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Thread: Engine surging

  1. #1

    Engine surging

    Okay, as usual, I need some help. My MSX150 was going great. Went out today and the engine began surging up and down, and it pretty much wouldn't do anything else. I am now very familiar withthe fuel system thanks to my previous problem; but after that, I will never say I'm 100% certain on anything about this ski ever again.

    So, any ideas on surging. It seems like it's a fuel problem, but I'm getting 43 PSI from the supply hose, fuel is going back to the tank via the return hose. It does it at idol and cannot seem to get past the surging to get ABOVE idle. It makes no difference if it's in the water moving or sitting on the dock in idol, so I don't think it has anything to do with the pump drive.

    Fuel pump maybe? But how, if I get pressure how could it be?

    If it is the fuel pump, can you I rebuild one from a kit, or do I have to spend the nearly $400 list price for a new one?

    Thanks


  2. #2
    SPEED KILLS, BUT YOU GET THERE QUICKER Keddano's Avatar
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    The pro's with the 150's will jump in, The pump per say are not rebuildable,but I should have one lying around from my conversion if you find that is it.

  3. #3
    Kosh's Avatar
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    Good day FLN,
    I have experienced something similar to this fault when the MAP sensors were contaminated with oil. My suggestion as a place to start is pull both sensors and check them out, they both should be dry. Run the multimeter over the pins and check them against specification. They are both the same so are interchangable. If they are contaminated it probably means that the oil is overfull.
    If these are OK you may have an air leak below the throttle body or intake manifold to head join and the throttle is trying to compensate.
    Let us know what you find.
    Cheers
    Attached Files Attached Files

  4. #4

    over filling oil

    I put to much oil in the msx 150 and ran it a short time. Drained the oil off and now the engine surges and the red light comes on. Once I turn off the machine the red light goes off at the next start up and I am fine for awhile. What and where are the map sensors-they were probably contimated with oil. Any ideas on what to do? thanks jc
    Last edited by jimbob23; 06-24-2009 at 09:06 PM. Reason: more info

  5. #5
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by jimbob23 View Post
    I put to much oil in the MSX 150 and ran it a short time. Drained the oil off and now the engine surges and the red light comes on.

    Once I turn off the machine the red light goes off at the next start up and I am fine for awhile.

    What and where are the map sensors-they were probably contaminated with oil. Any ideas on what to do? thanks jc
    Welcome to the Hulk

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  6. #6
    desperado's Avatar
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    95% probability the MAP sensor is bad. It causes the ECU to "think" the engine is under a different load than it actually is and the electronic throttle body hunts in an effort to align itself with the erronous engine load reading -- causing the rpm surge and hunting.

  7. #7

    Engine Surging Continued.

    Thanks for all the info guys (and I mean that generically, of course. No women-haters in MY home):

    So far, I have tested the Air Temp/Boost pressure Sensor, the intake pressure sensor, the wastegate pulse valve solenoid, and the DC motor part of the ETB. Here's what I got:

    Air Temperature – Boost Pressure
    Good Range Actual
    Pins 1 and 2 - Air Temp (2.5KΩ@68º): 1.72Ω .78Ω low
    Pins 1 and 4 - Pressure (2.4Ω - 8.2Ω): 3.8KΩ
    Pins 3 and 4 - Pressure (2.4Ω - 8.2Ω): 5.22KΩ

    Manifold Pressure Sensor
    Good Range Actual
    Pins 1 and 4 - Pressure (2.4Ω - 8.2Ω) 5.64KΩ
    Pins 3 and 4 - Pressure (2.4Ω - 8.2Ω) NO READING

    Wastegate Pulse Valve Solenoid
    Good Range Actual
    28.5Ω - 32Ω 23.5Ω

    Electronic Throttle Body (DC Motor resistance only)
    Good Range Actual
    DC Motor Resistance 1.5Ω +/- .3 1.6

    Still working on TPS voltages.

    This is the way I understand my results. Please tell me if I'm not interpreting the data properly.

    With no reading on pins 3 and 4, obviously the Manifold Pressure Sensor is bad.

    The air temp reading on the boost pressure/air temp sensor is .78KΩ low (and yes, I tested it at exactly 68 degrees). But is this enough to call the sensor BAD?

    Both pressure sensor resistance readings on the boost pressure/air temp sensor are within range, so they appear to be acceptable.

    And lastly, there is the wastegate pulse valve solenoid, which is reading exactly 5Ω too low. BAD.

    Recap: Manifold pressure sensor: BAD

    Air Temp/boost pressure: okay boost-wise, but temp
    resistance too low. Don't know if it's GOOD or BAD.

    Wastegate Pulse Valve Solenoid: 5Ω too low: BAD

    DC Motor on ETB has resistance of 1.6Ω . Okay.

    Is this all correct, I really hate to buy stuff I don't need. Anyone's and everone's feedback would be appriciated.

    Thank you.

  8. #8

    Please help with sensor reading, I'm stalled

    A little help, Please, please, please HELppppp!

    Could someone look at the above readings and tell me if my conclusions are correct?

    Heeeeeelllppppp!!!

    FLN
    P.S. -----You can also email me at [email protected]

  9. #9
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by desperado View Post
    95% probability the MAP sensor is bad...
    Quote Originally Posted by freelancenovelist View Post
    ...Manifold Pressure Sensor
    Good Range Actual
    Pins 1 and 4 - Pressure (2.4Ω - 8.2Ω) 5.64KΩ
    Pins 3 and 4 - Pressure (2.4Ω - 8.2Ω) NO READING

    ...With no reading on pins 3 and 4, obviously the Manifold Pressure Sensor is bad.

    The air temp reading on the boost pressure/air temp sensor is .78KΩ low (and yes, I tested it at exactly 68 degrees). But is this enough to call the sensor BAD?

    ...And lastly, there is the wastegate pulse valve solenoid, which is reading exactly 5Ω too low. BAD.

    Recap: Manifold pressure sensor: BAD

    Air Temp/boost pressure: okay boost-wise, but temp
    resistance too low. Don't know if it's GOOD or BAD.

    Wastegate Pulse Valve Solenoid: 5Ω too low: BAD

    ...I really hate to buy stuff I don't need...
    Are these parts expensive?

    We don't have many Weber engine guys around, so it can take a while before you get another answer.

    If the parts costs are not un-reasonable, you may be better off to go ahead and order them.

    You can just start with the MAP sensor. If that doesn't entirely fix the problem, then order another part. Takes longer that way, of course.

  10. #10
    2&4strokepolaristech's Avatar
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    ok I have been waiting for someone to ask you a few key questions but I don't see it posted so here I go:

    Did you ever have both sensors unpluged at the same time? Maybe to clean the sensors or the intercooler? Did you replace the wiring harness or have the engine out ever? When is the last time it ran good?

    The reason I ask is because you can switch the two plugs for the sensors and it will surge and pop and miss. Make sure that the 4 terminal plug(wires) is on the top sensor(tube from intercooler to ETB. Make sure that the 3 terminal plug(3 wire) is in the intake manifold.
    Let us know how you make out.

    Jay

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