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  1. #1

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    Genesis Fuel Injected - low power, running rough at mid throttle

    Hi,

    Ive just bought a Genesis Fuel Injected Jet Ski. It worked great for the first half hour I had it, just driving straight up and down a large open area, calm water, and then after doing sharper turns, figure 8's etc the engine seemed to lose power.

    Before it was doing 55mph, and after it now only does about 40mph. Full throttle is reaching at most 5500 rpm.

    In the mid range throttle the engine runs a little rough, seems like its missing.
    It starts perfect and idles well
    There have been no engine warning lights on.
    The ski has done 150 hours, it hasnt been used for about the last 5 years until I bought it a week ago and used it for the first time this weekend.


    I have looked at the following:
    • Fuel pressure is 22psi
    • Engine compression is 135psi on two cylinders, 137 on the other.
    • Ive been keeping an eye on engine temp, it seems ok, after a full throttle run I can stop the engine and am able to touch the cylinder heads no problems.
    • The spark plugs are dirty, in particular cylinder 3 is much dirtier than the others. The spark plug on cylinder 3 also has a dry spot on the insulator with what looks like an orange burn mark around the dry spot (the rest of the plug other than this area covered in oil)
    • The ignition lead on cylinder 3 doesnt click in like the others do, it is going on all the way, it just doesnt have the click as the others do.
    • The inside of the caps of the ignition leads are dirty and oily, cleaning the spark plug, i click it into the lead, pull it out and its covered in what seems to be oil or something. Have done my best to clean the leads, made no difference.
    • The jet intake grille is clean
    • The impeller has a small chip missing from the edge of one of the blades, about 2-3 mm deep where is seems to have hit something, I don't think that small mark is the issue here.
    • Air filter is nice and clean
    Am I correct in thinking if it has 22psi return fuel pressure then anything fuel related is not the issue? fuel pump/regulator/fuel filter can all be ruled out as there is sufficient fuel pressure? I would have been initially leaning to a fuel issue as it worked well, did some sharp turns and then lost power. So i thought maybe disturbing some dirt or something in the tank and sucking it through could have caused the issue. With the 22psi return fuel pressure, it doesnt seem to be an issue with the pump or fuel filter?

    Could any junk get caught in the injectors? Is it easy to remove the injectors and check if they are working properly and not blocked in any way?

    I have seen people talk about the fuel hose saying it should be replaced with a better one? Should I be doing this?

    I will be buying new spark plugs and leads probably today and see how it goes. Im hoping this is the issue... however im not sure. The fact it was working for half hour then all of a sudden went bad and has been the same since, make me think something else other than spark plugs.

    When I replace the leads I will remove and clean all the connections onto the coil to make sure the wires havent got any corrosion on them.

    What would you suggest I start looking at to diagnose the issue? Hoping to have it fixed before the weekend.. so I have 5 days left to get it fixed haha.

    Thank you!!


  2. #2

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    I replaced the spark plugs and leads yesterday, and unfortunately as i suspected it didnt change a thing. Performance is still exactly the same.

    Does anyone have any suggestions on what to look at next?

  3. #3
    David Drkvampire2001's Avatar
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    Who really needs to chirp in, is K447 he knows these machines like the back of his hand, I am just learning these machines so take it with what you will. Most of what I see of issues with the FI skis, are the EMM, or the Throttle Position Sensor. I am unsure of the symptoms that would cause your exact issue, but , until the return of K447 Check around the link posted in my signature, im sure we will get to the bottom of this.

  4. #4
    ripcuda's Avatar
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    Welcome to GH! You've sadly come at the start of the off-season... so not as much traffic around this time of year.

    I too have just begun spooling up my Direct Injection knowledge... having just picked up my first D.I. recently.

    So I'll throw out some ideas and questions... that'll surely get the gurus to show up and correct me!

    First off... lots of info here to start with: http://polarispwcknowledge.shorturl....jected-engines

    What spark plugs are you using? Make sure you use only NGK PZFR6H.

    Here's fuel pressure info from the Ficht Master, K447:
    Fuel pressure check is done at the schrader valve tee in the return fuel line. Should be over 20 PSI and stable. The electric fuel pump inside the fuel tank is turned on when the EMM see the engine is cranking or running.

    A further test is to clamp the fuel line between the schrader valve tee and the fuel tank. Fuel pressure should rise to about 30 PSI with the return line clamped (hose pinch pliers), and return to just over 20 PSI with the clamp removed.
    What was your fuel level at when you did the figure 8's and noticed the issue?

    Are you using fresh fuel? Old gas (or possible water contaminated) could cause issues...

