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  1. #1

    Help my 97 xp will start and run on trailer but it's hard to start in water

    I can get it to start when it's not under a load. But when in water it hard to start. I checked compression they are both 140. Just had carbs and fuel pump rebuilt. Still doing it. Any suggestions? This is my first ski I'm new to this


  2. #2
    Waterluvr's Avatar
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    You'll get differences of opinion on 787's with 140 psi, in my world it's time to show that engine some work and get it back in spec before performance drops off any farther. Depending on where you're at related to sea level that engine has lost 10-15 pounds of compression already and that's all the heads up you need to evaluate it for a new top end at the very least.

    You read all the horror stories about engine meltdowns for a reason, most people ignore that 10-15 pound loss and keep on running them because most still run pretty good at those numbers but why isn't your's?

    Could be several reasons, take another compression test using a different gauge unless you're using a professional grade calibrated instrument just to be sure it's not lower than 140, 125 psi engines aren't going to start and idle in the water with much more than a box lunch parked on the seat if at all.

    How big are you? I have some corn fed beef eating Midwest boys for customers that wouldn't hop their 300 pounds on a 787 powered ski and get it to start and idle for long with a 140 psi motor ever no matter how perfect everything was in tune.

    That aside can you turn the pto by hand with the plugs removed without much resistance? Bad pump bearings, thrust washer etc. puts a harder load on the shaft and motor than what should be there and makes starting/idling hard. Turn the pto over several complete revolutions by hand and see if everything feels consistent through the turn. Any noise, hang ups etc. you have issues that are compounded when the pump is under a load.

    Use a proper CDI ignition tester and make sure you have good spark you only have a few go arounds on the starter button before the plugs foul if the ignition isn't lighting it off pretty much right away.

  3. #3
    wkuadam07's Avatar
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    140 psi compression is fine... hard starting begins below 110, really bad below 100 psi.

    There isn't a separate fuel pump... The mag carb is the pump. If you have a separate fuel pump then your ski isn't stock setup and that's likely the problem. If your mechanic told you he rebuilt the pump separate, he more than likely doesn't know what he is doing. If the carbs aren't properly leak tested and set for pop off, the ski won't start in the water.

    Have you trimmed the spark plug wires? Do a search on that one, helps a lot with starting issues.

    Do you have a good fresh battery in the ski? Is the charging system working properly? Bad recifiers/voltage regulators make for hard starting problems...

  4. #4
    Yeah I do have good battery! And checked the rectifier has 12 volts then when started go into the 13teens. I did unplug the red and black wires. And it still ran the same. Just had the carbs rebuilt i I wonder if he put a diaphragm or something in backwards or if it just needs to be adjusted but it seems like it's getting a little too Much fuel. I had it on the lake today and sometimes I can get a start on water by holding the throttle wide open and turning it over for like a minute straight then there at the end it'll pick and start running but it's really boggy until it gets to high speeds. For instance I started it up and held it full throttle and it was only going at idle speed for about 100 yards until it picked up and took off

  5. #5
    GGG's Avatar
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    I had problems with those carbs being very rich. the fuel drains out of them when you shut it off making it flooded. try starting it at half throttle in the water after you run it for 30 sec or so, it should clear up

  6. #6
    Leave it strapped to the trailer in the water and see if you can adjust the idle speed / low jets to where it will start and idle correctly. Otherwise you will probably be taking the carbs back down.

  7. #7
    Check the rotary valve cover clearance. When they get out of spec, it will start right up on land, but not when the exhaust is under water

  8. #8
    I wound up totaling a 97 XP over that very issue. I had no idea that the rotary valve could to that. I even fuel injected it. Still no real change.

    It sucked

    Andy

  9. #9
    Quote Originally Posted by whittlebeast View Post
    I wound up totaling a 97 XP over that very issue. I had no idea that the rotary valve could to that. I even fuel injected it. Still no real change.

    It sucked

    Andy
    It can be a real head scratcher. Some mechanics don't believe it, but I ran into this with an HX. Replaced RV cover and all was well. You could even see the machined surface worn down.

  10. +1 by:

    GGG

  11. #10
    Mighty Mouse's Avatar
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    Starter spinning over fast is also important on the water. If you have a week starter that turns slow, may cause difficult starts on the water.

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