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  1. #11
    Join Date
    Dec 2016
    Location
    Louisville, KY
    Posts
    137

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    Hot days only? Could be vapor lock. When you're not in motion are you venting the engine compartment?


    Sent from my iPhone using Tapatalk
    '92 Comp ts6m - 5.8 PCM Pro Boss Carb
    '02 Launch SS - 5.7 Indmar Assualt TBI

  2. #12
    Join Date
    Apr 2012
    Location
    Tacoma, Wa
    Posts
    861

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    It's fuel injected.
    2003 Supra Launch 22SSV
    1986 Ski Natique 2001

  3. #13
    Join Date
    Apr 2012
    Location
    Tacoma, Wa
    Posts
    861

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    The inside of the cap says "vented" or something like that so I would assume that is normal. I would check the fuel pressure under running conditions prior to change out components. Things can get really confusing on symptoms when you start swapping parts.
    2003 Supra Launch 22SSV
    1986 Ski Natique 2001

  4. #14
    Join Date
    Apr 2015
    Posts
    15

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    [QUOTE=Zkdk3000;129765]Hot days only? Could be vapor lock. When you're not in motion are you venting the engine compartment?

    The boat restarts with ease every time, and the coughing/spitting doesn't kill the engine. From what I understand, that sounds unlikely to be vapor lock. It runs great under 2000 rpm.

  5. #15
    Join Date
    Apr 2015
    Posts
    15

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    Quote Originally Posted by CornRickey View Post
    The inside of the cap says "vented" or something like that so I would assume that is normal. I would check the fuel pressure under running conditions prior to change out components. Things can get really confusing on symptoms when you start swapping parts.
    Ok, maybe I'll do that tonight. I haven't done it before, but I'm guessing you buy a fuel pressure gauge and hook it up somewhere between the pump and the throttle body?

    Another update. The return fuel line had two micro sized holes from the hose bubbling at two points that were leaking small amounts of gas. Hence why my hand got gas on it while tracing the lines. Replacing both the sender and return lines. I don't see how this would create any of the issues I have been having, so I'm not really considering that as the problem. Thankful nothing bad has happened with leaking fuel!
    Last edited by tbs156; 08-03-2017 at 07:52 PM.

  6. #16
    Join Date
    Apr 2012
    Location
    Tacoma, Wa
    Posts
    861

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    Install the gauge in the Schrader valve on the fuel rail on the port side. If it is tbi you'll have to do some research. With your floor up I would confirm the one way check valve it's functioning properly. It is mounted to the return line between the hose and the tank fitting. It screws into the 90 degree brass fitting on the tank and has a barbed end for the return hose.
    2003 Supra Launch 22SSV
    1986 Ski Natique 2001

  7. #17
    Join Date
    Dec 2009
    Posts
    107

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    Could possibly be the ignition control module? If it gets too hot it will not function properly. But you replaced the distributor, maybe you also replaced the ignition control module sitting in the distributor?

  8. #18
    Join Date
    Apr 2015
    Posts
    15

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    Got an update! Could use some help on these final steps.

    Talking to a mechanic buddy and he recommended unplugging the tan wire w/blue stripe. It's some type of temperature sender that could be cutting fuel. Well, turns out it was already unplugged, or there are two of them. We found one already unplugged on the bow/starboard side of the engine. Didn't get a chance to find where it might plug back in to, will look tonight.

    However, we saw another tan wire sticking off the aft of the engine in the center at the top, turns out that goes to the temp gauge in some way. WELL! Unplugging that wire, bam boat ran like a dream, no coughing, sputtering nothing for several minutes straight. During this time of good operations the temp gauge stayed at "0" (makes sense). We have now concluded something is electronically cutting fuel to the engine above 2000 rpm (after being warm for 30 min). I'm not sure if this is considered 'limp mode'. But it is all adding up.

    Didn't want to risk overheating the engine by unplugging temp gauge for too long, so for now its plugged back in. But now, wondering what diagnosis this is? Something appears to be sending a false signal to the boat that it is overheating or something. The temp gauge itself seems to work ok and boat runs at 160 on the dot throughout the "bad" operations.

    Some semi-unrelate side notes:

    Going to double check impeller because it has been 2 years anyways this weekend.

    Also, we replaced the fuel lines intake/return and the throttle position sensor at the same time. The boat ran terribly at idle and super rich (gas pooling behind the boat). We had installed a new fuel pickup tube, cut that at an angle at the bottom, retightened connections, filled lines with gas before plugging them back in, and put the old TPS back in. One of those things fixed that issue, but certainly made me nervous!
    Last edited by tbs156; 08-08-2017 at 05:48 PM.

  9. #19
    Join Date
    Apr 2015
    Posts
    15

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    Quote Originally Posted by roosm View Post
    Could possibly be the ignition control module? If it gets too hot it will not function properly. But you replaced the distributor, maybe you also replaced the ignition control module sitting in the distributor?
    Did not replace the ignition control module, only the cap and rotor.

  10. #20
    Join Date
    Dec 2009
    Posts
    107

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    Quote Originally Posted by tbs156 View Post
    Did not replace the ignition control module, only the cap and rotor.
    Mine died, more suddenly than yours. If memory serves me right. First time the engine did some coughing and then died, once cooled down it started up, quickly died and remained dead.
    I read a bit on the issue and found that the IGM can break from corrosion or heat and that it can start working erratically before it fails. In my case I got no spark.
    The idea is basically that the IGM will get a pulse from the magnet on the rotor every time the rotor lines up to fire on a cylinder. This will tell the ECM to operate the Igniction Coil.

    Might be a long shot, but you could possibly try to remove the IGM. Clean it from old heatsink-paste and corrossion, apply new heatsink-paste and re-mount it. If the issue is that it gets hot new heat sink paste might keep it cool enough.
    Less corrosion on the ground point would also develop less heat. I am pretty sure mine died from corroded ground points since they looked bad.

    I am however no expert on the matter, more talking from personal experience and what I have read elsewhere.
    One thing that is for sure is that mine ran better after the new IGM. With old EGM I would always do crank-crank-crank-fire. Never an issue starting, but it just took a few revolutions. After the new ignition module it fired probably 10-times as fast. It was basically instantaneously from turning the key.

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