Fuel Gage Woes
 

I have searched here and on the Chevelle website, and looked at a number of youtube videos on the subject......and I'm still unclear on the problem I have.

The problem: all of a sudden, the gas gauge on my 69 Chevelle (which had been working only half-assed accurately) went to WAY past full and stayed there. Did some tests based on reading past threads and looking at youtube videos, and best guess was that the sending unit went bad. So, I dropped the gas tank and pulled the sending unit out. Using an ohm meter on the sending unit, I find that at the low point of the float (i.e., empty tank) it reads 10 -15 ohms. Moving the float to the high point (full tank), it reads 120 - 125 ohms. When I take the sending unit and hook it up in the trunk of the car with the tan wire (from the gauge) connected to the sending unit and the ground wire from the sending unit to a good ground in the trunk, moving the float on the sending unit through its full range of motion (with the ignition switch on) has no effect on the pointer on the gauge....it stays WAY past full. When I completely disconnect the sending unit, and just ground the tan wire from the gauge, with the ignition on, the gauge moves perfectly to the 'E' mark. Unground the gauge with the ignition on and it returns to WAY past full.

Any ideas?

Bill is that sender new? Perhaps Rick will chime in....did Rick replace that sender?

Dan

No, sender certainly appears to be original. Someone has had the tank out of the car before, with resulting damage to both ground wire and gauge wire....both poorly repaired. No insulating material between tank and trunk floor either, although you can definitely see evidence on the tank that it was there originally.

Well that rules out a bad new repop sender.....very typical what you are describing. I assume you cleaned the ground and installed a new star washer.

Dan

Sender is definitely not a repop, as it says "AC Made in USA" on top. The end on the ground wire has 'teeth' on the opening for the screw, so it needs no star washer....and yes, it's a good ground.

I never had any problems with the gas gauge, and never had the tank out.
Check the plug-in of the rear harness where it meets the intermediate harness and all other connections to make sure nothing is corroded or loose.

This will take a few lengths of wire -- but bypass all the OE wire connections in the car ... run new wire from gauge to sending unit. Also, make sure there is voltage at the gauge. Good luck!! TAZ

If you need to have the original sending unit rebuilt, John Wolf & Co. Inc. in Willoughby, Oh. is your man!! They do excellent work. They just rebuilt my original sending unit for my Impala.

Rich

Definitely voltage at the gauge, since it moves as I described above. And there should be no issue with the tan wire from the gauge to the sending unit, since when I ground that wire back in the trunk, the gauge moves from past full all the way to empty. If there was a break in that wire, I would think that would result in no movement of the gauge.

Rich, thanks for the lead on a rebuild if that's what ends up being necessary.

The problem with the sending units is usually it looses contact where the wire hooks on to the sending unit. Check continuity from the stud where the sending wire hooks up to the sending unit itself. The connection where it goes from one side of the sending unit to the other side goes bad. You can t6ake it apart and clean it

Correct. In a few cases where I have been assisting troubleshooting gage woes the above is the case. EVEN with brand new tank brown replacement wire assy's. The female connector that slips over the stud lacks sufficient tightness to maintain consistent electrical contact and continuity. Some corrective actions are; clean stud on sender with contact cleaner and polish brass with craytex or equal abrasive, Same with female connector and also pinch the barrel of the female connector with pliers but not to much & test fit, I use silicone grease or better yet T&B conductive grease Koper-shield (just a dab) before making the connection.

Additionally I built a "SIMULATOR" tester to validate the body & dash & gage wiring by installing a hand held 0-100 ohm potentiometer to dial a gage where you can sit in the car and run the knob up and down and watch the gage repeat.

JIM

Great ideas, thanks to all who have responded!

Bill what I was talking about is where the stud goes thru the sending unit there is a insolator and a strap that goes down to the sender resisitor. The connection from the stud thru t6he mounting plate goes bad. There is a push clip that holds it together you take it apart and clean it

I will give that a shot, John....thanks!

OK, it's definitely a sending unit problem. I bought a repop sending unit and it arrived today. Hooked it up in the trunk of the car and moved the float through its range of motion, and the gage reads perfectly.....'Empty' when the float is at its lowest point, and 'Full' when it's all the way up.

Of course, since we are talking about repop parts, nothing is quite right....all appears good except for the ground wire. The ground wire is connected to the sending unit body pointing in the wrong direction - AWAY from the direction it should be going. Plus, the wire is about 4" shorter than the original one, and since one would need to use additional wire length in order to route the wire in the proper direction, that makes it effectively shorter yet. I mean, really, all the engineering involved in making this thing otherwise a very good copy of the original and you screw up two SIMPLE details like these? No wonder so many repop parts have a bad reputation.

One American dollar says if you contact the repop company about their short comings,they'll reply,"You're the first person to tell us this Mr.Pritchard."

I would bet that same American dollar that you are 100% correct, Rick!

Well, I tried John's suggestion about taking the hot wire connection apart to clean it, but it seemed like I would destroy the whole works before it would come apart.....so I took Rich's suggestion, and sent it off to John Wolf & Company in Willoughby OH for restoration. Got it back today and wow.....it looks like new....

Hooked it up in the trunk (as I detailed in a previous post in this thread) and it works perfectly. And whaddayaknow, the ground wire is long enough to connect to the proper location on the car. They also reused the original ground wire terminal end so the appearance is as close to OEM as possible. Now all I need to do is order a 'sock' type filter for the end that goes in the tank and it will be ready to go back in the tank.

I found this thread to be helpful on my 69 Z:

http://www.camaros.net/forums/19-ele...n-69-pace.html

mine had issue where the ribbon connector connected to stud that went through the sender to the wire figured since had at worst to buy a new sender, so I bent the ribbon and got continuity and been fine since fixed no cost but my time

I had a very large reproduction parts house tell me that one time so I directed him to a Team Chevelle thread where they were talking about the same complaint as mine and with their product and there were at least 10 complaints exactly like the one I was talking about. He did not have much to say after that but was still not willing to make good on it. I said they could either stand behind their product or I would add to the thread on Team Chevelle. The worst part was I spent at least $50k a year with this company, every year, which I no longer do. Their loss.

There's no way that I am the first person to notice this ground wire problem on the repro sending units.....anyone else who has complained has probably been given the brush-off like I got. But undoubtedly the majority of the buyers just kept quiet and found somewhere else to hook up the ground wire, and as far as I'm concerned all that does is give the manufacturer license to continue business-as-usual. And as Rick says, I won't do that either.

New 'sock' filter....