos on the Caprice, but I've got a lot going on right now so it will be awhile. Rear end light bulb replacements, wheel restoration/repaint are on my to-do list.... Enjoy the '88.

[@ReCkLeSsErr0r]

@@LongologoProductions That they are. I kinda like the lights the previous years had, but at least they work haha. And no worries dude.

[@lytleric]

Awesome video and so glad I found your channel. I just bought a 1983 Caprice Estate wagon and man does it have a lot of problems -- one of those being that the gas gauge is off. The needle reads way past the full mark when full, doesn't start to move until after about 100 miles, and then reads about 3/4 full after more than half the tank has been consumed. Any suggestions from your experience? Should I start with replacing the fuel sender? Will be working through all your videos so thanks for making these -- they are a tremendous resource.

[@LongologoProductions]

@Richard Lytle: Thanks! The gas gauge in my case seems to be an electrical ground problem. I replaced the gas gauge and the sending unit to no avail. Next step will be to replace or splice the ground connection wire from behind the gas gauge down to the fuse panel. Just haven’t had time. If your Caprice has a lot of problems I would suggest prioritizing from big headaches to small headaches (in terms of cost and impact to usability of the car). To me, the gas gauge issue has been a minor nuisance for several years now, and one of those things I know I need to get back to, but other more important things come up (like the need to replace the tires and the shocks). So if it were me, I would save the gas gauge for later, and just keep track of your miles between fill-ups on a piece of paper in the car - probably 200 to 250 miles per fill-up should be a safe estimate. Keep me posted on your progress…. I will post more videos as I have time and continue to work on the car. On deck this year will be the carburetor, speedometer squeaking, and who knows what else….

[@DominiAeternum]

I developed nearly the same problem. The gas gauge will max out only at 3/4 while it used to go all the way when full. Thought it was because I tripped or hit something while cleaning the dash and gauges with the glass screen off. Guess not since this seems to be a common issue. It still drops down normally as I use more of the fuel and the tank empties down below 3/4.

[@LongologoProductions]

@Max Ax: At least I’m not the only one! Still haven’t gotten back around to fixing this yet. See the other comment and @TURNT’s suggestions.

[@cmscms123456]

How did you get your hand behind the speedometer to disconnect the cable? I can't reach...??? Help..

[@LongologoProductions]

@cmscms123456: Starting at 5:20 in another video (kzbin.info/www/bejne/d4OWpX1ujZl4edE), I explained and showed how to reach behind the instrument cluster to reconnect the speedo cable. Also, starting at 3:42 in another video (kzbin.info/www/bejne/r5LWo3imiKmcarM), I explained how to reach behind and disconnect the speedo cable. And, at 0:49 in another video (kzbin.info/www/bejne/g2S9coGjZ96aqpI), I also explained how to reach behind to reconnect. No matter how you slice it, it’s an awkward and tight spot to reach in behind the instrument cluster. I suggest pulling the instrument cluster forward and down a little bit so that you can look down from the top and reach in from the top as shown in the first video link above. Good luck.

[@officiallajames3875]

Where did you get that book from?

[@LongologoProductions]

@Official LaJames: My father. But it’s the standard shop manual. I think this is an example: www.amazon.com/dp/B00435G3QS/ref=cm_sw_r_cp_api_fabc_C7GPFbC0SV5MX

[@officiallajames3875]

@@LongologoProductions 🙏🏿 thanks

[@waheebnatto3778]

I have the same problem in my car its 1989 caprice I have tried somethings but it doesn’t work please let me know if you fix it

[@LongologoProductions]

@Waheeb Natto: Still haven't fixed it. Need to troubleshoot the ground connections all the way to the front end now....

[@ReCkLeSsErr0r]

It's easy to fix, but it does require soldering unfortunately, unless its strictly just a sender unit gone to shit tbh.

[@Mr_kapeli]

I have Changed Gas thank both of my GM cars 1989 Chevrolet Caprice Wagon and 1980-Oldsmobile cutlass calais and the problem is the fuel gauge shows it overfilled like 10 gallons in both cars so how I can fix it becouse I need To get it working becouse its my first car and I am going To 100 mile trip To my friends at summer so it would be nice if i am not out of gas at side of road

[@LongologoProductions]

@Mr kapeli: I have a recent video in which I finally fixed the gas gauge. See kzbin.info/www/bejne/d4OWpX1ujZl4edE.

[@boxchevypat6346]

Did you fix it?

[@LongologoProductions]

@BoxChevyPat: Not yet - haven’t had time and quite honestly I’m not looking forward to taking apart the whole instrument cluster again (see other video). But I think it’s a problem somewhere from behind the gas gauge itself down to the fuse box. See earlier comment on this video by TURNT below for a possible clue too. Separately, I was driving the Chevy last weekend and noticed the gas gauge would randomly swing from 3/4 full to way past empty in less than a few seconds, then five minutes later it would swing back. Not connected to road bumps etc. from what I could tell. Definitely a bad wire or connection. I just have to find where it is. Ugh.

[@boxchevypat6346]

@@LongologoProductions thanks

[@ScottFreeFilms]

Same problem 1989 caprice limo but on propane!

[@elchales1ify]

Did u find out what it is

[@LongologoProductions]

@Tony Pena: The gas gauge in my case seems to be an electrical ground problem. I replaced the gas gauge and the sending unit to no avail. Next step will be to replace or splice the ground connection wire from behind the gas gauge down to the fuse panel. See also comments by TURNT, who suggested this. I hope to try this soon….

[@laashep]

Did you fix it ?

[@LongologoProductions]

@LAA SHEP: Not yet - haven’t had time and quite honestly I’m not looking forward to taking apart the whole instrument cluster again (see other video). But I still think it’s a problem somewhere from behind the gas gauge itself down to the fuse box. See also the other comments on this video by @TURNT. Separately, when driving the Chevy I have occasionally noticed that the gas gauge would randomly swing from 3/4 full to way past empty in less than a few seconds, then five minutes later it would swing back. Not connected to road bumps etc. from what I could tell. So definitely a bad wire or connection. I just have to find where it is. Ugh.

[@laashep]

@@LongologoProductions will keep that in mind! preciate the reply, happ new year !