View Full Version : fuel guage misreading

07-04-2006, 12:07 AM
When my tank is full my gauge reads 1/2. When it's about 1/2 full it reads 1/4. What can I do about this.? I just purchased this boat last week.

07-04-2006, 01:43 AM
Wish I could help you, but I can't. If it makes you feel better, my 92 PS 205 shows full no matter how much fuel I have. The guys will probably ask you info on you boat to help them give a better answer... year...model...

Good luck

07-04-2006, 06:50 AM
ground the signal wire from the sender, the gauge should peg full.
if not you probably have a gauge problem, all other gauges working ok ?
then fill your tank and check the ohms reading from the sender.
let us know what it is . a boat yr and model would be of interest also.

Jeff :headbang:

07-04-2006, 08:23 AM
Probably the sending unit, go ahead and change it out and get it over with. www.skidim.com has replacement units and there are other resources that someone will post when they see this thread.

07-04-2006, 08:55 AM
I'm also the proud owner of a "new to me" MC and I'm trying to "unravel" the quirks of the previous owners "repairs". The fact that your gauge moves, but is off by a factor of 2 makes me thing a replacement sender was installed incorrectly (or was the wrong sender for the gauge). Haven't played with my MC sender yet, but in other boats I've owned the float in the tank is on an arm that you cut to length and bend to fine tune. You might want to play around with it (nothing to lose).
If you decide to replace the sender, chat with the guys at Skidim when you do. They helped me with a couple of issues (like, where's my thermostat?). If your gauge isn't original, have any identifying info handy.
Sorry I wasn't that helpful, but this was my first shot at contributing to the board rather than just asking questions.

07-04-2006, 09:09 AM
For both Boyd and 123SRC it sounds like the sending unit is the issue as others have suggested. I am not certain about the 1991 Prostar tank in Boyd's boat, but I used to have a 1992 205 like 123SRC's, and the sending unit was mounted inside a vertical tube to keep the gauge from bouncing around when the fuel slooshed. I had the exact same issue with the gauge sticking, and found that the float inside the tube had swelled and was stuck. The easy fix is to replace the sending unit, but instead, I pulled it apart and sanded the float down so that it no longer got stuck. The sensor was basically a "Hall Effect Device" which essentially uses a magnet and a sensor to determine position. The magnets (one on each side of the float) were glued into the float. In the process of sanding it down, the magnets got knocked out, and I found that depending on where I put them back I could change the gas gauge reading. I was able to play with them with the sending unit out of the tank and determine where they needed to be to make the gauge read correctly. Then I glued them back in place with a gasoline resistive glue. I do not remember what I used, but I do remember the first time the gauge quit working about 2 months later because the glue did not hold. I took it apart, and reglued with something else, and the gauge never gave me another problem for years. The easy fix is to replace the sending unit, but if you are like me and don't mind taking things apart, the gas tank does not need to be completely removed, just slid part way out, and the sending unit is easily accecible through the top of the tank.

Good Luck.

07-04-2006, 09:17 AM
I believe there area also instructions on how to clean/maintain the sending unit in the 1992 PS 190 manual.....might want to look there and see if that'll work for ya. If not, the next step is probably a call to SKIDIM...they may be able to tell you other things to check before dropping the $$ on a replacement. Those guys are great with phone support and deserve the business when you do need replacement as the advice is always free.

07-04-2006, 06:17 PM
Thanks a bunch. I'll call skidim. I wouldn't know a sending unit if someone through it at me. Where is it?

07-04-2006, 06:34 PM
Thanks a bunch. I'll call skidim. I wouldn't know a sending unit if someone through it at me. Where is it?

It is in the top of the tank and goes down about 12". It takes about an hour to change out. You can do a quick check to see if it is your guage or not by tuching the two leads together that screw into the top of the sending unit. If the guage pegs to full then it is definately the sending unit. I replaced mine (94 ps190) with the one from SKIDIM and it works great.

07-04-2006, 07:16 PM
So .... I have to take off the brackets and slide the tank out ??

07-05-2006, 03:55 AM
Thanks for the info. I have never really cared about the fuel gauge too much because I could just slide the rear piece down, bang on the tank and see the fuel level. With your explination, it doesn't sound that difficult to fix. Sounds like a good rainy day project!

07-05-2006, 04:33 PM
I found it in my owners manual. Thanks for the help. Looks pretty easy to fix, but not too cheap. $75. I may just keep filling it up prior to each outing til this winter. THanks again for the help.

I Love this forum.


east tx skier
07-05-2006, 04:36 PM
I would've guessed the sending unit. I believe (but I could be wrong) that the $70 unit from skidim is the improved design. I'm several seasons into my new one and (knock wood), not having any further issues with inaccurate readings.

Kevin 89MC
07-06-2006, 10:10 AM
I was going to ramble on about replacing my sender, but realized it's different than the '91 and up MC's. I will add that I was able to slide my tank out when it was over half full without too much trouble. Finding the old bracket mounting holes in the carpet was probably the hardest part of the whole job. Good luck.

07-06-2006, 02:43 PM
My gauge reads that it is much fuller than it is really. I have maybe 1/4 of a tank left and it reads 3/4 full. Any tests or calibration I can do? 2003 X2