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Old 06-27-2010, 07:41 AM
rjklein rjklein is offline
TT Newbie
Join Date: Oct 2009
Boat: Pro Star 190 1990 454
Location: Midwest
Posts: 6
Originally Posted by Muttley View Post
Here's an article I was working on for my site, but it's not quite finished yet:

If you own an older Mastercraft Prostar, you may have had an issue with the fuel gauge not working or getting stuck. Before you run out and spend a boat load of money getting it fixed or replaced, you may consider fixing it yourself. My gauge hadnít worked since I got the boat so I decided to check it out. I found the fix to be actually quite simple.

First I had to slide the gas tank forward. This wasnít as hard as I thought. There are four clips, two at the front bottom into the floor and two at the top back. The tank will slide forward enough to get the sending unit out. I undid the two wires after marking the positive, removed the five screws holding it in place and pulled the unit.

Inside the sending unit, there are two magnets attached to a float. The float had swelled over time and the magnets had come out of their groove and got stuck between the float and the circuit board.

The bottom cap of my sending unit just fell off. Iím sure itís supposed to be glued on, so you may have to carefully cut yours off.

My next step was to free the float. I stuck a length of bailing wire with about a ľĒ hook on the end and pulled the float out. I lightly sanded the edges and inside the guide grooves until the float slid freely up and down the tube. Donít get too aggressive as the float material is pretty light and sands easily. It doesnít take much.

Next was to glue the magnets to the float. I used G2, but Iím sure you could use any epoxy that doesnít break down in gasoline. Since the whole unit is immersed in gas, thatís kind of important.

Then I inserted the float into the tube. I put my magnets toward the bottom of the tube so that the gauge would read empty sooner than later. Just a little precautionary thing. Then I glued the end cap back on. Be sure to slide the float up a bit so you donít accidentally glue the float to the end cap. I resisted the urge to put it back together and let it sit over night.

I dropped the sending unit back into the tank and tested the unit by turning the key on and moving the unit up and down. It seemed to work, so I inserted the 5 screws holding it down, connected the wires and and shoved the tank back into place. Then I had a beer to celebrate while vacuuming the boat.

Saving money is good.
This is a excellent post, thank you for taking the time and providing pictures. I have a 1991 prostar and the gauge is stuck. I am going get her fixed with this post!
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Old 05-07-2012, 10:42 AM
Surfer Surfer is offline
TT Regular
Join Date: Sep 2004
Boat: MC PS 190 1995, 350 cid. injection, 275 hp, 1:1, 4-blade prop.
Location: South Finland
Posts: 48

any idea what material the float is.
Or if possible to get the float with magnets from somewhere?
PS190 1995 5.7 l EFI TBI 1:1 13x13 4-blade prop. Barefoot boom, wakeboard boom & fatsack. UK made trailer
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Old 05-15-2014, 05:52 PM
GKinTN GKinTN is offline
TT Regular
Join Date: Oct 2013
Boat: 1991 Prostar 190
Location: Southeast - Nashville, TN area
Posts: 91
I thought I'd bump this thread and say "thanks!" as it helped me fix the gas gauge on my '91 PS190. My gauge was stuck on full. I'll give a little detail that might help with this exact era setup.

I made sure the battery was NOT hooked up then I siphoned as much gas out of the tank as possible before I dug into it. On this era hull the gas tank only needs to be slid out on one side just a little for the sending unit to clear for removal. I just removed the lower tank brackets, and held the top ones up a hair and slid the tank just a few inches forward on one side. Once you have the sending unit out you remove the nuts holding the two wires, then also remove the round brass slotted fittings under each terminal. You don't have to remove the top plastic assembly from the main aluminum tube that can stay together. After removing the plastic cap off the bottom of the sending unit (mine had 2 screws) you can then slide the circuit board assembly out the bottom end. My magnets had both fallen out of the float and were stuck in random places. I smoothed out the float with a little sand paper, than I decided to use JB weld to reglue the magnets in place (at both ends of the float slot) with them oriented opposing each other magnetically. I noticed one of the main terminals up top had a cracked solder joint (it is also riveted) but I resoldered that being careful to keep the two terminals aligned straight. I then sealed the tank up temporarily and let the JB weld cure for a day. Put it all back together and the gas gauge now works great and it cost me next to nothing.


Last edited by GKinTN; 05-15-2014 at 06:02 PM.
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