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Rob 129
06-23-2008, 05:53 PM
fuel gauge reads a 1/2 tank allways. replace gauge or ?:confused:

Footin
06-23-2008, 08:41 PM
Sending unit.

JimN
06-23-2008, 09:30 PM
Almost always the sender.

Ski-me
06-23-2008, 09:48 PM
Just a thought before replacing......

I found a few adjustment screws on top of the sending unit and after playing around with them a bit, mine is working pretty good. I did buy a sending unit but have not installed it yet because my guage seems to register pretty good now. Also, this is free!

I found these adjuster screws after I bought the sending unit and the dealer would not take back any electrical item after purchase. So it's just sitting on my shelf for now......$75.:rolleyes:

erkoehler
06-23-2008, 10:07 PM
Sending unit.

Like you would know:D

robin
06-23-2008, 10:21 PM
if your sender is like mine, it has several magnets on the float inside inside it. one of mine came out and it always read 1/4 tank. i just glued the magnet back in place and it works great

Skipper
06-26-2008, 11:41 AM
Some sending units can be adjusted. Best method is to fill the fuel cell completely. The guage should read full. If not, then slowly turn the screw until the sender reads full.

yankee
06-27-2008, 01:40 AM
Rob,

There's a couple different type of sending units used over the years, not sure what yours is. If you remove the hot wire from the sending unit the gauge should go to empty, if you touch it to the ground the gauge should go to full. If it does both it's the sending unit, if doesn't it's the gauge.

The new centroid sending units they're selling seem to work really well.

gguppy
07-14-2008, 07:41 PM
I read some where you could clean the unit . Mine was working until i fill it up. The gauge reads 3/4 but it is empty. 92 Prostar 205

JimN
07-14-2008, 08:51 PM
It's less a matter of cleaning it and more of making it able to move freely. The slots on the float need to be made a bit wider.

gguppy
07-14-2008, 10:10 PM
Have you done this before is it easy ,could you tell some sort of intruction because the unit are back order and i could save 75.00 dollars.

Muttley
07-15-2008, 11:50 AM
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.

http://i112.photobucket.com/albums/n170/MuttleyC90/StuckFloat.jpg


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.


http://i112.photobucket.com/albums/n170/MuttleyC90/Sandedfloat.jpg

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.

flipper
07-15-2008, 12:03 PM
Good write up muttley!!!! That's what I had to do on my '91 a couple years ago. No problems since then.

mayo93prostar
07-15-2008, 01:02 PM
Mutt, great description and pics. I did similar process on my 93 last year. However, it is sticking a little again this year and I think it was because I did not sand the grooves, only the outside. I will have to take it apart again and do grooves and outside a little more. I used superglue to glue magnets in and to put bottom cap on. I let it sit in gas overnight to see if glue would hold and it did. I guess I will also have to check if the magnets came unglued. Also, what site are you referring to?

JimN
07-15-2008, 02:14 PM
I haven't seen the outside diameter cause a problem, only the grooves. I suppose it can be, but as long as it slides freely, it should work.

Muttley
07-15-2008, 02:51 PM
what site are you referring to?

www.muttley.ca. It's in the process of being reworked, so it's still my old site. I have since shut down my company since taking over another one.

I'm putting together a more personal site which will be up and running eventually. I hope to have a nice tips & tricks section.

Muttley
07-15-2008, 02:55 PM
I haven't seen the outside diameter cause a problem, only the grooves. I suppose it can be, but as long as it slides freely, it should work.

That's the key.

On mine, the plastic sliders inside the tube had a slight warp. Opening up the side grooves in the float a little compensated for that. The float had flaired at the ridges so sanding the edges took care of that.

nwhittuk10
07-25-2008, 03:11 PM
Hey Muttley where exactly could I find the gas tank at? My gas guage is currently reading full all the time (Possibly just wishful thinking on the boat's part). Just bought the boat recently and do not have much experience in this type of field. I do have people that could help as long as I can explain the problem to them and your illustration on how to fix it, just need to find the gas tank to slide it some or w/e you had talked about. Thanks.

bigpack20
07-25-2008, 03:20 PM
My fuel gauge will go to full but when I run the baot it will not go below 1/2 tank. would that be a sending unit. Were would the sending unit be on a 1998 pro star 205???

Thanks for the help!

JimN
07-25-2008, 04:13 PM
It's behind the rear seat.

Muttley
07-25-2008, 04:54 PM
Hey Muttley where exactly could I find the gas tank at?

On my '92, you lift the rear seat out, then pull out the reamining rear panel from the bottom. The sending unit will be on the top of the tank toward the port side.

My fuel gauge will go to full but when I run the baot it will not go below 1/2 tank. would that be a sending unit. Were would the sending unit be on a 1998 pro star 205???

Thanks for the help!

I'd still say it's the same thing. On mine, the slider ridges inside the tube were slightly warped. That's why I had to sand out the grooves in the float. Your's may be warped at the 1/2 way point not allowing the float to go all the way to the bottom. I believe the '98 tank is similar, but you may need to remove the vent and filler hoses.

bigpack20
07-25-2008, 08:50 PM
Thanks for all the info

gguppy
07-26-2008, 10:49 AM
thanks for the advice (Muttley) this work perfectly. This wed site is the best!!!!!!!! Note at the top of the sender i saw that it is begin to crack, i guest that i will have to replace soon, but for now its is working. Thank for now.

WishIWasSkiing
08-14-2008, 10:05 AM
I've got a 96 PS205 that's new to me, & the fuel gauge was stuck at 7/8 full. I figured it'd be the stuck float in the sending unit, but it slides freely. Then I thought it might be a bad ground - nope. When the key is turned to off, the gauge goes down to E like it should, & pops up to 7/8 when key is on. Could it be a bad gauge? Anyone else have any non-stuck-float-in-the-sending-unit problems/solutions?

JimN
08-14-2008, 10:23 AM
Did the float have two small magnets on it? If not, they're probably on the circuit board, close to the top. The gel type super glue works pretty well.

WishIWasSkiing
08-14-2008, 02:10 PM
Yes, the magnets were in place. I even bought the gasoline resistant glue figuring they'd be dislodged or they'd get dislodged in the sanding process.

coz
08-14-2008, 02:18 PM
Here's what I did http://www.mastercraft.com/teamtalk/showthread.php?t=21325

JimN
08-14-2008, 04:16 PM
Turn the key to ON and watch the gauge, then disconnect the pink wire. If it stays there, disconnect it from the gauge and see if that makes any difference. If the pink is off of the gauge and it still goes to 7/8, it's a bad gauge. If you connect the two wires on the sender, the gauge should go to FULL.

jomiddour
04-26-2010, 02:45 PM
Would I need to remove the gas tank to access the sender or can it be removed from the top of the tank while its still in place?

Thanks!

Chicago190
04-26-2010, 04:18 PM
Would I need to remove the gas tank to access the sender or can it be removed from the top of the tank while its still in place?

Thanks!

What year and model?

rjklein
06-27-2010, 08:41 AM
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.

http://i112.photobucket.com/albums/n170/MuttleyC90/StuckFloat.jpg


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.


http://i112.photobucket.com/albums/n170/MuttleyC90/Sandedfloat.jpg

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!

Surfer
05-07-2012, 11:42 AM
Hi,

any idea what material the float is.
Or if possible to get the float with magnets from somewhere?

GKinTN
05-15-2014, 06:52 PM
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.

Thanks!