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Smarty pants, I really could use your help! 350 Mag trouble SOLVED?? MAJOR UPDATE

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    frenchshipfrenchship Member Posts: 1,079 ✭✭✭
    I would say that Al is your best shoot. You probably exhausted all the Infos and help you can get this forum.
    Good luck
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    WildboatingWildboating Member Posts: 957 ✭✭✭
    Loboring at 60% of 3600 rpm
    2003 Rinker 342 Fiesta Vee, 350 Mag MPI, Bravo 3 2.20:1 w/ 22p 4 x4 props

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    aero3113aero3113 Member Posts: 8,869 ✭✭✭✭✭
    I think he had this issue with the first motor before it was replaced also. 
    2008 330EC
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    Dude_HimselfDude_Himself Member Posts: 596 ✭✭✭
    What's the compression on the good motor?
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    Handymans342Handymans342 Member Posts: 10,375 ✭✭✭✭✭
    Come on Man!
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    212rowboat212rowboat Member Posts: 2,591 ✭✭✭✭✭
    it's a major PITA to check.... i still bet, after all this time, you are off on your cam/crank timing.  one or two teeth off will do everything you have described.  it's toooooo easy to do.  advance it at the crank, and your valves close early- increasing the dynamic compression... retard it at the crank and the valves close late, decreasing compression... the injectors sync off of the CPS, which only knows when/where to fire based off of the camshaft's position... the spark is driven off the cams nose- releasing every other revolution- the computer, as smart as it is, is at the mercy of things being aligned.  

    to check it you must find TDC on the compression stroke on #1, and observe the dots.  pray there are dots present on both cogs (the cam and the crank).. otherwise, it gets tricky fast with degreeing wheels/cards.   your fuel injected- there is nothing to be gained by advancing or retarding at the crank/cam relationship.  

    slop in your chain will do it too.  not as much as you describe, but to a degree. 

    all of this will impact your vacuum signal as well, which if i recall correctly, you had the weak engine dropping signal.  

    now this is just a stupid question... but... 

    do you draw power off of both engines? both have functional alternators? how about power steering pumps? both of them or just one? if one-n-one, is the weak engine providing both functions?  anything belt driven is a parasite of power- it's easy to steal it from the crank.  a bad alternator, for instance, can stall an engine at idle (or cause awful squealing)... i'm curious if the weak engine is carrying the load, which will not only limit it's production, but allow the other one to widen the RPM delta by being less burdened.  
    click here for faults (BEEP) list
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    Dude_HimselfDude_Himself Member Posts: 596 ✭✭✭
    From memory the starboard engine provides steering hydraulics via the power steering pump.
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    Black_DiamondBlack_Diamond Member Posts: 5,439 ✭✭✭✭✭
    Look at the fuel line coming from the tank where is passes thru the firewall.  Mine was so tight around the corner is was certainly restricting flow.  

    Past owner of a 2003 342FV
    PC BYC, Holland, MI
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    WildboatingWildboating Member Posts: 957 ✭✭✭
    Ok, thanks guys for the advice.  I had to step away for a moment.  To frustrated Friday night.   

    So so did anyone watch the video I posted?  Those who can help, what do you make of this.  Skip 50 seconds in the crank the volume up on whatever you are listening with.  Watch, you will hear as I hit around 3600 rpm the motor falls and the fuel pressure starts acting up.  
    2003 Rinker 342 Fiesta Vee, 350 Mag MPI, Bravo 3 2.20:1 w/ 22p 4 x4 props

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    WildboatingWildboating Member Posts: 957 ✭✭✭
    Here is the video again.  https://m.youtube.com/watch?v=mWNu8drY5LA&feature=youtu.be
    2003 Rinker 342 Fiesta Vee, 350 Mag MPI, Bravo 3 2.20:1 w/ 22p 4 x4 props

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    WildboatingWildboating Member Posts: 957 ✭✭✭
    what can cause these fluctuations?  You hear the motor falling off  rhythm .   

    2003 Rinker 342 Fiesta Vee, 350 Mag MPI, Bravo 3 2.20:1 w/ 22p 4 x4 props

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    Handymans342Handymans342 Member Posts: 10,375 ✭✭✭✭✭
    Do the same test with a 5 gallon jug with the line hooked up to the new lift pump you just installed IF that is a good pump. 
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    Handymans342Handymans342 Member Posts: 10,375 ✭✭✭✭✭
    @Wildboating please tell me if when the engine was running was everything hooked up as normal?
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    Handymans342Handymans342 Member Posts: 10,375 ✭✭✭✭✭
    Your missing something easy
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    WildboatingWildboating Member Posts: 957 ✭✭✭
    This is all hooked up, we overlooked this before but we now see and hear it.  Did you hear it in the video??? Engine sounds like cylinders are cutting out.   I will retry al's suggestion.  I think Based on the audio cylinders are misfiring at 3600. 
    2003 Rinker 342 Fiesta Vee, 350 Mag MPI, Bravo 3 2.20:1 w/ 22p 4 x4 props

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    WildboatingWildboating Member Posts: 957 ✭✭✭
    @Handymans342

    cant be that easy.  I have been through several shops in Cleveland.   I wonder if I have an electrical issue that manifest at around 3600 rpm. 
    2003 Rinker 342 Fiesta Vee, 350 Mag MPI, Bravo 3 2.20:1 w/ 22p 4 x4 props

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    WildboatingWildboating Member Posts: 957 ✭✭✭
    What can cause those low spikes in pressure?  Are Cylinders cutting out and affecting vacuum causing these spikes?  Voltage fluctuations? High speed pump failing?   Grrr.  One day someday, it will be fixed. 
    2003 Rinker 342 Fiesta Vee, 350 Mag MPI, Bravo 3 2.20:1 w/ 22p 4 x4 props

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    Handymans342Handymans342 Member Posts: 10,375 ✭✭✭✭✭
    Well it appears that you haven't done what Al or I have suggested
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    Black_DiamondBlack_Diamond Member Posts: 5,439 ✭✭✭✭✭
    Have you swapped the coil yet? 

