95 Polaris SLT 750 pulsing on hi rpm

[Jeff Walkowiak]

go to www.sbtontheweb.com order the kits and rebuild the carbs diaphragms definitely do not last forever, and they also get stuck to the covers a lot, you have fuel starvation and you have done everything else possible.

 

[Jeff Walkowiak]

Re: 95 Polaris SLT 750 pulsing on hi rpm

i hesitate to tell you this for obvious reasons but when i suspect fuel starvation on a ski i run with the seat off, and the air box open when it acts up i give the carbs a shot of start fluid, if it picks up and runs good for a few seconds i know it is starving for fuel, however if it is some other issue the engine will fall flat and you better be holding on or you will fly over the bars and get run over by the ski, i did have a ski that drove me crazy trying to find the problem and it eventually turned out to be bad core wire in the plug wires but i do not believe this is your issue

 

[Jeff Walkowiak]

Re: 95 Polaris SLT 750 pulsing on hi rpm

that i can't honestly tell you , i also use the little plug wire lights and put on on each plug to visually see the ignition fire, when the engine acts up it will show you if the ignition is cutting out, but i still feel it is fuel in your case

 

[Jeff Walkowiak]

Re: 95 Polaris SLT 750 pulsing on hi rpm

I just wanted to warn you , I almoast flew off a gtx running around 45 mph once . so it could really ruin your day. it is a little trickey when you are riding standing up holding the throttle with one hand and leaning down and sideways to see where you are spraying that starting fluid, hoping it doesn't backfire in your face and if it isn't fuel starvation it will absoloutely stall out the engine.

 

[Jeff Walkowiak]

Re: 95 Polaris SLT 750 pulsing on hi rpm

check on buying just the diaphragms not at sbt but at the dealer, use the carb number if they are mikouni carbs lots of them use the same one I buy yamaha parts because they are the same for sea doo but sea doo charges twice as much

 

[Fasman]

Re: 95 Polaris SLT 750 pulsing on hi rpm

Jeff try this one on for size WEIRD!!!!
WEnt to the dealer for the diaphrams and they didnt have but I got a kit coming WPS for 16 bucks per carb.....
Now on the way to the lake I had taken carb rack off and went completely thru it the diaprams are stretched compared to new.... ANYWAY I recall seeing on here or sbt that plugs are improtant I had put on NGK BR9 ES ( thats what my sleds run.,...ayway I stopped and bought brp7es plugs...got to lake installed them and took off for a test run..... went about 1/2 mile and sputter WHAM 6100 RPM and holy crap it was BACK!!!!!!!!!!!
Fast forward today back to same old thing 4100-5000

Two thoughts now... the diaphrams are still bad and streched after being in gas gfor a day and just did so when I put the back in after drying out... OR I am oil rich and am fouling plugs... they look good on electrode but black around them....and it uses a bit more oil than I think it should..... and there is a bit of smoke at exhaust..

THis is v[ery strange troublehsoot isnt it

 

[Jeff Walkowiak]

Re: 95 Polaris SLT 750 pulsing on hi rpm

there is a notch on the oil pump to set it correctly see where it is with the pump adjustment or your pump is going bad and leaking oil . a 9 is a hotter plug than a 7 polaris is known for running too lean , and people have different fuel pumps for that issue, just for grins crimp the return fuel hose that goes back to the tank after it feeds all those carbs I use a cable tie and make a loop in the hose , then with the hose pinched I use the tie to hold it so it is pinched off if the ski runs better at top speed with the return line clamped closed that confirms that you have a fuel delivery issue and you will need to address the fuel pump issue I always use an electric pump and a relay switch but I don't have the time to get in to that right now.

 

[Fasman]

Re: 95 Polaris SLT 750 pulsing on hi rpm

Ok I will do that as well as put those rebuild kits in...... You do recall that I pulled the stock fuel pump and put a 3 outlet pump on from one of my sleds right????? I am getting closer and it was nice to have it run right for a bit

 

[Jeff Walkowiak]

Re: 95 Polaris SLT 750 pulsing on hi rpm

I didn't recall the pump mod, but that is a good thing to do since those had the issue with melting the pistons from running lean, but even that pump works on a pulse from the case, an electric 3-4 lb fuel pump does a lot of things, 1 it primes the fuel system before you start the ski making cold starts easy, it keeps a steady supply of fuel to the carbs at all rpm's and with a good filter installed in the line it keeps the fuel system clean as it circulates the fuel through the system. and it can be used with the existing pump so if something happened to it the original pump keeps the engine going.

 

[Fasman]

Re: 95 Polaris SLT 750 pulsing on hi rpm

well Jeff the pain continues....new diaprhams and still the same pulsing.....Now I tried some carb adjustments (very minor)checking plugs alot this weekend and 1 snd would be fine 2 rish then next check 12 fine 3 rich......Gonna think about the oil injection as the cause at this poin....those oil pumps when going go full rich soooooo I am just gonna block it off and go premix.

any suggestions now???

 

[Jeff Walkowiak]

Re: 95 Polaris SLT 750 pulsing on hi rpm

now we know the carbs are ok it is time to get in the ignition first check each plug wire lead, remove the plug cap end and use a pair of needle nose pliers to pull om the inner wire if it pulls out the wires are bad, you also need to clean all electrical wires connection blocks for the ignition. I had a similar issue with a kawasaki and it was bad plug wires, I naturally blamed the carbs first. and found the wires by accident.

 

[Fasman]

Re: 95 Polaris SLT 750 pulsing on hi rpm

OK I will do that....BUT HOW do you explain the diff plug colors when I wasnt changing anything.... I would ride and check the plugs 1 hole was rich next plug check NO CHANGES it was spot on then next check rich then next check lean......would spark do that???
Thanks for hanging with me on this one..... it will be one for the book of WEIRDazzzzzz when we ( U n ME ) get it figured out

 

[Jeff Walkowiak]

Re: 95 Polaris SLT 750 pulsing on hi rpm

bad spark or weak spark will definitely cause the problem and a water box full of sand will do that also,, have you looked in the water box to see if it is clogged up with garbage 2 strokes are really funny about proper exhaust back pressure.

 

[Jeff Walkowiak]

Re: 95 Polaris SLT 750 pulsing on hi rpm

one thing bothers me about your original post is that you used an old fuel pump from another ski, try an electric fuel pump, wire a 20 amp or better relay from your battery to a circuit that comes on when the engine is on use a 12 volt purolator pump rated at around 3 psi, have it feed the carbs this is not expensive cost less than 50 bucks to get the pump and relay, I mount them on a strip of stainless or aluminum and bolt it under the helm on one of the bolts that hold the helm assembly to the hull, . also use a clear vinyl tube for your return line and that allows you to see the fuel going back to the tank and if you have air bubbles in that you know it is sucking in air someplace and air will cause the same result you are experiencing.