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    95 4.3lx alpha one mercruiser cooling system question

    Yes, there is a weep hole in the circ pump housing. Yes it will leak water if the shaft seal is failing. Rarely does a freshwater run raw water cooled circ pump fail. If yours isnt leaking out the weep hole odds are against it having failed. Your issue is too little raw water supply from the...
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    Hose leak at trim pump oil reservoir

    The hose ends are a flared fitting, there are no seals between the hose ends and the pump/manifold at the bottom of the transom assy. I've never seen/heard of a kit to replace any non existent seals. The only fix is to replace faulty fittings on the hose end/trimp pump or the entire hose assy...
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    Mercruiser 6.2 - 90amp fuse

    Test the fuse for continuity, if no continuity or very high and the contacts look questionable, replace the fuse
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    5.0 Gxi-ce 270-r misfires cyl 4&7 at full throttle

    Kv meter on the plug wires will show if the spark plug(s) are getting proper voltage, especially at speed/load Otherwise, I'd be suspect of fuel supply as others have mentioned
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    Mercruiser 6.2 - 90amp fuse

    Main purpose of the 90 amp fuse is to protect the alternator and battery from damage in case someone connects the battery cables backwards. It's cheaper to replace the fuse than an alternator/battery The 50 amp breaker protects the rest of the engine circuits from damage and has been present on...
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    4.3 mercrusier wires go to??

    Mercruiser manufactured more than just a tks model 4.3 liter engine in 2007. They also produced efi models during that period. It's possible they purchased wire harnesses from another company and modified them to fit their engines. Or they made the harnesses and used a template/base type of...
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    No spark or fuel pump

    Is the engine efi? A model/serial number will help a lot WAG based on provided info is the main power really if the engine is indeed efi
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    4.3 mercrusier wires go to??

    Trim limit switch/wiring is not associated with the engine wiring harness. Wire colors for the limit switch are purple and blue and are part of the trim pump wiring harness I'm guessing it's possible someone installed separate wiring for the trim guage if the brown and black wires pictures...
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    Lean Popping on Accleration

    The ecm controls injector pulse width based on engine load and rpm. Fuel pressure is a fixed value the ecm assumes is constant and has been programmed to control pulse width based on the assumption. Some ecms do measure fuel pressure, unsure if volvo uses a fuel pressure sensor though. My guess...
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    4.3 mercrusier wires go to??

    If the orange/pink wire is indeed part of the tks system it could have been removed because a component of the system failed and instead of repairing it some one abated it. I'm not near any manuals atm but may get to it later today if I have time. If the tks system is operational you'll note a...
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    4.3 mercrusier wires go to??

    Photo shows tks on the flame arrestor information decal. If it's original it should have a serial number for the engine and a model number/signifier. Would be fairly confident the two black appearing wires are ground that have been cut, stripped and twisted together. Definition not oem. Mercury...
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    2007 Volvo Penta 5.0gxi - no compression in # 4 cylinder

    1. Yes, I've seen the very same 2. Depends on how much damage is in the cylinder and how much/if it needs to be bored. If it's more than bigger rings can compensate then the other five cylinders will need bored as well At the very least you need a valve job. As far as piston/cylinder damage...
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    Volvo Penta 5.7 no spark

    Simply unplugging the map sensor on a sound engine harness/sensor/ecm system should not cause a no spark/run issue. Could be there's something faulty with the harness connection/5 volt reference circuit associated with the map sensor There's mention early on in the thread about an audible alarm...
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    help help help overheating Mecrusier

    Agree with others about checking water supply, flow/volume at the thermostat housing and checking for blockages/back flushing the water supply line/cooler(s). Yes your engine has a water pump mounted on it, known as a circulating pump. They fail much much less than a sea water pump. Easiest way...
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    Intermittent Alarm Beep - Mercruiser 5.0 V8 MPI

    Can't recall ever seeing a gen 2 impeller that cooked before. Based on your previous posted temps with an IR temp sensor that is testament to Mercury's upgrade from the alpha one style pump
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    Intermittent Alarm Beep - Mercruiser 5.0 V8 MPI

    Thinking more on it'd be best to disconnect the oil pressure switch and see if the problem goes away/continues
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    Intermittent Alarm Beep - Mercruiser 5.0 V8 MPI

    No Based on the info provided I'd be suspect of a short somewhere, possibly a faulty key switch. Might also be a chafed wire(s) at/near the helm
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    Mercruiser 383 Mag Stroker MPFI Bogs Over 3000 rpm

    Those spark plugs are toast, fouled with excess deposits. Reviewing the pics posted I'd guess this is a saltwater boat with raw water cooling? Based on the patina and other aspects I'd guess the distributor cap needs replaced at a minimum. Doesn't appear that the risers/manifolds have ever been...
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    5.7 MPI Misfires Under Load

    Nothing abnormal looking to me. The voltages follow the sensor movements pretty close and are within the 5 volt range. With no faults present there's no reason to suspect an issue with the 5 volt ref from the ecm. With a graphing/recording of data you look for consistency (which you have) for...
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    Mercruiser 383 Mag Stroker MPFI Bogs Over 3000 rpm

    37 psi is close to spec but should be more around 42 psi steady at all rpms/load. Based on the fuel supply troubleshooting it's possible the high pressure pump is faulty. Only other test I can think of is a fuel supply vacuum test or running on a remote fuel tank. A faulty in gear/neutral...
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