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woodrowskis 05-29-2013 01:52 AM

Fuel Gauge inacurrate
2002 Mastercraft 197:
I am about to search history again but did not find the advice I was looking for last time. Anyway fuel gauge reads wrong. It does read now. It used to say empty. Dealer replaced fuel gauge, now it reads but it is not accurate. I don't mean not perfectly calibrated. It is not reading correct. It originally always read full way too quickly (probably 3/4 tank or sooner) but it did track down to empty correctly. Now it can say 3/4 tank and be empty. I suspect the sending unit. It is a 3 pin sensor. I disconnected the lead coming to the sensor to measure the incoming signal. I did measure 12 volts supply in the plug. I got 7 volts from the middle pin to ground. I am assuming that is correct. If someone can tell me that probably indicates the sending unit, I 'll just buy one. If not any trouble shooting ideas are welcomed. I went to the automotive store to buy a connector where I could put the sensor in a glass of fuel and test output but they did not have a matching plug.

One other note, I had a polarity issue (hooked battery up backwards while changing in the dark, I bought a battery and the caps were on the wrong terminals.) This was the cause of the fuel gauge being replaced along with a couple of others at the same time. Possibly there is something else that could have fried when that was done. But everything else electric works now including all other gauges, the speed control, blowers, pumps, dashlights, etc.

woodrowskis 05-29-2013 02:24 AM

I did find a test method but I do need the correct electrical connector and apparently need some resistors to confirm the gauge . Anyone know if it is the same resistors for the 3 pin? I may can figure this out from the middle pin voltage. I will think more on this at a better time of day.

mikeg205 05-29-2013 07:09 AM

is it the right length?

woodrowskis 05-29-2013 09:39 AM

it may not be perfect, that could cause the full too soon issue, but it always worked accurately from 3/4 down to empty before. thats all I really care about.

MI_Corey 06-02-2013 08:30 PM

I'm having the same problem but mine only goes to about 1/8 of a tank and stays there.

woodrowskis 06-03-2013 08:26 AM

Testing the sending unit versus the gauge was going to be a pain. I ordered a sending unit. It fixed the problem. I have not filled it or driven to empty to check accuracy. But looking at the amount of gas in the tank, it seemd to read right. Andd after adding 5 gallons, it seemd to go up the appropriate amount.
Therefore, short of a computer to check codes, my guess is that if you measure 12 v on supply and 7v middle pin when unplugging the connection to the sending unit. The problem is probably the sending unit.

HRC 06-04-2013 12:21 PM

Where did you order your new sending unit, I need one my self and I'm finding lots of 2 wire but having trouble finding what I think is the right 3 wire. My boat is an '01 Prostar btw.

chriscraftmatt1976 06-04-2013 12:35 PM

Man, mine's po-zessed as well this season. sometimes when i turn the key on it works fine, sometimes it registers incorrectly, sometimes doesn't work at all, and each time i turn it on a different result. put in a new sending unit last fall and it worked fine then. checked the wiring 4 times so far. at this point i just keep filling it up. problem solved!

g-Dog 06-04-2013 01:00 PM

I adjsuted mine last year using the calibration instructions...and it's worked great ever since.

mikeg205 06-04-2013 01:02 PM

you can test the resistance to check accuracy...

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