    Past owner of a 2003 342FV
    PC BYC, Holland, MI
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    Black_DiamondBlack_Diamond Member Posts: 5,439 ✭✭✭✭✭
    That 180psi seems high for a compression  number to me. 

    Past owner of a 2003 342FV
    PC BYC, Holland, MI
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    WildboatingWildboating Member Posts: 957 ✭✭✭
    @Black_Diamond

    i swapped the coil.  Unfortunately it didn't help. 
    2003 Rinker 342 Fiesta Vee, 350 Mag MPI, Bravo 3 2.20:1 w/ 22p 4 x4 props

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    Black_DiamondBlack_Diamond Member Posts: 5,439 ✭✭✭✭✭
    Have you tried using a pump separate from the engine ones to pull fuel from the tank?  Hook up to the line going to the fuel filter on the firewall. 

    Past owner of a 2003 342FV
    PC BYC, Holland, MI
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    WildboatingWildboating Member Posts: 957 ✭✭✭
    @Alswagg. Are you saying fuel pressure would not spike like it does with a cylinder cutting out.  This would not affect the fuel pressure regulator to this point?   I am tempted to purchase a new cool fuel module.  
    2003 Rinker 342 Fiesta Vee, 350 Mag MPI, Bravo 3 2.20:1 w/ 22p 4 x4 props

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    Black_DiamondBlack_Diamond Member Posts: 5,439 ✭✭✭✭✭
    FYI there is a 'new' gen 2 cool fuel module from Mercury. 

    Past owner of a 2003 342FV
    PC BYC, Holland, MI
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    WildboatingWildboating Member Posts: 957 ✭✭✭
    New one??   Do you have a part number?
    2003 Rinker 342 Fiesta Vee, 350 Mag MPI, Bravo 3 2.20:1 w/ 22p 4 x4 props

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    Dude_HimselfDude_Himself Member Posts: 596 ✭✭✭
    At this point, with all you've done/tried, it seems that it should be running tip-top shape. Since you have a good engine and a bad engine, I'd start looking to see what's different and why. I might start by checking the actual mechanicals - stroke depth, compression, timing (both valve and ignition), etc. If that doesn't pan out then I'd swap one complete system - ignition or fuel - to see what happens. I don't think a bad sterndrive would be asymptomatic - but it wouldn't be too much effort to swap them as a last ditch effort.

    Might be helpful to list out all the steps you've taken for us that are following.

    I'm with Alswagg - the quickest way might be to pull it and throw it on an engine dyno - the problem will manifest there quickly. You can't hide from the dyno.
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    WildboatingWildboating Member Posts: 957 ✭✭✭
    edited August 2017
    Swapped drives out.  

    Brand new Mercruiser 350 long block, problem existed before and after

    New injectors

    Swapped coils

    New Dist cap, wires, plugs

    Swapped TMAP

    Swapped IAC

    New Boost Pump

    Ran From 5 gallon tank, (redoing this test per Al's instructions)

    Compression test  ( cranked until stopped building pressure, not 4 strokes   All cylinders near 205)

    Fuel Test, No water in Water fuel seperator, 7% ethonol.  

    Scoped Exhaust for obstructsions all the way to the gimbal boot with camera.  Not blockage, exhaust flappers are intact and in use.


    I need to think about what else.   This shoud give you a good idea though.   Did you watch the fuel pressure video i posted?   @Dude_Himself


    Swapped ecm



    Post edited by Wildboating on
    2003 Rinker 342 Fiesta Vee, 350 Mag MPI, Bravo 3 2.20:1 w/ 22p 4 x4 props

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    aero3113aero3113 Member Posts: 8,869 ✭✭✭✭✭
    Could it be something as simple as a corroded ground?
    2008 330EC
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    reneechris14reneechris14 Member Posts: 3,134 ✭✭✭✭✭
    Should swap the hole distributor, I still think it's a blockage on exhaust just my 2 cents, I'm no pro.
    2005 Rinker FV342  Pawcatuck river,Ct
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    JasonAJasonA Member Posts: 40 ✭✭
    I am fighting a very similar issue with my 8.2 ECT. WOT is not near max RPM (it can surge just like yours does in the video). After changing both fuel pumps for about 30 minutes boat ran like a champ (4500rpm vs 3800rpm). Then the issue showed its head again. Mechanic is coming Wednesday to change plugs and wires and do a compression test.

    I am getting misfire codes on my VV4 and nothing else. I have changed both the crank and cam sensors so far. Have you tried to swap PCM's yet?
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