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Best way to start a 150HP Carburated O/B

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docecg

New member
I realize this has been beat to death but I cannot get my o/b to start consistently. I have been advised several ways but this motor just has a mind of its own. Appreciate any advice. Have a 2005 Mercury Carb'ed 2.5 150. My carbs are clean and the motor functions but every-time I go to start it is always different. Thanks, DocECG

Having two Verado's has spoiled me. Hope I dont need three...
 
Outline the starting procedure you are using now.----Perhaps we can give you some tips then.----------------A motor like that in good condition will start right up if the correct procedure is used.
 
My carbs are clean...
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Meaning what? Recent clean and rebuild? Buying fresh fuel from a reliable branded high volume vendor and using stabilizer will always ensure easy starts. Is the fuel tank clean?
 
A slow cranking starter motor will lead to hard to start condition.----------Possible causes are bad starter / wrong starter ( they all look the same ) / bad wiring / bad battery.
 
When was the last time the "crank case check valve" was replaced? If this service part is not working correctly it will make for hard starts. It's job is to pressurize the remote oil tank only while the engine is running and to relieve the pressure in the oil tank after the engine is shut down. If the valve is clogged it will leave the oil tank pressurized and will fill the carbs with a heavy oil ratio leading to hard starts. You cannot clean this part. It lists for around $16.00.

http://www.marineengine.com/newparts/part_details.php?pnum=MER21-878105++1&ptype=&Engine=&Model=
 
Thanks to all your advice. In the morning is when it is a bear to start. I prime my motor, then hold in the key and finally it will turn over. It then just bumps. So I crank again still the same thing. I was told to prime, then turn key press in for 5 to 6 seconds and it will start. If a motor keeps cranking is that due to a lack of gas? It will start just never the same way...Just frustrating.. Thanks Doc
 
Do you hear the primer / enricher " click " when you push in the key?---Do you hold the key pushed in while cranking ?-------Do you advance the throttle while cranking as well ?----If you apply the correct procedure then the motor will start right up
 
docecg said:
Thanks to all your advice. In the morning is when it is a bear to start. I prime my motor, then hold in the key and finally it will turn over. It then just bumps. So I crank again still the same thing. I was told to prime, then turn key press in for 5 to 6 seconds and it will start. If a motor keeps cranking is that due to a lack of gas? It will start just never the same way...Just frustrating.. Thanks Doc
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The part I mentioned will cause hard starts during the first start of the day.
 
I turn the key push it in for 5 seconds then turn it over. I do not back off the key. I do not advance the throttle. Thanks, ECG
 
Docecg--------Your starting procedure needs some refinement.---------------Find out how to advance the warm-up throttle ( keeps it in nuetral ) on your control box.-------And do you hear a " click " when you push in the key ??-----------When you answer the questions then folks can help you !!
 
Well, no-one has mentioned the position of the engine. I think its important,(well to me it is, gas don't run uphill). Any way here's my starting procedure for my '95 Mag 3. I squeeze the bulb til its tight before leaving for the landing. ( 20 min ride) In the water, I lower the motor til it's level. I turn the switch on, press in the key and count to 6 or so. I bump the motor, press in the key again for another 5-6 seconds. I raise the fast idle control and turn the key and start it. ( In colder weather, I need to increase the times to 8-10 seconds ) Works for me. Hope it helps anyone who has a starting problem...BF
 
Does the enrichment system continue to add fuel if the key is left pushed in when starting or does it enrich just once every time the key is pushed in???? Is this possibly a 4 cylinder 2+2 ???? The 2+2 starts and runs on only 2 cylinders below 1800 RPM.
 
It's a V-6...the enrichment solenoid supplies fuel as long as the key is pushed inward per my merc. manual.
 
Most folks are used to our modern cars where all you do is turn the key and roar down the road.----------The starting of older motors means that the operator should take the time to learn what each and every step does for the starting process.-----On more than one occasion folks that had trouble starting their motor have said.----" Thank you for taking the time to teach, I have learned something "
 
Check the position of your primer bulb, it acts as a one-way valve and should stand up, arrow pointing to the sky, so get it as close to your motor as possible, then check the quick connect ( if you have one ) they can suck air. Next would be the square lift pumps diaphragms and check valves, if these were not upgraded to the new nylon type then do so. You need fuel in the fuel line for the choke to work anyway. Some models have a thermo valve located on the stb head, if you have check the piping and function of the valve.
 
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