Hard start after long sitting

K

kurazz

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Jul 31, 2012
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My mercury 50 four stroke (carb model yr 2000) gives me a hard time to start after sitting for couple of weeks or more.

Funny is, after I manage to start engine (sometimes can easily take 30 seconds of cranking with short breaks in between) and leave it running for 10 mins, if I attempt to start engine the following day it fires right away. Basically the longer the sitting time, the harder to start.

The fact that it starts right up on following day I believe eliminates fuel quality (as I use same tank of fuel and stabil additive), and choke, carb setting related issues.

I always make sure I prime engine until primer bulb is hard. In my garage I can also "hear" carbs filling with engine cowl off.

Any ideas?
Thanks
 
MH Hawker

MH Hawker

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Re: Hard start after long sitting

Put some sea foam in the tank.
 
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emckelvy

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Re: Hard start after long sitting

It appears your model has choke shutters; with a solenoid and linkage to operate them, ?Yes?

If so, when you push the key in to choke the motor, does the choke solenoid work & choke shutters move?

If the choke is working, when you start the motor do you keep the choke activated (key pushed in) until the motor starts?

If that's not how yours works, let us know. A model # would be useful info which would help with the troubleshooting.

HTH...........ed
 
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kurazz

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Re: Hard start after long sitting

Correct re shutters and solenoid. However it also has a an electro thermal plunger that opens / closes choke shutters depending on temperature. So during starting I don't need to press in key as choke shutters are already closed and therefore solenoid won't allow for much movement. Within 5 mins plunger pushes choke shutters open as engine warms up. Therefore the solenoid is mostly there to close shutter plates when plunger is warm (hope I explained myself clearly).

Model is 0T0 85XXX. I don't particularly blame the choke as within one day engine would have cooled enough for plunger to collapse and close choke shutters. After one day to 2 days it fires right up. If I let engine sit longer (a week or more) then it just requires more cranking. Sometimes helping with a bit of fast idle on the remote makes it starts quicker but still not "turn key" start.
 
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K

kurazz

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Re: Hard start after long sitting

I have the manual thanks. I checked choke cam angle as seems to be as per spec (+ / - 1mm).
Anything else I can look into?
 
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emckelvy

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Re: Hard start after long sitting

kurazz said:
Sometimes helping with a bit of fast idle on the remote makes it starts quicker but still not "turn key" start.
Click to expand...

Do you use fast idle after sitting for a couple of weeks? You shouldn't expect "turn key" operation on a carbureted outboard, you should always be using some fast-idle-throttle for cold starts. Some motors need more than others.

I don't believe that the "automatic choke" feature acts on the throttle butterflys, so you'd need that extra throttle or she's not gonna start well.

In my very limited experience with EFI motors, seems like they'll fire right up just like a car, without touching anything on the control box other than the ignition switch. But typically a carb'd motor needs a touch more attention to get it fired-off.

Another thing you might check if the above doesn't help is the idle mixture. A little richer on the mixture (while still maintaining a stable idle) will help with cold starting. Also check for vacuum leaks; a split hose can suck air, causing a hard-start condition.

Just a thought.............ed
 
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kurazz

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Re: Hard start after long sitting

Thanks for all feedback.
Agreed that fast idle seems to help but only while cranking to help it get started. It will not start with fast idle lever is pulled out. What I mean is, I generally pull fast idle a little while cranking. Then when engine shows signs of starting I push it back all the way down. If I leave it pulled up just a little it will probably wont ever start (or takes even longer). Not sure if this is normal.
Once it starts I also have to let it rev at normal idle for a few seconds till it settles. If I pull fast idle lever to rev it and help with warm up immediately after it starts, it just chokes and shuts off.
Not sure if any of these symptoms help explain the cause of hard starting in the first place?.
 
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