1960 C1 Fuel Gauge

[Joseph U.]

I was unable to start my 1960. No fuel in the filter bowl and gas gauge reads full. Cleaned the filter bowel, checked the lines for cracks, replaced the filter and still with constant cranking was unable to get fuel into the line or the carbs. Was able to put gas in carb and start up - but of course quickly died out as no gas from tank to carbs. Figured it was fuel pump and was going to replace myself - but too hard to get under the car so took it to a local mechanic that I have used before - (he is knowledgable and respects a classic car) - anyway he pressurized the fuel tank and car started - we put an additional 2 gallons of fuel in the tank and car started right up and ran just fine. So obviously tank is not full - probably closer to empty. So the question is the fuel gauge which continues to read full. Does anyone know what the default reading is if the gauge is bad (full, half-full or empty) or if the sending unit in the tank is shot? Or is it possible that the line in the tank has moved and is only drawing off of the top of the fuel level?
Plan to start it up again tomorrow morning - and if it starts I will take it and fill with gas - if it takes 10 or 15 gal then it would seem that the gauge is misreading for some reason. Then question is to replace gauge, sending unit or just monitor milage and fill frequently with gas. Any thoughts would be appreciated as always.
Ahh - the fun of an old car.
Joe

[George W.]

Re: 1960 C1 Fuel Gauge

Most likely the sending unit in the tank is shot; they gum up and the fuel sock won't pickup fuel...that may be why pressurizing the tank pushed
fuel through to the carb. Replacement sending unit cost in range of $80; easy fix, have fun.

[Joseph U.]

Re: 1960 C1 Fuel Gauge

Most likely the sending unit in the tank is shot; they gum up and the fuel sock won't pickup fuel...that may be why pressurizing the tank pushed
fuel through to the carb. Replacement sending unit cost in range of $80; easy fix, have fun.

Thanks George - any way to test to make sure?
Rather not just start replacing stuff.
Joe

[Joseph U.]

Re: 1960 C1 Fuel Gauge

Thanks George - any way to test to make sure?
Rather not just start replacing stuff.
Joe

BTW - how hard is it to replace the sending unit?
Joe

[George W.]

Re: 1960 C1 Fuel Gauge

You have to take the unit out of the tank; lay it on the bench and "carefully" take the float apart, it has 3 crimps holding it together and tends to become solid
with gum/varnish; if you get it clean and back together and the sending unit wire clean and the float cork is ok...it might work; if it does you will still likely be off on fuel gauge reading, i.e. if if works you likely will run out of fuel when gauge reads 1/4 to 1/2 tank; that is why I say replace the unit...you get all new stuff and new fuel pick up sock. This way you only take the unit out one time and the replacement unit comes with new gasket, float and fuel sock. Not hard to do, U can do it.

[Richard M.]

Re: 1960 C1 Fuel Gauge

First thing I'd check is to make sure your sender is properly grounded. A floating ground at the sender could cause high readings at the gauge. There is a black/white tracer wire from the dash harness to the tank sender screw. That may be loose or broken. You could run a jumper from a known good ground and touch it to the bottom of the tank(through a vent hole or clamped to the hard line from the tank, and have someone watch the gauge to see if it drops down.

Here's what you should read when testing the sender. But you really need to remove it to test it. This is the reproduction/replacement.

apx 30 ohms full.
P5050007.jpgP5050008.jpg

apx 0 ohms empty.
P5050009.jpgP5050010.jpg

You either have a full tank and a plugged flow, or a empty tank and a bad sender. Likely the sender is reading high. That's usually how I have seen them fail if the ground is good.

It's a bit tedious to get at it, but here are a few shots of what you'll be getting into. Best to remove the seat bottoms, then seatbacks, lift the decklid and remove the screws holding the tank cover. Remove the cover and the sender will be accessible. Use a flare nut wrench on the fitting while holding the other nut with a wrench.
P5220073.jpgP5220074.jpg

Rich

[Edward B.]

Re: 1960 C1 Fuel Gauge

Let's not go overboard and make this more difficult than necessary by suggesting all sorts of disassembly before performing some simple electrical testing to assure there is a good ground for the sending unit and a direct non-shorted connection between the sending unit and the gauge.

[Joseph U.]

Re: 1960 C1 Fuel Gauge

Thanks,
I agree - need to check the easy stuff first - especially since I just replaced the dash wiring harness. As soon as I get it home I will start the electrical checks first. It does however look like something I can do if I have to. Stuff going on so as always time is an issue - and now that it runs I can monitor the milage traveled and just keep the tank full - but need to fix - just because I like it to be right.

Joe

[Dan D.]

