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View Full Version : going on 3rd fuel sender in 4 months


vrsc
04-26-2012, 11:28 PM
Purchased 1999 Sportstar and the sender wasn't working. Decided to purchase one from mastercraft (2 wire) to replace the stock on the everyone has had problems with. The install went fine and gauge worked fine. Took boat out and fuel gauge started started acting crazy and not working at the end of the day (running boat about 2 hours). Replaced it with another one from MC and this one has worked fine for the last 4 months (40 hours of use) and today the gauge was working and by the end of the day it sits at empty. At key up, it swipes amd goes to full and then creaps down to empty. I am sure Mc will replace the sender again for (hoping here) by what is going one. Wiring was basic and I heat shrink wrapped all open connections.
any thoughts and help would be great

mikeg205
04-26-2012, 11:52 PM
I would trace the wires all the way from the gauge to the sender look for corrosion. Check the resistance/voltage being sent from the sender...Pull it up and down and see if the readings change....possible bad gauge?

vrsc
04-27-2012, 06:07 AM
Yeah. I'll trace the wires but after the past 2 stopped working, I replaced and the new ones worked right away. Even hooking the old ones back up to see if I was crazy but the old didn't work.

mikeg205
04-27-2012, 09:03 AM
use a voltmeter on the old ones hook up the wires and see if any voltage is coming thru...there's only a variable resistor on the sending unit...maybe there's was bad run of resistors? When you said checked old senders...did you use a voltmeter or your gas gauge.

coz
04-27-2012, 09:38 AM
Yeah. I'll trace the wires but after the past 2 stopped working, I replaced and the new ones worked right away. Even hooking the old ones back up to see if I was crazy but the old didn't work.

I know it's a little late but for others, they can go here for senders to fit the older models, they're the ones that supplied MC's with sender units in the past. I don't know if they still do but when I needed one a few years ago they hooked me up and I haven't had a prob since.

>>>> http://www.isspro.com/

JimN
04-27-2012, 09:46 AM
Purchased 1999 Sportstar and the sender wasn't working. Decided to purchase one from mastercraft (2 wire) to replace the stock on the everyone has had problems with. The install went fine and gauge worked fine. Took boat out and fuel gauge started started acting crazy and not working at the end of the day (running boat about 2 hours). Replaced it with another one from MC and this one has worked fine for the last 4 months (40 hours of use) and today the gauge was working and by the end of the day it sits at empty. At key up, it swipes amd goes to full and then creaps down to empty. I am sure Mc will replace the sender again for (hoping here) by what is going one. Wiring was basic and I heat shrink wrapped all open connections.
any thoughts and help would be great

Take a fuel sample and look for water, debris, etc. These are very accurate, as long as the fuel isn't contaminated. Gas has its own characteristics and water, ethanol or ethanol/water has its own. This means that as soon as something that may be in the tank but not in the areas of the sender gets to the sender, accuracy goes out the window.

How did you connect the wires and make the change from the two-wire sender to the three-wire sender?

vrsc
04-28-2012, 11:25 AM
Take a fuel sample and look for water, debris, etc. These are very accurate, as long as the fuel isn't contaminated. Gas has its own characteristics and water, ethanol or ethanol/water has its own. This means that as soon as something that may be in the tank but not in the areas of the sender gets to the sender, accuracy goes out the window.

How did you connect the wires and make the change from the two-wire sender to the three-wire sender?

Originally my boat came with an isspro sender and had positive and negative terminal connectors from the sender to a 2 wire wiring harness. This harness on thesender side had a green static ground that went to the fuel fill up. The new mastercraft 2 wire sender all come with the red and black wires backwards at the harness so I just needed to just cut, splice and heat shrink wrap the but splice connectors and then plug and play. I could never get the past senders to work again but replacing them with the new senders worked instantly after hook up.
I will check my gas tank for contaminents (just as I have in the past) but when the gas gauge has stopped working, it has always been instant with 3/4-1/2 tak full of gas as I have never ran anything lower than 1/4.
My MC dealer has some of these senders on order and did seem to think that it was the part that was falling. It's just a big pain in the but for me to keep changing these out. The only reason I chose not to get the isspro part was because every boat that intially came with these failed and needed to be replaced and I thought that getting a different part that MC sold would be a positive fix

vrsc
04-28-2012, 11:28 AM
also, in the past wwhen these MC senders failed on me, the gauge instantly went to "E" with some bouncing but the when the isspro sender failed, the guage was stuck at 3/4 Full with no bouncing when there was movement