    Check your grounds and battery leads. Ensure clean and tight.

    What was the max RPM you saw when it was running "right" (at 55mph)?

    The TPS (throttle position sensor) is a common issue... search the link above on how to adjust/set it and see if that helps. Might be going bad.

    What does the piston wash look like? Any signs of running lean?

    Pull the jet pump. Does the impeller spin freely? Slight imperfections in the impeller edges or stator edges will affect performance and top speed a tad... but won't cause the issues you describe.

    My last thought... would be the EMM (engine brain). These Ficht EMMs do seem to have internal components that are reaching the end of their service life (based on the age of the Ficht skis)... and when they start failing... the EMM starts mis-behaving and causing running/idling/starting issues. Thankfully they are repairable...

    Hope that helps. That PWC Knowledge bank link I gave above will be your most valuable info source... apart from K447!

    Cheers!

  5. #5

    Join Date
    Nov 2014
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    Thanks for the replies guys!

    We are just getting into Summer here

    The TPS is high on my list to test as well as testing all grounds.

    We had a full tank when we did the figure 8's.
    The tank was pretty low when I bought the Jet Ski, so it has pretty much a full tank of new fuel.

    Im not sure what the RPM was, I didnt look at it until later in the day when it wasnt running well.

    Both the old and new plugs are correct.

    How can I check piston wash? Only way I can think of is to take out the spark plugs and use a camera with flash to see down the spark plug hole?

    Throttle response seems alright up until about 2/3 pr 3/4 throttle where i increase throttle yet the engine seems to almost lose power, until i get to full throttle and power comes up slightly.. seems like full throttle is only slightly more powerful than 3/4 throttle, yet between 3/4 and full is less power than 3/4. From what I know (in general about engines, not specific to these) that could be caused by a throttle sensor, the ecu not knowing the throttle butterfly is as open as it is and therefore not giving enough fuel... im hoping thats it. Will see when I test the TPS

  6. #6
    Banned User
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    You will not find any piston wash on a DI. The fuel does not come in through the crankcase

  7. #7
    Click avatar for tech links/info, donation request K447's Avatar
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    Welcome

    I have been otherwise occupied recently...

    While it is possible to bench test a TPS (controlled voltage test, not ohms), the results are often inconclusive. A TPS can test 'good' with a meter, yet actually be bad when bolted to a vibrating, hot, running engine.

    The reliable test for a TPS is to install a new or known good TPS. If the problem goes away, the old TPS was bad.

    If the problem remains, then you now have a spare TPS, which is a good thing. There is no work around for a suspect TPS, so having a spare on hand can be really useful.

    Piston wash is mostly a carburetor engine thing, but it can be inspected. On a carb engine you just remove the spark plugs and use a tiny inspection light plus your eyeball down through the spark plug hole (with crank rotated to move each piston to BDC).

    On a Ficht engine you must remove the fuel injectors to see down into the cylinder. The fuel injector hole is smaller than a carb engine spark plug hole so it is still difficult to clearly see the piston top, even with a large towel or blanket covering your head and blocking out the sunlight. I use a thin ProVision bore scope.

    A normally operating Ficht engine will have fairly small piston wash pattern areas around the perimeter of the piston. On a carburetor engine this would be considered minimal wash, on Ficht it is normal.

    Wash patterns reflect recent engine operation, so if the engine spent a lot of time at low RPM or idle then the wash pattern may be misleading. Proper wash patterns are the result of mid to high power range running, at speed on the water.

    There are no user accessible adjustments for fuel richness on a Ficht engine, so piston wash pattern is not as directly useful as on a carb engine.

    Engine RPM at full throttle, in the water, running at speed, is the primary method of verifying full engine power. If the RPM range is below normal at wide open throttle then the power is low. A nicely running red Ficht engine will turn about 6500-6700 RPM, depending on air temperature, passenger load, jet pump condition, etc.

    Make sure the replacement high tension spark plug wires are the correct ohms resistance. The Ficht ignition system is very picky about spark plugs and wires.

    Check, or even better, remove and clean the grounds for each ignition coil. I have posted how to relocate the fiber washers so the coil tab is in direct contact with the cylinder head mounting boss. Do not delete the fiber washer, it is important to allow for vibration and heat expansion. You want clean metal to metal contact to ensure a solid grounding for each coil.

    If there is a ground wire from the harness at the ignition coil, make sure that is also a clean and solid ground.

    I understand you have checked fuel pressure and it seems to be in range. Even so, the factory mounting for the pressure regulator is known to be weak and the regulator can fall out at any time. I suggest it is worthwhile to inspect the regulator mounting inside the top of the fuel tank. If it has not yet been strengthened then it should be done.

