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Thread: MSX150 no start

  1. #1

    MSX150 no start

    Hello, fellow Polarisers (I don't think that's a real word):

    Okay, I am at a standstill with my lski knowledge. I had to take the engine out tof my 2004 MSX150 in order to replace my cracked exhaust pipe. The engine came out with ease, pipe replacement was effortless, and the engine went back in easy as pie, or cake, or whatever serves as your favorite dessert(Grin).

    I should have remembered the old addage: If it seems too good to be true . . .

    After all was back together, fluids were brought to factory specs. I was careful to avoid over filling the oil level (an ongoing danger, as we MSXers know all too well).

    After battery was topped up, and I tried to start the engine, I was immediately in a no-start situation.

    So far I have verified (using my handy-dandy 2004 Polaris Service Manual) that the engine has:

    1. Good compression in both cylinders
    2. Good spark from both
    3. Injectors are clicking normally while cranking
    4. Fuel pump pressure is exactly at factory spec

    The ski ran beautifully before the pipe got cracked. Right up to when I took the engine out, the engine ran normally, with the exception of loosing boost presssure through the crack, and therefore limited the WOT to 4800-5200 RPM. Basically it ran fine.


    I tried a little fuel in the cylinders, and it started immdeiately when I pushed the start button . . . and it died immediately when the fuel in the cylinders was used.

    Sooooo, It appears as though the fuel is not getting past the fuel regulator and/or fuel rail.

    I was looking at the regulator, thinking that perhaps it was loosing its vacuum.So that's where I am.

    Anyone have any ideas.

    Thanks


  2. #2
    Kosh's Avatar
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    Hello fellow owner,

    I guess you know it will not start if the battery voltage falls to low while cranking?

    The vacuum line to the regulator is there to increase fuel pressure as the boost rises no need to worry about that at the moment, The regulator could be faulty and not letting the pressure build up but this is very unlikely.
    A quick test to see if the fuel system is working is remove the two screws holding the injector rail in place and carefully pull it out (make sure it is clean around the injectors, don't wont any foreign material getting in) you can do this without disconnecting a thing. Put a piece of paper in front of the injectors and crank away, you should see the fuel pulsing out. Of course this is a flammable mixture so take precautions.
    If you are seeing fuel this stage this indicates that the ignition system is also powered up.
    I have run a hundred steps ahead, we can backtrack if you have no fuel.

    Make sure you have the front rotational sensor plugged back in.

    Cheers
    Last edited by Kosh; 06-05-2009 at 05:08 PM. Reason: Aother thought

  3. #3

    MSX150 no start

    Thanks for the reply:

    Unfortunately (and embarassingly), I must admit that I've never heard of a "front rotational sensor." I did searches in my service manual, and nothing comes up by that name. Could it possibly have another name?

    If not, could you just tell me where it is and what it basically looks like?

    Thanks again

  4. #4
    ph2ocraft's Avatar
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    Did you have any wires off the harness that didn't get attached?

    The speed sensor is number 4 and the wire comes up inbetween the intake manifold and the head.

  5. #5

    MSX150 no start

    Ph2ocraft:

    Thanks for the clarification on the "front rotational sensor." In my manual the sensor you identifed is called a "Engine Speed Sensor" in one place and a "Crankshaft sensor" in another. In any case, I checked it, and it is indeed plugged in.

    Following Kosh's reply (after determining that spark and fuel pressure were both within factory range), I seem to have come to the specific problem. Although the injectors make their standard clicking sound when the engine is cranked, no fuel is coming from the the injectors. Fuel is getting to the injectors, just not OAST the injectors.

    Just a recap of stats:

    1. Battery is at 100%. Even if I crank the engine for more than a minute or so, I am making certain the battery charge doesn't drop below 95% by recharging it immediately before proceeding.

    2. Fuel pressure is in line with manual specs. 44.1 psi at idle

    3. Spark is strong in both cylinders. I added a small amount of fuel through the injector holes, and the engine fired right up, then died as that fuel was used up.

    4. Compression is 136 in cyl 1 and 140 in cyl 2 - both in spec range.

    Prior to removing the engine, there was no problem with the injectors at all, or with anything at all other than the cracked exhaust pipe I took the engine out to replace.

    Do you--or anyone!--have any ideas on my next step.

    Thanks again.

  6. #6
    Kosh's Avatar
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    FLN,
    Sounds like you are almost there. My guess is that the battery voltage is dropping to low. I beleive, and am open to correction that the fuel is cut if the votage drops to low not the spark.
    It may pay to try a another battery as a dicey one will give you the symptoms you describe. Are you measuring the voltage while cranking?
    Have you had the spark plugs hooked up externally and witnessed them sparking? Should be a real good strong spark. Probably not nessesary as you say it will run on externally added fuel. Just another check.

    If the spark plugs are firing this indicates the injectors are receiving + voltage. The computer switches them to ground to activate them.

    It should be running

    Sorry for the bum steer on the front rotational sensor. I will make sure I stick with convention in future.

  7. #7
    Rocky_Road's Avatar
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    I agree, Kosh...about the battery.

