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  1. #1
    Member
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    Mar 2015
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    Bixby, OK
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    HPDI Starting Issue

    I have an 08 200 HPDI that has been giving me trouble for a few months now. First start it fires right up, runs for 2 or 3 seconds and dies. I have to hold the hot foot down about half way or so to get it to start again, then let it idle at 2 to 3k for a few seconds to keep it running. At idle, it spits every now and then like it's mis firing, both in neutral, and in gear. If I give it just a little gas, 200 rpm or so, it smooths out and is fine. Runs perfect on plane. Sometimes it will fire right up every time the rest of the day, sometimes it won't and I have to give it gas to keep it running.

    Here's what I've done so far, changed spark plugs, VST filter and the other filter in the plastic bowl that screws on, changed primer bulb and low pressure pumps, injectors serviced a year or so ago and mystery filters replaced at that time.

    For what it's worth, VST was perfectly clean when I had it apart. Port side spark plugs all looked great, starboard side were not as clean, and the top one was super dirty.

    Any ideas?

  2. Member
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    Jul 2020
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    Lake Travis - Spicewood, TX
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    131
    #2
    Subscribed -Looking forward to any suggestions offered.

    Exact Same issue here on new to me 06 225 HPDI. Replaced all engine fuel filters, low pressure pumps and onboard spin-off filter. VST and everything looked clean. Even installed new onboard fuel canister because the water sensor went bad. Planning to pull the plugs tonight to check for fouling. Based on other posts: (1) going to pull my onboard canister, freeze it an reinstall to ensure fully seated and no leak; (2) going to check plugs tonight (they were installed when I bought the boat - I have a new set ready, but if fouled, don't want to ruin the news one if a fuel issue will just ruin them too); (3) I was told the prior owner ran Quick Silver Premium Plus, so I have been too - I may drain what's in the tank and swap to Pennzoil Premium Synthetic based on others saying it runs cleaner; (4) Was thinking about sending my injectors for service, but it runs perfect once above about 900 rpm, so not sure that is the issue (sounds like it did not solve yours). Also, when I replaced the filters, the oil pump mystery filters were in place, and the injector filters had been removed - one mechanic told me he does not run the injector mystery filters in his HPDI. I went ahead and put new ones in to be safe. To me it seems like the engine is running about the same or maybe worse. I am considering pulling the injector mystery filters to see if there is any improvement. Based on everything I read, it just seems like the engine has trouble pulling fuel when idling and any restriction causes a rough idle. Once going, the engine is able to pull fuel (so far, no issues while running - knock on wood). It seems to me that the best fix would be to set the idle 100 rpm higher, but everything I read suggest it is not straightforward or good for the engine (or shifting).

    Please report back with anything and I will do the same.

  3. Member
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    Feb 2018
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    Spirit Lake, Iowa
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    #3
    Check the atmospheric pressure sensor is plugged in (it is the sensor on the bottom side of the VST bracket, I forgot to replug mine after doing a filter change), and check the throttle position sensor output voltage via YDS. Also, make sure the electric fuel pump in the VST is operating properly. I have heard that the electric fuel pumps can fail, causing a rough idle, but when wound up, the mechanical pump takes over and everything smooths out.

  4. Member
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    Jul 2020
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    Lake Travis - Spicewood, TX
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    #4
    Quote Originally Posted by Thamelau View Post
    Check the atmospheric pressure sensor is plugged in (it is the sensor on the bottom side of the VST bracket, I forgot to replug mine after doing a filter change), and check the throttle position sensor output voltage via YDS. Also, make sure the electric fuel pump in the VST is operating properly. I have heard that the electric fuel pumps can fail, causing a rough idle, but when wound up, the mechanical pump takes over and everything smooths out.
    Thanks. What voltage range are we looking for on the throttle position sensor? Does YDS have an indication of whether the electric fuel pump in the VST is operating properly?

  5. Member
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    Feb 2018
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    Spirit Lake, Iowa
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    #5
    The voltage range is .60V +/-.02 volts. It is kind of a pain to adjust until you get the hang of it. YDS can tell the electric fuel pump to run, but you will need to hook a fuel pressure gauge to the schrader valve on the VST to see the peak and leak down pressure.

  6. Member
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    Mar 2015
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    #6
    Got a chance to hook up the YDS today and found nothing wrong. TPS is at .62 or .63 at idle. Only thing logged is a low fuel pressure, and that was 200 hours ago, so I don't think that's my current problem. I did notice that at WOT, the throttle valve opening is only 62.5 degrees, which seems a little low. TPS is at 3.48 at WOT.

  7. Member
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    #7
    I cant remember off the top of my head WOT throttle numbers. I know minor adjustments in my TPS made pretty big swings in my idle, so maybe try and get that back to nominal instead of riding the upper tolerance. If you have a hot foot, make sure your stop screw is not limiting your stroke, and not letting your motor see WOT.