Re: 1960 C1 Fuel Gauge

Joe - make sure that when you replaced the wiring harness you did not get the wires to the rear mixed up. Be very careful here, if you inadvertently put a hard 12V, say from the tail light or brake-light wire on the sender line, that will cook the sender immediately. If the sender resistor is submersed in fuel, it may just boil the gas for an instant until the sender wire burns up. Don't know. But if the tank is empty and the sender is in free air, I have to believe it will explode instantly.

Just advising you to be very careful. The gauge going to 'full' is an indication that the line is open. Either the wiring, or the sender itself. As others have said, check the ground wire first - this is a known problem.

-Dan-

[Joseph U.]

Re: 1960 C1 Fuel Gauge

Joe - make sure that when you replaced the wiring harness you did not get the wires to the rear mixed up. Be very careful here, if you inadvertently put a hard 12V, say from the tail light or brake-light wire on the sender line, that will cook the sender immediately. If the sender resistor is submersed in fuel, it may just boil the gas for an instant until the sender wire burns up. Don't know. But if the tank is empty and the sender is in free air, I have to believe it will explode instantly.

Just advising you to be very careful. The gauge going to 'full' is an indication that the line is open. Either the wiring, or the sender itself. As others have said, check the ground wire first - this is a known problem.

-Dan-

Interesting thought - but if I recall - all of the connections were via plastic Male-Female connectors that only fit one way. Not sure how I would get the wires crossed. And if a wire was crossed - would I not have problems some place else? Maybe I do and don't know about them yet. Anything else you would suggest that I test. Last thing I need is an explosion in the gas tank.
Joe

[Dan D.]

Re: 1960 C1 Fuel Gauge

Okay Joe. I was thinking about that. I was not sure about 1960s, earlier ones had separate wires. Not saying your harness was not built wrong, but I doubt that it is. I think your problem is probably the sender. You need to get it apart to see. It is not hard to do, as has been described to you by Rich.

What I have done is with the sender out of the tank and the wires hooked up (ground wire also), move the float up and down and watch the fuel gauge. The fuel gauge should follow the float position. Also, if you ground the sender wire the gauge should go to empty. These two tests should pretty much isolate just where your problem is.

As long as there is no hard 12V on the sender wire you should be good to go. No explosions wanted, for sure. You have had it running with no ill effects, so you should be good in that respect. Didn't mean to frighten you, but you can never be to careful with gasoline and electricity.

-Dan-

[Joseph U.]

Re: 1960 C1 Fuel Gauge

Thanks Dan,
I was a little concerned but as I thought about it - if it was going to explode it probably would have done so the day after I put 2 gallons of gas in the tank.
I think first step is to just look at connections under the dash and in the rear - who knows - may just see a broken or loose wire and be done. If not then the sender needs to go. no matter what - I think if I have it apart - for $80 or so - might as well put a new one in. The old one has to be - what - 56 years old - looks like the effort goes into exposing the sending unit - not taking it out and putting in a new one. I will check it out as you suggest, so that I know if that is the answer - but will probably replace anyway.
Thoughts?
Joe

[Joseph U.]

Re: 1960 C1 Fuel Gauge

The Plot thickens. I drove the car home without problem and preparing to replace the sender unit - but I wanted to put a little more gas in the car just to be safe. Put in 1 gallon and tank overflows - so in total I put 5 gallons in the car since it started - meaning that the tank was not empty in the first place but had to have about 10 gallons in the tank when the mechanic pressurized the tank and got it running. But even then with 10 gallons the guage was at Full Plus - so wanted to take off a little fuel so took it for a spin - 10 miles or so to a store. Stopped and shopped, another 5 miles to the auto parts store for a light bulb and then started home. Half way home car bucked - but I kept it going - got to within 1 mile of home and car dies. Cannot start the car. Battery cranks, fuel in fuel bowel, but no start - will turn over and fire if I put gas in carburator but will not keep going - put another gallon in tank and tank overflows. Will not start - so get the Tow Home on a flat bed trailor - push the car into the garage, decide to try one more time - and car fires up like nothing was wrong. And fires up again and again and again. I am puzzled to say the least - can't be the amount of fuel in the tank, can't be the fuel pump or the carburators. I know fuel gauge is shot but that would not cause this problem. Any ideas? Is it possible (I know anything is possible, but is it probable) that there is dirt in the tank that is periodically clogging the line - and then gets dislodged when the car is tilted to bring it up on the trailer? Seems wierd but something intermittent is going on here to every now and then keep gas from getting into the cylinders.
Any thoughts would be most welcome,
Joe

[Don H.]

Re: 1960 C1 Fuel Gauge

Joe, It sounds like a possible electrical short. You said there was fuel in the bowl but no start. The next time it won't start check for spark. Good luck, Don H.

[Joseph U.]

Re: 1960 C1 Fuel Gauge

How would I do that Don?