farking gas gauge... HALP!!!

okay, it's 8:30am on a sunday. i'm at work, dead tired, and grumpy from only 6 hours of sleep after a 16-hour shift yesterday. i'm sure there's another thread about this somewhere, but i'm too short on time and too tired to look for it right now.

forgiveness plz?

anyways, the gas gauge on my CJ5 is a pile of ****ing garbage. the PO installed a NOS ... um ... cluster? (you know, the stock speedo/temp/fuel gauge that's like 2138472134 inches in diameter?) about 1000 miles before i bought it, so i'm furrowing my eyebrows in the direction of the fuel level sender.

here's what it's doing: After filling up, it reads 3/4 full. when the gauge reads empty, there's still about 4 gallons left in the tank. :? a couple months ago, it was showing full when the tank was actually full, but still doing the false empty thing. i drive around town a lot, and have already ran out of luck (gas) once and it was a pain in the ***. knowing how much fuel i actually have would make me an extremely happy camper. few questions...

is this a common problem on older jeeps?
is my sender worn out and need replacing?
can i take it out, clean off the all the contacts or something and it'll work better?
if this is a design flaw with the OEM part, does anyone make a "fixed" one?

thanks for any input/help/advice, and again sorry if there are buttloads of these threads around and i just made a new one.

-Tony

 

no ideas?

 

luckily, i haven't had to deal with this problem but from what i've read is that it's most likely the sender's ground. make sure it is grounded properly...

 

i use a stick poked down the gas hole....

 

yup i use a paint mixer with a full mark on it check it every few times i go out

 

There has to be a good ground from the sender to the body/frame/battery. Intermittent operation could be a bad ground.

The sender itself is nothing but a variable resistor, and is easy to test. The FSM for later model Jeeps gives resistance values for full, 1/2 tank and empty. If you sub those values in place of the sender, that's what the gauge should read.

 

I've been told by Jon Compton at Border Parts (jeep expert from his lifelong college buddies that became Jeep engineers back in the beginning), that if the gauge needle bounces, it's the ground issue mentioned in previous responses, but the bad read issue is a mismatch in ohms between the sending unit and the gauge. He could tell you which each needs/sends, but it occurs when someone replaces the fuel gauge sending unit with an aftermarket unit, the ohms don't match the original Jeep gauge. There was a tech article on the fix with photos, I believe on a Willys website, that showed the sending unit needed an additional short coiled length of wire soldered to the inside. I'll try to locate it, and post the link. It is a simple and easy fix, once ou get the seat out of the way to remove the sender. --Mike

 

my guage reads similarlly but my float is a medicine bottle, because the original float... didn't.
i suggest taking a flash light and look at the boyancy of the float it should be visable from the filler hole.

 

Always carry 5 gal on the back even on a good day these guages are a guess.

 

I had fuel gauge problems in my 01 Chevy pick up. Had to replace fuel sending unit. Talked to a mechanic and he said they are adding alcohol to gas now and it is affecting seal and hose in the fuel system and anything rubber. Could this cause the problem.

 

Go back and read what CJmike is saying. Forget the "I once had a....." comments. Besides, if John at Border Parts says so, I believe it. That guy has an unimaginable breadth of knowledge.

 

What is wrong with just bending the float arm to match fuel level? Sure it is trial and error but we are talking about a Jeep.

 

that would be awesome if we could dig that up. i'll see if i can find it too, but i'm at work now, supposed to be working, so i don't know if i'll be able to find it.

 

wouldn't an already made resistor work? maybe easier to splice in the sender wire than having to solder something on the sender.

i had to do this to my temp sensor. i took some benchmark temperature measurements of the coolant and compared it to what it is registering on the gauge, then installed a resistor in-line of the sender wire.

 

Stewart Warner still sells a sender that will fit in a under seat tank that matches with new guages. Fine tune it with a little strategery bending and it can be spot on. But I still always carry 5 on the back.

 

its the ethenol that does it and theres no getting around it all new gas has it. But if your carb has been recently rebuilt and hoeses and stuff are somewhat new it should be alright

 

One wooden ruler shows level at aprox. one gallon per inch. Crude but what the heck... until I become smarter on sending units, this will work.

56 Willys CJ5

 

R) fair enough. it's not like getting to the filler neck is hard or anything. hell, you can do it from sitting INSIDE the thing.

 

bump.

Can anyone with a pre-1970 FSM tell me what the ohm range is for the V6 sender (under-seat tank).