  8. Member
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    Mar 2015
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    #8
    After reading more about my issue, I'm thinking I may have a sticky reed on the #1 cylinder that's causing it to run rich at idle. Once more air is flowing, it runs fine. Found an old post where someone had the same problems I'm having, and replacing the reeds solved it. Spark plugs even looked identical to mine. Since HPDI's are direct injected, no fuel ever passes through the reeds to keep them clean. I'll probably tear into it when I have time, and after my tournament season is over.

  9. Member
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    Feb 2018
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    #9
    If you remember, could you give an update after you tear into it? I have always wondered if the reeds are something I should change out in my '05 as a preventative measure. Just wondering if it is an easy job, and if that was the cause of your issues.

  10. Member
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    Jul 2020
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    Lake Travis - Spicewood, TX
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    #10
    Same here. Please let me know if it is a "doable" & successful outcome.

    An update from my end -- I am not generally heavy on the throttle, and typically run 3500-4000 rpm (35-40mph), so I also wonder about build up from idle and no hard runs. This weekend I had to put in a long way from my place and made a conscious effort to run in the 5000-5500 rpm range for extended periods. After that, the engine idled considerably better (still at little shaking at neutral/idle, which is think it normal for the HPDI). That said, I have not had a chance to start it cold after those runs, to see if it stumbles when cold. My plan for now is to check the plugs and (assuming they are fouled) run the rest of the Quick silver premium plus, switch to Pennzoil premium plus for an hour or two, then swap in the new plugs. My thought is that this is at least partially due to oil fouling the plugs, and if the claims that PPP will run cleaner is true, it will be helpful. It will be interesting if my #1 is fouled and the others are ok.

  11. Member
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    Jul 2014
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    KALKASKA MICHIGAN
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    #11
    Do a compression test. you may have rings starting to stick and that hard run possibly could have loosened them up. Carbon reeds really help the idle. A decarb would not hurt if you haven't done one. CJ
    2002 X19 200HP OX66 HO Vmax,HPDI lower, it lives, thanks Hydro Tec.

  12. Member
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    #12
    Well I wish I had good news, but unfortunately, I don't. My plan was to figure it out after my final tournament of the year, which was this past weekend. I pre-fished Friday and it ran fine, minus the starting issue. Once I got it running in the morning, it started and ran fine the rest of the day. Saturday morning, I launched and it started pretty easy. Idled out of the no wake zone and took off. Made it maybe 1/4 of a mile and lost power. Motor sounded different too. It would still run, but had a noticeable loss of power. I ran that way for a mile or so, then decided to head back to the ramp. I shut down to idle under a bridge, then when I went to take off again, it would barely get on plane. Put it on the trailer and my partner went and got his boat, so the tournament wasn't a total loss. We lost about 2 hours of fishing time. I haven't had any time to look at anything yet, but my initial guess is that I lost compression on a cylinder. If that's the case, now I have to decide whether to repower or rebuild. On the positive side, at least it happened at the end of the year.

  13. Member
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    #13
    I have been trying to mentally decide on repower or rebuild before it happens to me... I am thinking repower if she's paid off by the time it blows. I would worry about rebuilding a motor with 800+ hours of wear and tear. Sure I could fix the problem and root cause, but would worry about another significant problem coming soon, and so the cycle goes.

  14. Member
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    #14
    From the sounds of things (and inevitably) I will be in the same position at some point. Do any of you know a ballpark cost for a rebuild on these?

  15. Member
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    #15
    About 5k will get it done depending on what issues caused the failure.

  16. Member
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    #16
    Quote Originally Posted by cldtx View Post
    From the sounds of things (and inevitably) I will be in the same position at some point. Do any of you know a ballpark cost for a rebuild on these?
    Hydrotec told me around $6500.

  17. Member
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    #17
    I have a 2006 Stratos with a 2006 HPDI 250 with about 800 hours on it. You guys are scaring me. Mine runs perfectly but who knows? Now I could sell it and put the money toward a new boat. If I wait until it needs major work or re powering, I am out a lot of money and have an 06 boat still. However I truly like that boat. Decisions,decisions!

  18. Member
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    Feb 2018
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    #18
    I'm in the same boat geodebasser.

  19. Member
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    Jul 2020
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    #19
    Same here. Other than the idle issue, it runs fine - 2007 Skeeter ZX225, 2006 225 HPDI with about 500 hours. I spoke with Hydrotech and they quoted me the same $6500. They were helpful and suggested to start with checking for fouled plugs. Unfortunately you see outcomes like the above and the thoughts creep in. At the same time, I feel like I will constantly live with the same fear, regardless of the engine.

  20. Member
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    Apr 2013
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    Yuma, Arizona via Knoxville, TN
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    #20
    Mine did the same, loss of top end, change in exhaust note, and a piston rattle. I lost 50 psi on cylinder #6 on my '08 HPDI 250 Series II, the other 5 have 120 psi. I had put 350 hours on my second powerhead that was replaced under warranty. I'm not rebuilding it again, so I'm repowering to one of the new Mercury Pro XS V8s. I'm dropping the boat off on Monday for the repower.

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