Page 1 of 2 1 2 LastLast
Results 1 to 10 of 19
  1. #1
    Tampa SeaDoo Crew TampaSpeedster's Avatar
    Join Date
    Sep 2009
    Location
    Tampa, FL
    Posts
    95

    Hesitation at high RPM (Pump or Engine?)

    Background: I have a 2008 Speedster 150 with an X-charger, and just installed a repitched RXPX prop. Top RPM with the new prop is 8060-8100... right on the money. Boat runs fantastic with the new mods.

    Problem: The only issue I'm having is hard to describe. When cruising at 7900RPM, it runs smooth as silk, no issues. When I peg the throttle for the last few MPH and RPM, it starts to "miss". If I had to describe how it sounded at wide open throttle it would be waaaaaaaaaaaaaaaaaaaaaaaaaaaaa - ba - waaaaaaaaaaaaaaaaaaaa - ba - waaaaaaaaaaaa - ba - ba - waaaaaaa. These "ba's" are happening about once every couple seconds. Seems to lose a couple MPH every hesitation. Doesn't feel like the limiter (and shouldn't be since I was all over 8200 with the stock prop), and doesn't sound like cavitation... since it happens in smooth water also.

    Things that came to mind:
    • Pump becomes unloaded at that RPM because the new prop is pushing out too much water at too fast of a rate?
    • Spark blowout - re-gap the plugs?
    • Intake grate starving the pump?
    • Etc
    Anyone else ever experienced anything like this? Any ideas?

    Thanks


  2. #2
    Having Fun jp1300r's Avatar
    Join Date
    Sep 2005
    Location
    Florida
    Posts
    5,334
    +1
    261
    Quote Originally Posted by TampaSpeedster View Post
    Background: I have a 2008 Speedster 150 with an X-charger, and just installed a repitched RXPX prop. Top RPM with the new prop is 8060-8100... right on the money. Boat runs fantastic with the new mods.

    Problem: The only issue I'm having is hard to describe. When cruising at 7900RPM, it runs smooth as silk, no issues. When I peg the throttle for the last few MPH and RPM, it starts to "miss". If I had to describe how it sounded at wide open throttle it would be waaaaaaaaaaaaaaaaaaaaaaaaaaaaa - ba - waaaaaaaaaaaaaaaaaaaa - ba - waaaaaaaaaaaa - ba - ba - waaaaaaa. These "ba's" are happening about once every couple seconds. Seems to lose a couple MPH every hesitation. Doesn't feel like the limiter (and shouldn't be since I was all over 8200 with the stock prop), and doesn't sound like cavitation... since it happens in smooth water also.

    Things that came to mind:
    • Pump becomes unloaded at that RPM because the new prop is pushing out too much water at too fast of a rate?
    • Spark blowout - re-gap the plugs?
    • Intake grate starving the pump?
    • Etc
    Anyone else ever experienced anything like this? Any ideas?

    Thanks
    First thing I would is try putting NEW NGK sparkplugs in.

  3. #3
    Tampa SeaDoo Crew TampaSpeedster's Avatar
    Join Date
    Sep 2009
    Location
    Tampa, FL
    Posts
    95
    Quote Originally Posted by jp1300r View Post
    First thing I would is try putting NEW NGK sparkplugs in.
    I will do it since it's cheap, but these plugs have < 2hrs of use on them.

  4. #4
    Having Fun jp1300r's Avatar
    Join Date
    Sep 2005
    Location
    Florida
    Posts
    5,334
    +1
    261
    2hours.

  5. #5
    Having Fun jp1300r's Avatar
    Join Date
    Sep 2005
    Location
    Florida
    Posts
    5,334
    +1
    261
    Did you just put the x-scer on? Did you do anything with your fuel? I mean did you add fuel? Maybe lean at MAX WOT. Do you ride in saltwater? Maybe check your coils real good and try someone elses coils in your boat and see if it straighten out.

  6. #6
    Tampa SeaDoo Crew TampaSpeedster's Avatar
    Join Date
    Sep 2009
    Location
    Tampa, FL
    Posts
    95
    Quote Originally Posted by jp1300r View Post
    Did you just put the x-scer on? Did you do anything with your fuel? I mean did you add fuel? Maybe lean at MAX WOT. Do you ride in saltwater? Maybe check your coils real good and try someone elses coils in your boat and see if it straighten out.
    Coils are a good idea, I will check those. I have installed 42lb injectors so fuel should be spot-on. I ride in Saltwater nearly 100% of the time.

  7. #7
    Doel Tiburon1264's Avatar
    Join Date
    Nov 2007
    Location
    Jacksonville, Florida
    Posts
    2,343
    +1
    11
    I think is asking for more Fuel in WOT. I will check and do a visual inspection on Gas Pump and Gas Tank to ensure nothing is in the filter, tank and fuel lines.

  8. #8
    richrxp's Avatar
    Join Date
    Jun 2006
    Location
    Netherlands
    Posts
    949
    +1
    1
    Quote Originally Posted by Tiburon1264 View Post
    I think is asking for more Fuel in WOT. I will check and do a visual inspection on Gas Pump and Gas Tank to ensure nothing is in the filter, tank and fuel lines.
    That's exactly what i was thinking.
    You better know what afr you have at wot.
    Maybe the 42's aren't enough,run a fuelcontroller ,or a rrfpr.
    But first measure your afr!!!!

  9. #9
    Tampa SeaDoo Crew TampaSpeedster's Avatar
    Join Date
    Sep 2009
    Location
    Tampa, FL
    Posts
    95
    Quote Originally Posted by richrxp View Post
    That's exactly what i was thinking.
    You better know what afr you have at wot.
    Maybe the 42's aren't enough,run a fuelcontroller ,or a rrfpr.
    But first measure your afr!!!!
    Well, it just doesn't make sense since my buddy has the EXACT same setup and his goes like stink all day long. I had this issue every now and then on the stock setup also... maybe my fuel filter is shot (I've never replaced it). Really dont want to get into RRFPR or wideband stuff if I dont have to.

  10. #10
    TheElite0ne's Avatar
    Join Date
    Jan 2009
    Location
    Tampa, FL
    Posts
    383
    +1
    20
    Quote Originally Posted by TampaSpeedster View Post
    Well, it just doesn't make sense since my buddy has the EXACT same setup and his goes like stink all day long. I had this issue every now and then on the stock setup also... maybe my fuel filter is shot (I've never replaced it). Really dont want to get into RRFPR or wideband stuff if I dont have to.
    confirmed

Page 1 of 2 1 2 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Replies: 7
    Last Post: 05-31-2015, 06:58 AM
  2. 96 sl-780 Missing on pto cylinder at high rpm
    By gvnitup in forum Polaris Open Discussion
    Replies: 8
    Last Post: 08-25-2009, 10:26 PM
  3. engine sputters at high rpm
    By nitroguy in forum Yamaha PWC Performance (2-stroke)
    Replies: 4
    Last Post: 07-08-2009, 06:43 PM
  4. XL1200 cavitation at high RPMs
    By jamie327 in forum Yamaha PWC Performance (2-stroke)
    Replies: 13
    Last Post: 03-19-2009, 07:17 AM
  5. 99 GTX Ltd Cutting out at high RPM
    By Picturemn2 in forum 2-Stroke Performance
    Replies: 8
    Last Post: 09-28-2007, 04:55 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •