Old Mercury 50 HP Help

Well I have my last couple of parts trickling in from boats.net for the Merc, hope to take a whack at getting it running either this weekend or next week. Right now I am working on some fiberglass repair on the bottom of the McKee, should keep me busy for a bit!

-Svence
 
She runs...well sorta. Got everything bolted on, carb leaks fixed, fuel line fixed, starter on, gased her up and she ran. Was shocked to be honest as it fired up the first crank of the key. Now the problem is she won't stay running. I think it may be a fuel pump issue as if I keep priming the bulb it stays running, if not I get about 15 seconds before she dies out on me. What I don't understand is the fuel pump on these carbs, how the hell do the work? Where do they get their pulse from to pump? I am used to seeing either an electric pump or a line from the crankcase pulsing the diaphrams, any ideas?

-Svence
 

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Pulse comes from the front half, where the carb bolts to the intake, no special lines. There should be a special base gasket that has corresponding holes to the ones in the intake and carb that all line up. I know it to be this way on some.
 
Great, unbolting the carbs again!!!! So that little hole pulses the diaphrams in the pump to fill the bowl, got it. I am finishing up the fiberglass work today and should be able to focus on the engine later on this week so I can really troubleshoot the problem. Thanks for the help.

-Svence
 
Got some time yesterday to look at it. It is definitely something with the fuel delivery as I can just continuously pump the ball and it will stay running. Now before I pull both carbs is there anyway to test the fuel pumps to see which (if only one...) is bad? The carbs I have include the fuel pump so I can't get a pressure gauge between the pump and the bowl and I don't know how else to test just one pump at a time because it's just a T before the two pumps. Any ideas?

-Svence
 
I don't have a clue on how to test pressure or volume on that one. Maybe you could let her run out of fuel and then see which bowl has the least amount of fuel by removing the bolt that pinches the float bowl to the carb housing. (The dry one will only drip for a few seconds) Or better yet mix you some 2-stroke blended fuel in a squirt can and give the motor a little squirt just as it starts to run rough. (right down the throat of the carb(s).) The motor should pick up and indicate the one that is going dry. I was going to say it would be OK to keep it running on carb spray but no lubrication there. If I remember right my old 50 would run on 2 cylinders when the other 2 weren't 100%. But the other 2 were flooding out, needle stuck. Did you go into the fuel pumps when you went into the carbs?
 
The carbs were rebuilt prior to me buying the boat (no idea what that means though...) and looked like they were cleaned with new gaskets so I am assuming (I know, I know) the pumps were replaced. When I did tear down the one pump to find a small leak, and fixed it, the diaphrams looked good and clean with no tears/holes. I know I am going to have to tear them off the block and take them apart, just trying to minimize having to do both if I can!

Anyway, might try to bowl drain trick. You also got me thinking, might wait until it stalls out then pull the fuel line from one, plug it and pump, switch and repeat. That might let me see which needs more, IF it's just one!

-Svence

-Svence
 
If I were you I'd change out both of them regardless.A little more work this season could save you from doing it again next season.
 
Well just got the gaskets pulled and I think I found the problem...The gaskets between the carb and block were upside down, the pulse hole was completely blocked. The gaskets were installed before I got the motor so I never even thought about it. Off to get two new ones tomorrow. Also going to change out the fuel pump diaphragms as I have two of them sitting here now. Hope this gets it all straightened out.

-Svence
 
X2 What Lathehand wrote. I would go thru the carbs and double check evrything after finding the gaskets upside down. That was your A-HA moment right there.
 
Gaskets and diaphrams replaced and she pumps fuel! Everything is up and running, just need to tweak the idle. Hoping to splash her tonight. Thanks for all the help.

-Svence
 
You putting it on the McKee Craft? Good to hear she pumps and runs.
The one time I had carb issues with mine it was flooding at the boat ramp in Homasassa at the beginning of a fishin trip. I managed to take one of the carbs off, free up the needle and put her back together. I mean end wrenches, crescent wrench and a screwdriver. Went 40 miles that day. Never had to go back in the carbs and it didn't even take a gasket set.
 
Yup. Picked up an 82 McKee 14 with it. She's taking a splash this weekend, first time in the water with her, hope for the best!

-Svence
 
And so it continues...

Ran her this evening and can't get past 3/4 throttle or she dies out. Up to 3/4 everything seems okay but once I bump it past there it stalls out. Even if I just throw it WOT and back she fades and then comes back to life. Any thoughts? There is no high speed adjustment on the carbs so i don't know where to go from here.

Here's where I stand...
Brand new tank, fuel line, primer bulb and fuel pumps cleaned so I don't think there is a shortage of fuel. Also it won't even try WOT as if it has gas and then runs out, it just dies as soon as I move it up past 3/4.

-Svence
 
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Anyone know what the compression numbers should be on this? Just did it and they seem low, but even. Top 80, 84, 85, 80 Bottom. Could just be the compression tester (autozone loaner) but I have no idea what it should be.

-Svence
 
Just going to keep this thread updated....

Well stator is toast and I am down two coils (might be firing might not, both tested ok, not okay, okay, not okay). Think that may be why I am not getting any power under load.

-Svence
 
That really sucks. I hoped you had her all ironed out. What do the plugs look like? They should be pretty wet if the fuel issue was solved. Drenched if the ignition is fouling up. Check and recheck the grounds for the coils. I think they ground to the mounting plate on that motor. If the stator is junk, I would start there and also test the trigger thouroughly because you will have the flywheel off anyway.
 
Stator and four coils with plug wires on order. Trigger tested out fine based on the Mercury manual. The plugs were definitely getting fuel, plenty wet when I pulled for compression test. I am just glad I am finding things wrong that I can fix and not just hitting a dead end.....although it would be nice if there were things to find wrong ;)

-Svence
 
Your compression seems a little low but thats not that terrable as long as each cylinder is within 10% .
sounds like to me your on the right track with the stator.Change that out and you'll have a nice set up.that;ll bre hard to beat
 
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