CLASS DISMISSED... FUEL GAUGE QUESTION

[Sir reel]

The fuel gauge in my Carolina Skiff has had a problem for nearly a year. When the power is off the guage reads empty. When the key is turned on, the gauge jumps to Full, regardless of the level of fuel. The gauge never moves just stays on Full. After discussing the issue with a few folks who know more than I do about it, the general consensus was that the Gauge was OK and it was most likely the Sending Unit. I disconnected everything last night and pulled the tank then removed the Sending Unit so I could match the screw holes and configuration of the float. Took off at Lunch, purchased a new Sending unit with same screw pattern and correct arm lenght. When I got home, I installed the new Sending Unit, reinstalled the tank, put in about 6 gal. Turned on the key and the gauge still pegs to Full regardless of the fuel level. Most of the sources that I spoke with said that if the gauge went to full when the key was turned on, it obviously had power and was working if it went back to empty when power was turned off. SO... lets hear some discussion as to whether it is the gauge after all and how best to determine/verfiy it's the gauge because I've already apparently replaced a perfectly good Sending Unit. READY... SET... GO! I'll check back tomorrow... you folks have a good day at Rocky's tournament

[Steve Stinson]

Normally if the gauge pegs at full its a grounding problem. If it never rises, its a power problem.
-Steve

[Flint River Pirate]

Somebody on here was discussing that a few months ago. Maybe someone will chime in.

[tin can]

You can test the sending unit and gauge with a multimeter. The gauge is measuring the current from the sending unit. Lets assume the sending unit is good (since it's new). Pull the sending unit out of the tank. pull the wires loose at the gauge. Hook a meter to the wires at the gauge end. Manually move the float on the sending unit. If the meter changes,its a bad gauge. If it doesn't change start tracing wires and find the short.

[SS-342]

Tin Can nailed it!

I had mine to stick inside the tank on the full position. I would think after taking it out and replacing with a new one and not having a full tank that this would not be your problem. If you don't have a volt meter, seem it would work to take it out of the tank, hook everything up and do the same as Tin Can suggested looking at your meter on the boat.

What I found dumb founding was that the holes in the top wasn't all the same distance apart. Mine would go back only the original way and it was positioned a little off.

Mine works but I always look at the tank instead of the gauge.

Hope you get it fixed. It is annoying to have something that is out of order.

[killswitch]

I just went through some issues with sending unit/fuel gauge a few weeks ago. Actually have a post on here about the issues.
Also got some valuable info from teleflex web site. Hope it helps.


Here is test info from Teleflex's web site



The Teleflex fuel gauge and the level sender are designed to operate on 240 ohms (empty) and 33 ohms (full). Most other manufacturers build a marine fuel level system of the same resistance as gauges and senders may be mixed at the boat builder level.
There are only three components to the system-gauge, level sender, and the connecting sender wire. The sender wire should be inspected for breaks in the copper or corroded connection to the terminals.

The fuel gauge can be inspected in the following manner. Turn the ignition on. Remove the sender wire from back of gauge. Pointer must go below the empty mark. Next, connect the gauge sender terminal to ground. The pointer must go above the full mark. If the pointer moves past both E and F, the gauge is functional.

To check the fuel level sender remove wires from sender terminal. Connect volt/ohmmeter to two sender terminals (digital ohmmeter will tend to be jumpy). Ohmmeter should read approximately:

1. 240 ohms @ empty
2. 100 ohms @ 1/2 and
3. 33 ohms @ full.

If the sender is not sized properly for the tank, errors in gauge reading can also occur

[Fighting Conch]

Hey SS-342. I may be off course on this but does your handle refer to the USS Chopper? That is the sub that accidentally went full dive off of Cuba to under 1,000 feet and somehow survived. My ol' Navy Dad used to talk about it, among others he spent time on SS-320, the Bergall.

[Sir reel]

OK Boys and Girls...Class is back in session, please take your seats.

I would like to report the following:

I followed the instructions that killswitch provided as they seemed to be the most straight forward and did not require me to remove the tank so I could take the Sender Unit back out. In addition they pretty much combinded the guidance provided by TC.

The fuel gauge... Turn the ignition on. Remove the sender wire from back of gauge. Pointer must go below the empty mark.
I preformed the above test and the Pointer went below the empty mark.

Next, connect the gauge sender terminal to ground. The pointer must go above the full mark.
I preformed the above test and the pointer DID NOT MOVE. However, I grounded the gauge to the ground on the fuse block. When I ground the gauge to the Tank, it does move to the full mark

NEXT, I went ahead and checked the fuel level sender as follows:
remove wires from sender terminal. Connect volt/ohmmeter to two sender terminals Ohmmeter should read approximately:

1. 240 ohms @ empty
2. 100 ohms @ 1/2 and
3. 33 ohms @ full.

Here are my results: 18 gal tank With approx 6-7 gal in tank ohmmeter read 132
I added another 6 gal to the tank and took another reading with approx 12-13 gal the ohm reading was 52.
Based on these readings it would seem to me that the Sending Unit is working properly and can be rulled out as being a problem. The question I have now is, can we say for sure that it is the gauge or can there still be a probelm between the gauge and the switch? When I ground the gauge to the tank I still get the full reading but follwing killswitch's test it would indicate the guage is faulty?

[Jumptrout51]

Bad gauge.

[robbankston]

Bad gauge.

I agree. If you wanted to do a test you could always take your gauge loose, hook up your multimeter and check the ohms there. If it is getting a good reading it's definitely the gauge.

[tin can]

What robbankston said.

[Sir reel]

It is with great satisfaction that I'm please to report that after today's purchase of a new gauge and the subsequent installation... we now have a working fuel gauge

Boys and Girls, you've been a wonderful class and you should be very pleased with your participation. Considering who you've had to work with, you did an outstanding job of working through the issues, providing direction at the level necessary for the worker to accomplish the task, and exercising extrodinary patience. Thanks to all of you and to the staff and management of this fine institution for the most valuable resource we have to enjoy. Never under estimate the power To TC, Killswitch, Jumptrout 51,robbankston, SS-342, and Skag Thanks and GOOD JOB.

[robbankston]

Glad it worked out!

[killswitch]

good deal...........

[wevans]

It is with great satisfaction that I'm please to report that after today's purchase of a new gauge and the subsequent installation... we now have a working fuel gauge

Boys and Girls, you've been a wonderful class and you should be very pleased with your participation. Considering who you've had to work with, you did an outstanding job of working through the issues, providing direction at the level necessary for the worker to accomplish the task, and exercising extrodinary patience. Thanks to all of you and to the staff and management of this fine institution for the most valuable resource we have to enjoy. Never under estimate the power To TC, Killswitch, Jumptrout 51,robbankston, SS-342, and Skag Thanks and GOOD JOB.

HEY, WHAT ABOUT ME I stayed out of it glad it's workin again fer ya