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  1. #16
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    Nov 2003
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    Simi Valley, SoCal
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    Quote Originally Posted by Findre View Post
    I had a no start condition and pulled the ECM plugs and tested a14,A15,A16 and A17 to A23. All 4 pins pairs tested 5.092k.

    Does this mean that they are sharing the same bad resistors? or is the resistance value number wrong in the schematic?.

    I pulled the connector on A15 and it started right up once reconnected ECM plugs. This seems to blow the bad A15 theory if the other I'll inputs are the same.

    Am I dealing with software issues and not hardware issues??
    Are the 5.092k readings to pin A22, the gnd or A23 V+. You should be checking to A23. Those inputs can't share a resistor but you are correct that they should all be the same reading.

    If your voltage is dropping at the ECM while cranking that could be the problem and could be easily tested with the volt meter between ECM gnd (C15, C16 or C24) and V+ (B17 or B18).

    Sorry for the delay...I just bought a boat and was driving 5 hours to get it.


    98 Laveycraft Sebring 20.2 Tunnel 280 "catchin" motor. 90s? It's enough for me!
    96 Cougar 23 MTR twin 300XS's. Currently in an "update controls and interior" mode.

  2. #17
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    Apr 2018
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    It was A23. I hear the injectors and fuel pumps, so I don't think B17 and B18 will help me for a Voltage drop. I did notice the RPMs drop a little with the trim being used. Maybe corrosion at the salve solenoid? Too dang hot down here to mess with it. Ill play around once it cools down.

    BTW I bought a LoadPro so that may help me pin point the problem fast. I should be here in a few days and I'll check back.

  3. #18
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    Trim dropping rpm is around here the wire in the remote rubbing through it’s case. Merc I think 100 and 400 hidden box remote with the metal shift where the wire comes out of the hidden box and up to the switch is where they rub.

    We check them when one comes in as a standard, my personal one has eaten through twice

  4. #19
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    Fin, see if this helps ...


  5. #20
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    Apr 2018
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    I am back. Not resolved yet. Replaced all the parts in the fuel rails just to be sure there was. It issues. New tracker, new fuel diaphragm, new air regulator, new check valve, throttle position sensor was in question, so replaced that also because there was a flat spot throttle. All clean and shiney. Air pressure steady at 80, fuel is 90. On trailer fired right up every time. I put fresh fuel and filters.

    Put boat in water, drove one mile and it died. No start again, pulled SB temps sensor and it fired right up. It ran for a few minutes at idle then died. Back to same no start with temp sensor. New temp sensor x2 also.

    I am back to thinking the PCM is the culprit. When it idles on earmuffs there is a funny miss and surge. I'm sorta at the end of my sanity.

    Any ideas would be great, I've followed everyone's input that has posted. Anything I can do on the bench with PCM to diagnose a problem.? Or should I bite the bullet and find a replacement?

    Thanks again

  6. #21
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    I am back to where I started and am getting back on track. The resolve to start motor was disconnect the SB temp sensor. That will richen the fuel mix, which makes engine start. I think there is a fuel problem, not a PCM problem.

    I rigged up a decent set of liquid filled gauges to see what was going on with fuel and air.

    There was a lot of carbon on the plugs. I used a bore-scope to look at piston tops and they were pretty caked. Put old plugs back in and used 1/2 can of Power Tune misted in the intake and ran on hose.

    Changed plugs, opti fired right up and sounded better while idle.

    I just put it in the water and had a no start condition again, so I hooked up my fuel/air gauges and tried again. I noticed two things. 1) When I connected the air line some liquid sprayed out of the air schrader. 2) the air and fuel pressure were low while engine was cranking for about 10 seconds, still no fire. I put engine on dual batteries and still had a low pressure condition. until......

    I disconnected the SB temp sensor and it fired right up and the pressures when to normal, 90 fuel, 80 air. Reconnected the SB temp sensor. Boat ran flawless how for about 30 minutes a 1000-3500 rpms, pressures max'd at 92-94 fuel and 92-84 air while at 3500 rpms. I wanted to see if there was a fuel problem or restriction. At 3500 not on plane i was at 5.6GPH.
    Got home and boat continues to fire up.
    One note: When I disconnected only the air line, the fuel pressure dropped to about 10 psi with motor off. Is that normal? It started up again without issue, and again the fuel pressure dropped with air pressure while the fuel gauge was still connected when I release the pressure in air line.

    My original theory is that the engine may not be cranking at full speed and not allowing the air pressure to build up in the rails, but with the low fuel pressure based on the air pressure at start, I am not sure my theory is correct. It was cranking long enough and both pressure were low, +-60 psi. It seems that the fuel pressure should be independent to the air pressure and the HP fuel pump should be making fuel pressure unrelated to cranking. When I disconnect the SB temp gauge, it creates a rich setting and that allows the engine to fire even with the pressures being low. I also am considering that the water in the compressed air maybe causing poor fuel when injected into the cyl.
    I think this is a fuel/air problem, not a PCM, and maybe a HPP fuel pump as it doesn't pressurize to the full 90psi before engine starts. I also notice that when it starts with all sensors connected, it sorta starts after about 5 seconds of crank and kinda start rev, not like a BANG start up....a lazy start not a vrooooom. It bang starts when the Temp sensor is disconnected.

    Engine fired up first try this morning, ran for a few minutes but when I tried to restart....nothing (with the temp plugged in). I'm sure if I pull plug on temp, it will fire up.

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