JimN
04-28-2012, 03:04 PM
Originally my boat came with an isspro sender and had positive and negative terminal connectors from the sender to a 2 wire wiring harness. This harness on thesender side had a green static ground that went to the fuel fill up. The new mastercraft 2 wire sender all come with the red and black wires backwards at the harness so I just needed to just cut, splice and heat shrink wrap the but splice connectors and then plug and play. I could never get the past senders to work again but replacing them with the new senders worked instantly after hook up.
I will check my gas tank for contaminents (just as I have in the past) but when the gas gauge has stopped working, it has always been instant with 3/4-1/2 tak full of gas as I have never ran anything lower than 1/4.
My MC dealer has some of these senders on order and did seem to think that it was the part that was falling. It's just a big pain in the but for me to keep changing these out. The only reason I chose not to get the isspro part was because every boat that intially came with these failed and needed to be replaced and I thought that getting a different part that MC sold would be a positive fix

OK, if you have the 2-wire harness, it's a later '99 boat- the first ones had a 3-wire harness and when the first later '99 boats were made, they needed an adapter to go from 2-wire to 3-wire.

How did you adjust the senders when you replaced them? They all need to be calibrated. Do these have two small potentiometers on top? You need to calibrate Empty first, then Full, checking Empty when you're done. I usually set Empty with a few inches of gas in the tank, so it didn't strand anyone. If you want to avoid inaccuracy, cut the tube shorter than the bottom of the reservoir and set Empty at the bottom of the tube. Thay way, if you have water in the gas, it won't be inaccurate because of the added substance.

vrsc
04-28-2012, 04:21 PM
I did purchase that 2 wire (trailer type adapter) at the very first sender replacement so that i would have to keep xurring ans tapping in the OEM wiring. These MC senders do not need to be calibrated (clearly state "auto calibration" on them and don't have calibration screws).
I cut the first on but the newest one I decided not to since it was only 1/8th of an inch and it gave me more of a reserve type reading. Right now, I have 3/4's Full tank and it's reading "E" so I feel something is wrong instead of it reading inaccurate. Before replacing this sender again, is there anything that might be causing these sender failures or Just a bad batch of senders?

JimN
04-28-2012, 04:47 PM
I did purchase that 2 wire (trailer type adapter) at the very first sender replacement so that i would have to keep xurring ans tapping in the OEM wiring. These MC senders do not need to be calibrated (clearly state "auto calibration" on them and don't have calibration screws).
I cut the first on but the newest one I decided not to since it was only 1/8th of an inch and it gave me more of a reserve type reading. Right now, I have 3/4's Full tank and it's reading "E" so I feel something is wrong instead of it reading inaccurate. Before replacing this sender again, is there anything that might be causing these sender failures or Just a bad batch of senders?

This type of sender is very widely used, so I doubt it's a bad batch. As I posted before, they are very accurate, but only if the liquid they're measuring is clean. If you have water, ethanol and other substances in the tank, whether intentionally or accidentally, I would suggest testing it in clean gas. I used a clear plastic bottle for this and it would verify your sender's status- pass or fail. Are you using the same part? The OEM senders from MC used to have the part number on it, possibly starting with 81 (MC's part designation). I would check with MC to find out if they use adjustable senders (they did when I worked at the boat dealers)- if they aren't adjustable, I don't see how they'll auto-correct if the makeup of the fuel changes.

mikeg205
04-28-2012, 06:47 PM
The only other possibility is a bad gauge...the send is only a variable resistor 30-240ohms usually. It is strange that its failing over and over.....unless the voltage regulator is some how providing over current situation and frying the resistor out. Check the broken one and see if there's any continuity.... then check the voltage coming in...another thing could be a bad ground forcing more current thru the sending unit. just ... an additional .02.

here's what happens...http://www.youtube.com/watch?v=fVf9JdTs5Ew

vrsc
04-28-2012, 10:18 PM
I'll check everything that has been mentioned. Thank you

vrsc
04-28-2012, 10:21 PM
as for the bad gauge comment, each time I've replaced the senders I've done the shorting out technique and the gauge always goes past the "F". Is there another way to tell if the gauge is bad?

mikeg205
04-28-2012, 10:27 PM
good luck - I hate those nagging issues...

JimN
04-28-2012, 10:32 PM
The only other possibility is a bad gauge...the send is only a variable resistor 30-240ohms usually. It is strange that its failing over and over.....unless the voltage regulator is some how providing over current situation and frying the resistor out. Check the broken one and see if there's any continuity.... then check the voltage coming in...another thing could be a bad ground forcing more current thru the sending unit. just ... an additional .02.

here's what happens...http://www.youtube.com/watch?v=fVf9JdTs5Ew

They stopped using senders with moving parts after '98. These use capacitance, IIRC. They're not just a moving arm or float with magnets.

