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    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Mark, Chris1956 is unfortunately not correct, and neither was I. Thanks for the detailed photo - it helps to identify which engine you have. You have an engine with the 464 mark I mentioned on the flywheel. The screw on the bottom left in the photo of the spark arm is the throttle pickup. If...
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    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Oh, and the specs in the factory service manual are for good gas because these engines have 9.5:1 pistons. MTBE is banned so ethanol-free "recreational gas" has no oxygenate in it. Your carb engine will run lean on E10 unless you re-jet the carbs and you will have to retard the timing to keep it...
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    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    If the OP's engine is '85 production it's a 75, not an 85, and it has the old switchbox. Does not have a timing advance/retard module. Whether it's a 800, 850, 80 or 75 they all use the same 67 cube powerhead. Depending on the serial number break, if it's got the 464 mark on the flywheel, then...
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    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Because that screw adjusts the timing, not the throttle opening. You need to verify that the sync between the timing and throttles is right. The timing needs to be at 8 deg BTDC before it opens the throttles or the engine will bog out and hesitate as soon as it goes off the idle circuit in the...
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    Merc Outboard - 2 Year Old Engine Failure, 5 Year Extended Warranty Denied

    Really? So we have factory certified techs that are certified to do what? Replace assemblies? Anybody can do that. The purpose of factory certified techs is to provide full service and repair for what the manufacturer sells. You can darn well know that if the powerhead had a warrantable internal...
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    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    If you don't have a service manual for the engine, now would be a good time to get one. The linkage you point out moves the trigger plate for the ignition timing and this all has to be synchronized to advance the timing and open the throttles in the right sequence. Yes, you absolutely need a...
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    Merc Outboard - 2 Year Old Engine Failure, 5 Year Extended Warranty Denied

    The thing is, it doesn't make any difference what fogging oil was sprayed into where, you have to prove it. Mercury will stick to the water ingestion thing no matter what as far as any warranty coverage on the powerhead. I know from working on that 90 with a 2.1L last year that Mercury will not...
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    Merc Outboard - 2 Year Old Engine Failure, 5 Year Extended Warranty Denied

    Mercury Marine is not gonna cover it, we already know that. I hope the OP got the old engine back. It can be fixed with a new or used piston and rod and some gaskets in a day. Sold online he could recover just about all the cost of his replacement powerhead. If the dealer claims it had to go...
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    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Now is a good time to do a full sync and ignition timing. The idle on those is with the throttle plates fully closed. All the idle stop does is adjust the base ignition timing. If all the linkages are properly set it will increase speed off idle, initially, by advancing the timing before the...
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    Merc Outboard - 2 Year Old Engine Failure, 5 Year Extended Warranty Denied

    It all depends on the person doing it. Some people tend to get carried away with the fogging deal. I've seen some people run a whole can thru a two-stroke outboard before. If you get one of those fogging the jugs on your four-stroke - if a little is good a lot must be better - yeah, you can lock...
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    Merc Outboard - 2 Year Old Engine Failure, 5 Year Extended Warranty Denied

    Actually, Mercury does say to remove the plugs and spray 1 ounce of fogging oil in the plug holes (5 seconds in each one), then turn the engine two complete revolutions before re-installing the plugs. IMO this doesn't do a dang thing except convince you to buy a $20 can of their Quicksilver...
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    Merc Outboard - 2 Year Old Engine Failure, 5 Year Extended Warranty Denied

    Not as remote as you think. I saw this happen to a 90 (same powerhead) while it was running. However, it's fairly apparent. The float switch in the FSM won't shut off the low pressure pump. And if you pull the sparks plugs it'll blow raw gas out the plug hole. As I said before, it was most...
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    Merc Outboard - 2 Year Old Engine Failure, 5 Year Extended Warranty Denied

    Doesn't take much to bend a rod in one of these engines. Yeah, the piston skirts hits the crank counterweights and that's what makes the "ticking" noise. But as long as nothing breaks off and comes flying thru the block the engine is rebuildable. As it is, if the OP buys the powerhead from...
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    First boat buyer questions

    The 14ft Polar Kraft is a practical fishing boat. The Hydrasport 180 is a bass racer. Unless you're into bass racing (tournament bass fishing) and getting an education on how much boats really cost to own and operate, the 14ft Polar Kraft will make a better choice for a first time boater. The...
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    Merc Outboard - 2 Year Old Engine Failure, 5 Year Extended Warranty Denied

    New and revolutionary? Mercury's design is all borrowed automotive technology with single overhead cams (instead of DOHC) to save weight and two valves per cylinder with a super light duty bottom end and slipper-skirt automotive style pistons. Their machining processes are so poor, and the block...
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    Merc Outboard - 2 Year Old Engine Failure, 5 Year Extended Warranty Denied

    That's understandable. But at the same time realize a bent rod is not Mercury's fault (short of an injector failure) - something hydraulic locked it to cause that. So really, this gets down to the dealership. You haven't asked why if it's got a bent rod they don't just replace the rod and...
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    Merc Outboard - 2 Year Old Engine Failure, 5 Year Extended Warranty Denied

    Yes, they can be tested. But typically if the dealer has an engine that's flooding they're going to throw in a whole new set of injectors and you're gonna get a $2,700 bill. And they're gonna tell you water got in the fuel and that's what caused it. Or sometimes they'll blame it on E10 gas, even...
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    Merc Outboard - 2 Year Old Engine Failure, 5 Year Extended Warranty Denied

    Seriously, if it's not under warranty (and I doubt it is gonna be covered because Mercury doesn't care), why not buy an aftermarket rebuilt powerhead for it? I've seen the 2.1L powerheads for in the $2,500 range as long as you have a good core that doesn't have a hole in the block or a broken...
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    Merc Outboard - 2 Year Old Engine Failure, 5 Year Extended Warranty Denied

    Yes, the 2.1L four-cylinder. The system logs hard faults for cylinder misfire, fuel pump output, idle air control, the warning horn, ignition, tach, temp, steering override (if equipped) and injector pulse. It also provides outputs for various sensors for diagnostic purposes if you have a...
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    Merc Outboard - 2 Year Old Engine Failure, 5 Year Extended Warranty Denied

    It's doubtful there's any stored codes for it. The ECU on your Mercury engine is pretty basic, it is not near as sophisticated as modern automotive systems. It will log a hard sensor fault, but not something like a bent rod. If you have not been in contact with the shop that did the...
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