    Before I bloodied my head (beating it on the wall), I would drop a new battery into this ski...and eliminate that question mark!

    Batteries are fickle...and impossible to diagnose with just a volt meter!

  8. #8

    MSX150 no start

    Thanks for the replies, guys:

    Like I said in my last reply, I'm being very diligent about keeping the battery at 100%. I've never even tried to start the engine with the voltage below 12.4. It is Definately NOT the battery causing my problem. In fact, I just bought it a month ago, and I've only used it during the past week while dealing with my no start problem. I got the battery new, and it still had a 90% charge from the store. I topped it up before its first use, and I've never let it get below 90% before stopping my cranking and recharging it.

    Any ideas why both injectors aren't firing (or spraying, would be more accurate, I suppose)?

    One other side note. I couldn't find a decent diagram for the wiring that goes to and from the solenoid. I posted the question and everyone agreed that the starter connection is on one post all by itself, while the other two wires go to the other solenoid terminal (I'm not including the dual-wire plug that plugs into the bottom of the solenoid in this dicussion. It's plugged in correctly). I'm not having any problems cranking, but both my manual and everyone who replied to my question say there should be two wires on the non-starter side, as does the diagram in my manual. On the battery side terminal, I have the standard heavy red cable coming from the battery, and a smaller red wire with a connection loop on it.

    BUT, I have another red wire with a factory connection loop on it. The respose to this was to put this "other" wire on the battery-side solenoid terminal, so that what I ended up with, was one heavy red cable from the starter on one side, and the other heavy red battery cable and two smaller connections on the battery-side terminal.

    But it seems odd to me that there should be another red cable not shown in the solenoid diagram. No one on greenhulk could tell me what this other red wire is for, just that it goes with the others on th ebattery side. That bugs me (not the people's responses, everyone's been great). It bugs me because no one knows what this third wire is.

    Any ideas on that? Any possible connection to my injector problem?

    Thanks again.

  9. #9

    MSX150 no start

    Thanks for the replies, guys:

    Like I said in my last reply, I'm being very diligent about keeping the battery at 100%. I've never even tried to start the engine with the voltage below 12.4. It is Definately NOT the battery causing my problem. In fact, I just bought it a month ago, and I've only used it during the past week while dealing with my no start problem. I got the battery new, and it still had a 90% charge from the store. I topped it up before its first use, and I've never let it get below 90% before stopping my cranking and recharging it.

    Any ideas why both injectors aren't firing (or spraying, would be more accurate, I suppose)?

    One other side note. I couldn't find a decent diagram for the wiring that goes to and from the solenoid. I posted the question and everyone agreed that the starter connection is on one post all by itself, while the other two wires go to the other solenoid terminal (I'm not including the dual-wire plug that plugs into the bottom of the solenoid in this dicussion. It's plugged in correctly). I'm not having any problems cranking, but both my manual and everyone who replied to my question say there should be two wires on the non-starter side, as does the diagram in my manual. On the battery side terminal, I have the standard heavy red cable coming from the battery, and a smaller red wire with a connection loop on it.

    BUT, I have another red wire with a factory connection loop on it. The respose to this was to put this "other" wire on the battery-side solenoid terminal, so that what I ended up with, was one heavy red cable from the starter on one side, and the other heavy red battery cable and two smaller connections on the battery-side terminal.

    But it seems odd to me that there should be another red cable not shown in the solenoid diagram. No one on greenhulk could tell me what this other red wire is for, just that it goes with the others on th ebattery side. That bugs me (not the people's responses, everyone's been great). It bugs me because no one knows what this third wire is.

    Any ideas on that? Any possible connection to my injector problem?

    Thanks again.

  10. #10
    Click avatar for tech links/info, donation request K447's Avatar
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    Regarding the smaller red wires; The wiring diagram in the Polaris MSX 150 service manual is terrible. Not a proper wiring diagram, as far as I am concerned. Looks more like assembly instructions or an electrical 'plumbing' diagram

    If somebody has an actual, proper wiring diagram (electrical schematic) for the Weber engined Polaris PWC, let me know

    When the engine is cranking, the two heavy terminals of the solenoid are electrically connected together. That is what the solenoid does - connects battery power on one terminal stud to the starter motor cable on the other stud.

    Even if one of the thinner red wires was on the 'wrong' solenoid post, while it is cranking it would still fire up and run the engine, right until you let go of the start button

    Batteries can be defective right off the store shelf.

    The test of a battery is not the no-load voltage. That can tell you the state of charge (charge percentage), but not the strength or 'internal health' of the battery.

    The real test for a starting battery is how much voltage it can deliver while the engine is cranking. That is the test that really matters.

    Put your multi-meter on the battery posts, and crank the engine. How low does the voltage drop?

    A healthy battery should be able to deliver 11.0 volts or better while cranking. A marginal battery will deliver something over 10.5 volts (the higher the better).

    A weak battery will allow the voltage to drop below 10.5 volts while the engine is cranking.

    If the battery has been recently charged, and it still can not keep the voltage up while cranking, the battery is no good. Even if it is brand new.

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