    I have posted elsewhere how to reinforce the fuel pressure regulator mounting using a threaded NPT nipple.

  8. #8

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    Today I replaced the old original TPS with the new model TPS. Unfortunately it has made it worse.. Top speed is the same 40mph, however when at partial throttle the engine bogs down, about a third to a half throttle it picks up again, until about 3/4 throttle where it bogs a little again until full throttle it picks up slightly. I think it's a 2000 or 2001 model. I removed the old TPS, removed the nut from the shaft and removed the washer and lever. I fitted the new sensor with a few washers to space it out from the throttle body.

    Is is there any adjustment to be done on the tps?

  9. #9
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by clint View Post
    Today I replaced the old original TPS with the new model TPS. Unfortunately it has made it worse.. Top speed is the same 40mph, however when at partial throttle the engine bogs down, about a third to a half throttle it picks up again, until about 3/4 throttle where it bogs a little again until full throttle it picks up slightly. I think it's a 2000 or 2001 model. I removed the old TPS, removed the nut from the shaft and removed the washer and lever. I fitted the new sensor with a few washers to space it out from the throttle body.

    Is is there any adjustment to be done on the tps?
    Well, you can check the voltage signal coming out of the TPS. Find a way to tap into the TPS wires while it is connected.

    Use a Service Power Jumper (at the 8-pin EMM wire harness connector) to power up the EMM with the engine not running. Now you can check the voltage coming out of the TPS at idle and at full throttle.

    EMM provides a precise 5.0 volts DC to power the TPS.

    Idle will be between 0.350 and 0.4xx volts.
    Full throttle will be 4.xx volts (I forget the exact number at the moment, but I have posted it elsewhere)

    Also check how much mechanical slop there is between the throttle cable arm at the front and the third throttle body shaft at the rear. Sometimes the links between the throttle shaft sections can get sloppy.

  10. #10

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    So an update...

    I booked it into a local shop, one to get a good service and check over as ive just bought the ski, and secondly to fix the issue.. $600 later i have the ski back and its still not fixed. It is however better now, but is intermittent. Before it wouldnt get above 5500 at all, now it will intermittently. The shop did a general service, replaced the fuel tank oring, fixed a fuel leak on injector 3, and removed and cleaned the coils, and made sure they had good grounds.

    When I first start the engine, for maybe the first 5 or 10 mins most of the time it works perfect, it hits 6,500 rpm. Strangely though, its either good or bad, nothing in between, and stays one or the other for as long as I hold the throttle on.

    in this first 5-10 mins if i hit the throttle and it revs to 7000 then drops back to 6500 as it gets speed, it will stay at 6500 for as long as i hold full throttle. When i get off the throttle for a few seconds and go to get back on it, some of the time it will only hit 5500 rpm, and other times will hit 6500 rpm. If it hits 5500 rpm, same thing, as long as i hold full throttle it will stay at 5500rpm. ive been tracking speed with gps, it always is constant, exactly 61km/h at 5500rpm or 79.5km/h at 6500rpm. it either does one or the other, never anything in between.

    When it does 5500rpm within the first 10-15 mins, a quarter throttle has more power than full throttle, as i increase throttle i can feel the engine bog down. if i get off the throttle, slowly get on it, slowly increasing i can feel and hear the engine is great, and at a point it will bog and go bad, at that point i back off a bit, and slowly come back up on the throttle, and often within the first 10-15 or 20 mins i can slowly bring the throttle up backing off when it bogs and bring it up more until im at full throttle where it will stay for as long as i hold throttle.

    After i rode for an hour yesterday, i parked up on the beach for 10 mins, when heading out it was no better, stuck at 5500rpm no matter what i did with the throttle, so I am assuming heat is affecting performance here.

    After half hour or so of riding, nothing i do will get it running well, up to a quarter throttle bogs unlike earlier where up to a quarter would sound and feel great and have more power than full throttle when not running well.

    Any thoughts on what to do next? I am about to go out now and buy new coils to try and see if that fixes it. Im wondering if its a weak coil or something, and bringing on full throttle instantly, is too much for the coil, slowly increasing rpm and load is alright on the coil, until its at full throttle and as it was ramped up the coil could deal with the rpm ramping up compared to idle to full rpm with full load on the engine. Maybe the coils performance is also decreasing with heat, explaining why after the engine is warmed up, shutting off for 10 mins and starting again didnt make it good again.

    I am only guessing with what little knowledge I have here, so any other ideas would be great.

    Thank you!

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