The current to the sender isn't significant- think about what would happen if the sender had an internal short while it's inside the gas tank.

mikeg205
04-28-2012, 10:33 PM
They stopped using senders with moving parts after '98. These use capacitance, IIRC. They're not just a moving arm or float with magnets.

The current to the sender isn't significant- think about what would happen if the sender had an internal short while it's inside the gas tank.

exactly!

JimN
04-28-2012, 10:41 PM
as for the bad gauge comment, each time I've replaced the senders I've done the shorting out technique and the gauge always goes past the "F". Is there another way to tell if the gauge is bad?

I posted earlier that you can check in fresh gas, in another container.

vrsc
04-28-2012, 10:53 PM
I posted earlier that you can check in fresh gas, in another container.
in the past installs I've done this to check accuracy before installing the new sender. When putting the sender into the tank afterwards I was able to tell where the 1/2 or 3/4's fuel mark was and all new senders read accurately and gauge worked fine without a hitch

-V-
04-30-2012, 09:46 AM
to test my sender i used a kids container. you can buy those long tubes for bubbles for the kids. after they use all of the bubble solution, take it and put it in your inventory. the tube is exactly the size for my fuel sender. it's about 1" in diameter and 14"-16" long. Put the sender in there, then add fresh gas from a gas can. Mine still is a bit eratic but at least i know when i get to a half tank. I have to adjust it more later. it is VERY time consuming.

vrsc
05-04-2012, 07:08 PM
well, MC gave me a new sender to try out so I'll see what I can do to get the old one working again before replacing

vrsc
05-04-2012, 07:13 PM
Originally my boat came with an isspro sender and had positive and negative terminal connectors from the sender to a 2 wire wiring harness. This harness on the sender side had a green static ground that went to the fuel fill up. The new mastercraft 2 wire sender all come with the red and black wires backwards at the harness so I just needed to just cut, splice and heat shrink wrap the but splice connectors and then plug and play. Do you think that cutting the green fuel fill up ground could be causing the problems? I know other owners did the same things since the new MC part harness doesn't have the green fuel fill up ground wired into it.

vrsc
05-07-2012, 08:29 PM
Well new sender from mastercraft is in and it reads perfectly. The old one is dead. Doesn't work in the tank nor fresh gas in a 2 liter. Just read empty. I went ahead and sliced the green static ground back into the connection. not sure if that was causing an issue or not

JimN
05-07-2012, 08:36 PM
Well new sender from mastercraft is in and it reads perfectly. The old one is dead. Doesn't work in the tank nor fresh gas in a 2 liter. Just read empty. I went ahead and sliced the green static ground back into the connection. not sure if that was causing an issue or not

Your new one is grounded, right? Better be.

mtajpa
05-07-2012, 10:04 PM
Well new sender from mastercraft is in and it reads perfectly. The old one is dead. Doesn't work in the tank nor fresh gas in a 2 liter. Just read empty. I went ahead and sliced the green static ground back into the connection. not sure if that was causing an issue or not

Might want to read thru this thread. I was told there was a recall about the removal of the static wire that actually goes from the filler neck to the fuel pump housing.

http://www.mastercraft.com/teamtalk/showthread.php?t=10679&highlight=fire+hazard+ground

JimN can probably confirm this.

vrsc
05-08-2012, 06:12 AM
Might want to read thru this thread. I was told there was a recall about the removal of the static wire that actually goes from the filler neck to the fuel pump housing.

http://www.mastercraft.com/teamtalk/showthread.php?t=10679&highlight=fire+hazard+ground

JimN can probably confirm this.
Yes, I read through that and that was one reason why I clipped it off of the harness but 2 senders later and lots of scratching my head to diagnose what might be causing the senders to Go bad other than just the parts not being bad. So I put green static ground back into the mix just to see if it would help my sender last more than 4 months

JimN
05-08-2012, 09:59 AM
Yes, I read through that and that was one reason why I clipped it off of the harness but 2 senders later and lots of scratching my head to diagnose what might be causing the senders to Go bad other than just the parts not being bad. So I put green static ground back into the mix just to see if it would help my sender last more than 4 months

The green ground wire is for eliminating buildup that could cause a spark when someone or something contacts it or for dissipating static buildup in the sender. The plate may not even be connected to the sender itself, other than being mounted to it but this is for safety- wearing pants while working on a boat is great when the air temperature is low but scooting around on the carpet while wearing pants builds up a lot of static and if gas fumes are present while it's discharged, "Boom" goes the dynamite.

vrsc
07-29-2012, 11:23 PM
well, it happened again. Was out on the lake today and gauge went from above 1/2 tank to below Empty. Finished up on the lake and got gas and filled the tank to the neck. Now gauge reads 3/4. What is going on, This is nuts.