4.3 Merc Tune up

Jsmith4

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Oct 3, 2017
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Hello everyone. New to the site and first time posting here. I live in Michigan and own 1993 K18 Kayot with the 4.3L Mercruiser Alpha One with Thunderbolt IV ignition. Purchased this boat last summer with zero maintenance records but it's fairly clean. Only thing I've done is changed the starter to a marine grade (when it died first time out lol) and put new tires on the trailer. That starter fact leaves me a little weary on the general upkeep and maintenance if any was done previously to the engine.

I've taken her out about 12 times total and only for about an hour of run time in each session, so managed to go through one tank of gas over the last 2 seasons. I always use additives and add stabilizers at end of the year, along with anti-freeze and fogging oil. She's already down the road and in the barn for the winter.

Now this year she's had some trouble re-starting after doing about 20 minutes around the lake and getting nice and hot. I've noticed I've had better luck restarting when I have the neutral throttle barely bumped forward. I keep thinking it could be vapor locked but I keep forgetting to bring the starter fluid to test this theory. But then again I didn't have this problem before, so I really need to do some general maintenance.

I'm searching for part numbers on:

Plugs
Wires
Cap
Rotor
Impeller
Gear lube the outdrive - how many ounces of gear lube does this take and what are the replacement o rings/gaskets for drain plugs
Change engine oil
Fuel pump
Fuel filter or water separator?

If anyone can chime in with a service manual or the correct part numbers for these that would be much appreciated. I've heard good things about Quicksilver replacement parts. I've also seen bundles of tune up parts like plugs wires cap and rotor from Quicksilver for around 90.00$. Just want to make sure I get the right parts.

Thanks again! I'd post a picture but apparently im not authorized...
 
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Bondo

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Plugs
Wires
Cap
Rotor
Impeller
Gear lube the outdrive - how many ounces of gear lube does this take and what are the replacement o rings/gaskets for drain plugs
Change engine oil
Fuel pump
Fuel filter or water separator?

Ayuh,.... Welcome Aboard,....

Spark plugs I run are AC Delco, MR43T,...

I'd ohm the wires, as they're probably just fine,....

Cap, 'n rotor, I donno the numbers, but ya oughta be able to figure that out, as the 4.3l is the only 6 cylinder Merc used in the '90s,...

Gear lube, ya need 2 quarts of high quality syn-oil, I use Mobil 1, 75W-90,...

Motor oil, I use Shell, Rotella T, 15W-50,...

Why change the fuel pump, unless it's failed,..??

The fuel filters I use are Napa, 3225, or the slightly shorter Napa 3226,....
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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iboats sells all the stuff you need as well.
 

Jsmith4

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Oct 3, 2017
Messages
9
Thanks for the great info. I ordered the Clymer Mercruiser Stern drive shop manual along with 6 MR43T plugs. Also picked up 2 quarts of the Mercury Precision Lubricants SAE 90 GEAR Lube.

Looking for the correct kit to do the water impeller but there are a few to choose from on iboats catalog.

I'm having a hard time figuring out if I have a water separator or not, I did some searching and I'm thinking not.. the boat is down the road in storage so I can't easily peak. But my searching on the forums leads me to believe not, only a fuel filter is present.

Anyone know why I'm not authorized to post pictures?

Thanks again
J
 

Scott06

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Three posts before you can post pictures, looks like your still at two
 

QBhoy

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Likely problem is the auto choke. In my experience. I know I rattle on about this. But it's common place with most of the engines like this in my experience. Local Merc dealer used to insist on this after a few years
 

Jsmith4

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Oct 3, 2017
Messages
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QBhoy would you please elaborate on the auto choke, do you believe it is set improperly?
 
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Jsmith4

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No Title

Pulled a spark plug and it has the NGK BR6FS - they will all be coming out for the AC MR43T plugs. Also checked my VIN and it is a 1993, so that would explain why I cant find the fuel water seperator. Guess I'll find a kit on ebay to add that in, anyone have a recommended product? I took some pictures but having trouble loading them.
 

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Jsmith4

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Is a fuel water separator needed? What are the benefits? If I add this will this also act or can I delete my current fuel filter?

If it is highly recommended, would you get the filter with the drainable bowl at the bottom?
 
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Bondo

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Is a fuel water separator needed? What are the benefits? If I add this will this also act or can I delete my current fuel filter?

If it is highly recommended, would you get the filter with the drainable bowl at the bottom?

Ayuh,... The pump mounted filter, 'n the carb filter don't stop water,....

The canister filter is a great diagnostic tool for runability issues, to find water,..

Get a canister type filter that uses the Merc thread pattern, without the bottom drain,...
 

Jsmith4

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Oct 3, 2017
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Ok. So I'm looking at separators and most of the Sierra models I've found say this

"Not recommended for use with diesel fuel or with 1992 Gen II 4.3L & 4.3LX engines with electric fuel pumps using in-line filter #35-80531T"

Is that my in-line filter? I have an electric pump with a small almost automotive like filter down stream of it.
 
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achris

More fish than mountain goat
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May 19, 2004
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The 92/93 V6s had a strange filter, that's NLA... You need to remove the in-line canister and replace it with a section of tube (used on later models) and fit a standard 'spin on' water sep filter....

Chris.........
 

achris

More fish than mountain goat
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Messages
27,468
.... I ordered the Clymer Mercruiser Stern drive shop manual ...

Unfortunately they are a complete waste of time and effort. You need the genuine Merc factory manuals (one for engine and one for drive)... You should be able to get them from any Merc dealer, or an online dealer.

Chris............
 

Jsmith4

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Oct 3, 2017
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Unfortunately they are a complete waste of time and effort. You need the genuine Merc factory manuals (one for engine and one for drive)... You should be able to get them from any Merc dealer, or an online dealer.

Chris............

lol wonderful..


So this is what I'm thinking for Fuel water separator... Sierra PN 18-7853-1 filter base
Delete my old canister filter... no good
Mount the Sierra in its place if possible, might be easier to just mount it on the back of the storage bin/lower seat thats directly aft of the engine.
Get rid of that fuel line between filter and Electric Fuel Pump and just use a barb fitting on the end of the Electric Fuel Pump, haven't checked the threads or if a fitting is out there...

So yeah I'd be adding like 3 barbed fittings (2 off separator and 1 off pump) to my system total and some lengths of Fuel Grade Flexible hose. Should be pretty easy...

Got access to my old photobucket :thumb:

Thanks for the great info guys!

 
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Jsmith4

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Oct 3, 2017
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My new spark plug wires came. I measured the resistance from an old plug wire at 13.1 vs. new plug wire with same length at 10.3

Thoughts?
 
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achris

More fish than mountain goat
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My new spark plug wires came. I measured the resistance from an old plug wire at 13.1 vs. new plug wire with same length at 10.3

Thoughts?

Nothing serious. Still well usable.
 
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