07-26-2008, 07:16 PM #1
input please. '96 slt 780 limp mode...
Start off by saying hi to everyone im new to the PWC community. Just a week ago i purchased a '97 kawasaki STS 750 which has proved itself to me. Along with that I got a '96 SLT 780 which is to be honest making my head hurt.
Point of the post is the SLT is in its Low fuel limp mode, the MFD hasn't worked, it sounds like something in the MFD is broke. I pulled it out and notcied that it makes a rattling sound like a bad light buld. Then traced down to discover the red/purple wire had been cut. I reconnected that nothing, check fuses nothing. Thats when I discoverd the issue of the safe mode. Idles great, revs up great new plugs, compression, gas all good. Full throttle, sounds like a drag car ready to launch at the track. in the water its just sunday driving. I've been all over the web trying to find an answer on hot to bypass the LR54. I've read it's just cutting the grey wire, it's cutting out the fuel sender and splicing a 100ohm resister, just cutting a connecting no resister. I've tried everything and would greatly appreciate if someone could tell me exactly how to do the bypass. If any one could help that would be awesome.
07-26-2008, 09:01 PM #2
- Join Date
- Jul 2007
- near Toronto, Canada
Both the oil and gas fuel senders are marine standard resistances;
33 ohms from the Blue (oil) or Pink (gas) wire to ground means full, 240 ohms to ground means empty.
Connect a 33 ohm resistor between the Pink (for fuel) wire and the black wire, and disconnect the actual sender. That should stop the low fuel signal. Most guys do the resistor install inside the wiring box, rather than at the tank.
If you can, get the MFD working. It really does help you keep tabs on the engine, and a low oil warning is better than a seized engine. A low fuel warning is better than getting stranded.
Have you checked the ground for the MFD?
If it has 12 volt power and ground, the MFD should show a display. Pin connections are listed in the electrical diagrams, in the 1992-1998 Service Manual.
07-26-2008, 10:37 PM #3
i've printed and studdied all the diagrams I could find and drawing a blank on the MFD. I agree 100% on the importance of it but avalibility is the issue and im trying to keep this ski cheep until i round up some newer skis. It would be great if anyone out there had a working MFD or new of a cheap one to purchase and plug in to help with the troubleshooting.
I'm kind of in a tight spot with this SLT seeing as the closest service shop to work on it is over an hour south of me. I'm located in north StL 10 minutes from alton. If someone around me knows of a closer service center please let me know. Also I'm struggling with finding a place that carries oil for it. everything I've been reading says polaris two-cycle oil??? I've got a YZ 250 2-stroke, but with this im lost.
Thanks for the help.
07-26-2008, 10:58 PM #4
- Join Date
- Jul 2007
- near Toronto, Canada
Yamaha, etc all use similar TC-W3 oil, as do the better outboard oil brands. Synthetic TC-W3 is better, if you can.
Note that Sea-Doo uses a different spec oil, not TC-W3.
You can get Amsoil 2-stroke oil delivered to your door. There is an Amsoil guy on GreenHulk (800Amsoil4U).
I recently bought a case of Amsoil HP Injector for my Polaris PWC, which is also recommended by a number of other Green Hulkers.
Take the MFD out of the PWC, and connect 12 volts to the power and ground pins. Pin 1 is 12 volts, pin 2 is ground. See if it wakes up. Don't short anything, and don't get the polarity backwards.
If it works on the bench, then you just need to trace the black and Red/Purple wiring back from the MFD, through the electrical box connections, to the battery.
A bad ground is my guess, or corrosion on the board inside the electrical box (check that board, front and back, for ANY signs of rust).
07-26-2008, 11:10 PM #5
07-26-2008, 11:26 PM #6
And thats a negative on the MFD coming to life on a direct 12v supply. Good idea worth a shot but I'll keep hunting.
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