fuel gauge reading wrong

[cobra25]

I have a new CSX and when the fuel tank is full the fuel gauge reads a little over 1/4 tank. I checked all the wires and fuses and everything seems to be connected.

Any ideas from the world of experts?

[Danr55]

Sounds like it needs to be calibrated to the tank. I'm having the same issue with my car. If I find out how to do it, I'll let you know.

[Slow Dawg]

When we have a fuel gauge problem, 99.9% of the time it's the sender. Pull it out and move the float up and down while someone else watches the gauge. It is either sticking or something is in the tank obstructing the float, like foam in a racing fuel cell or the top of the tank may be bent up or down.

[Slow Dawg]

Hmmm, apparently CS making money through lawsuits and not offering warranties on new csx cars.

[cobra25]

Originally Posted by Slow Dawg

Hmmm, apparently CS making money through lawsuits and not offering warranties on new csx cars.

Oh no, thats not it at all. I am sure if I ask they will fix it! I had a previous issue and my dealer was outstanding! I just thought if it was an easy fix, I would tinker with it myself.
It has a fuel cell so I bet the sender is a little to close to the foam.

[Rick Parker]

If the ohm rating of the sender and the gauge are not the same (usually 240 ohms) it could potentially cause this issue.

[mickmate]

Did it ever read full or it only has ever gone to the 1/4 full mark? Sounds like a possibilty with the float being obstructed. Dan I have some good calibration instructions for the guages if you need a copy.

[cobra25]

It never read past the 1/4 full mark.

[JGSA]

I'm no expert, but I'm having the same type of problem with my CSX. To the best of by knowledge It is a Fuel Safe racing cell with a fuel sending unit manufactured by Centroid. The unit does not have a conventional "float" but works on the basis of measuring capacitance of the fuel within the tube. There are some excellent instuctions on calibration on thier website http://www.centroidproducts.com/fsafe.htm. The kicker is that the length of the sensor tube within the tank does not run from top to bottom, but enters somewhere near the center of the sidewall of tank. Therefore once calibrated, the gauge indicates the tank is full while the sensor is fully immersed. The tank may be close to half empty when the sensor just begins to become exposed and change the reading on the gauge from the full mark. How accurate the gauge reads from this jump from a "full" tank to the actual level is beyond me at this point. I calibrated the sending unit as per instructions, both empty and full. When I begain to fill the tank a second time, it read 1/4 tank with only 1 1/2 gallons of fuel in a 23 gallon tank. Go figure. IMHO the placement of the sensor, and the shape of the tank prevent an accurate reading. For now I'm keeping an eye on the gauge, and keeping an extra 2 gallons in my trunk until I figure this out.

[mickmate]

Do you have a 4000 car? I just looked at one of their tanks with a Centroid sender in the front of it. When I looked at it I just assumed it must be bent or angled down or as you say it won't read anywhere near accurate. There's plenty of room to put senders in from the top even if it's in a recess. At least it will have half a chance to read accurately then.

[JGSA]

Yes it's a 4000 series, the sensor is bent down 90 degrees. I don't know why they did not design the placement of the sensor as you described. Makes sense to me. At this point I don't know if its worth the hassle of modifying the tank and internal bladder. Time will tell. Thanks for your recommendation.

[cobra25]

I called my dealer and they told me it there is an adjustment screw on the sender that needed attention. I found the little screw and a 1/4 turn fixed it.
Just an FYI for you 4000 guys.

[65cobra1]

Do you know if that adjusting screw is only on the CSX or on other models also?

[mickmate]

It's on the Centroid inductive tube senders, both two and three wire. You set one screw to read empty when it's dry or out of the tank, the full screw I have adjusted with the wires hooked up and submerging the tube in a gas can. Now it's calibrated without having to play with a tank full of fuel. You smell a lot better when you come in from tinkering time that way. Peter at Nisonger is very knowledgable on these things if you have questions.

[twobjshelbys]

Mine is the opposite problem. It stays on full and then suddenly jumps to almost empty, and also bounces around wildly when it finally gets off the F mark. It was still on Full on Sunday when it took 14 gallons. When it got off Full a week ago it took 20 gallons. Supposedly it is a 23 gallon fuel cell setup. I saw the gauge connection but didn't remember any adjustments.

[cobra25]

Mine had 2 yellow screws that took a very small phillips screwdriver.

Thanks Mic for the info on how it works now I have a better idea about the two adjustment screws. So, mine registered almost empty when full of gas. When I made the adjustment, I turned the "full" screw.

We'll see how that works.

[mickmate]

Bending those things boggles me. The position of the tube on those 4000 tanks is below the full level from the git go. The Centroid web site talks all about how to order a bent one, bend one yourself etc.

[rokndad]

JGSA and Nick (Mickmate) are on the right track. The Centroid sender side-mounted on CSX 4000's, with a bent tube in the tank, require very, very precise adjustments on the sender's two screws for Full and Empty. I had to use a screwdriver used for fixing eyeglasses. However, with the geometry of the sending tube, you'll never get a smooth transition from Full linearly down to Empty.

After many adjustment sessions with wifey in the car calling out the needle movement, the gage goes to Full with about a half tank (11 gallons). Once it moves off the Full mark, I know I'm about half a tank, and have about another 100 miles or so left of driving before having to look for a station. The needle bounces around a bit under acceleration, then returns to the reading after staying at steady speed. Trial and error is the only real way to get it calibrated. Just have to get under the car to do it. A lift helps!

[mickmate]

Hey Tom check your private messages. Any progress on the fuel at the other end of the system?
Cheers Nick

[ray humbel]

where are these two little screws exactly?