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    4.3 Mercruiser Power problem!

    Well, tune up, fuel delivery, compression, are the first things that come to mind Have you inspected anything aside from runability?
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    Help understanding vacuum test

    15 to me indicates a sound engine. As long as there is no variation of more than 1 inch and it returns to 15 after a throttle open/closed fairly quickly I'd say you're set. Of course the ultimate idle vacuum is approx 17 with little to no variation but I would have no hesitation to run full...
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    Mercruiser 5.7 ?

    Depends on crankshaft or prop horsepower. Horsepower is a great number, something most folks can relate to, however the number a boat operator should be interested is torque. That's what gets a boat up, out of the water and on step. Horsepower keeps the boat (planing hull) up and maneuverable...
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    early 70's Mercruiser 165hp inline 6 w/ MC-1 drive not going into gear (sometimes)

    Wow, can't imagine a dealership having to rig an mcm. Outboards, yes but an i/o package would be a tall order for a boat and engine manufacturer to trust proper install. I guess today, in America at least we get stuff from various boat manufacturers already rigged (sterndrive/inboard/v drive)...
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    early 70's Mercruiser 165hp inline 6 w/ MC-1 drive not going into gear (sometimes)

    Gotta agree with jimmy on this. I have no idea what mercury did in the 60's to 70's. You make it sound like dealers not manufacturers rigged the boats? Like sea ray, bayliner, slick craft, etc...just left it to the seller to rig. Can't imagine arbitrarily attaching decals to blank drives...
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    1978 5.7l pre-alpha with alpha gen 1 drive over heating

    Pretty important to replace the base assy and impeller housing on early style alpha/mc 1 drives and pressure test as well. Base gasket failure is quite common on those style drives. As mentioned a 143 t stat is recommended
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    DTC 113: IAT voltage high ( please help )

    IAT = intake air temp. Without eyes on the engine or any other info at that can't say as to if your engine has a separate iat sensor or not. MAP is manifold absolute pressure, MAT is manifold air temp. My guess is there may be a sensor on or near the flame arrestor I know it's a different...
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    89 centry palimino with a 3.7 mercruser charging issue.

    Yep, most likely fried the regulator. Part is nla, might get lucky on ebay but you'd be buying used. Others here run the 3.7 and can help with troubleshooting but they may suggest the alternator upgrade....
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    Fuel pressure

    Iirc mercs standard mechanical fuel pressure for carbureted engines is 3-7 psi steady pressure under load. If you're too high you run the risk of overpowering the needle/seat causing flooding issues. Correction for too much pressure is to add a thicker gasket between the pump and block
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    4.3 V6 leaks wet oil sump

    Ime the most common leak for crankcase oil on a vortec 4.3 is the fwd corners for the oil pan/timing cover. Looks like some decent paint flaking off the pan, is there heavy corrosion elsewhere on the motor? Best option for locating leak is to clean all residue from outside, top off the...
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    4.3 merc . spring starup

    No amount of searching the net will change a zero compression cylinder, need to investigate your engine, not computer
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    4.3 merc . spring starup

    Um, but I thought #4 has zero, not 125?
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    2003 Merc 5.0 MPI no start, intermittent spark

    What ignition system do you have?
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    Maintenance intervals

    I can take a dump in a box and give you a guarantee.... Point is, when I head to parts room I'm getting a quality part, after all it's not my money, ymmv
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    Hard starting

    You work on boats?
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    Hard starting

    If I had eyes on secondary bowl removed could confirm. Worry about top end performance after you get low speed performance dialed in
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    Hard starting

    Would say most if not all are fouled. Buy new plugs but get engine/carb dialed in with old plugs. Can't see your issue being due to fouled plugs, seems more your issue is rich causing fouled plugs
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    Hard starting

    Especially at idle/low rpm. Don't forget faulty power valve gasket can/does cause rich conditons at low rpm. One backfire on a holley equipped engine means 99.9% chance failure of power valve, ymmv Once carb is set and motor is operating sound my next inspection would be a plug burn/inspection
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    What is this guard around the valve spring?

    Is an a frame. Mann made product, solid and easily road transportable with one person capability of blocking on stands
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    What is this guard around the valve spring?

    This is boat I refer to....
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