stalls

racerone

Supreme Mariner
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Dec 28, 2013
Messages
36,032
Year / HP / model #-----------And is this something that happened suddenly ?
 

racerone

Supreme Mariner
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Dec 28, 2013
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Well, start with a compression test.----Do you know if it sat for 15 years ?----Do you have a model number ?---Post all the info you can.
 

boobie

Supreme Mariner
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Nov 5, 2009
Messages
20,826
If this is a 70 hp there is no shift interrupter switch on it.
 

tpenfield

Moderator
Staff member
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Jul 18, 2011
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17,620
motor starts and runs great as soon as I put it gear it stalls

+1 to what the others have said . . . not much to go on to offer advice.

I always get a chuckle out of post where the OP says it 'runs great' and then proceeds to describe a problem that would indicate otherwise. :)
 

willys45

Recruit
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Jan 12, 2017
Messages
4
I forgot to mention that when I have it running on just a hose it starts right up and runs very well. when i put it in the water and shift it into gear which puts a load on it, that is when it shuts down
 

willys45

Recruit
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Jan 12, 2017
Messages
4
I also forgot to mention that I did perform a compression check and all three cyl were within 3 lbs of each other
 

racerone

Supreme Mariner
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Dec 28, 2013
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36,032
It is not running well on a hose, it just sounds like it is to the untrained ear.----It wiil sound wonderful running on 2 of 3 cylinders.---Do you have spark on all 3 leads that will jump a gap of 3/8" or more ??
 

David Young

Chief Petty Officer
Joined
Jul 12, 2015
Messages
485
I forgot to mention that when I have it running on just a hose it starts right up and runs very well. when i put it in the water and shift it into gear which puts a load on it, that is when it shuts down


​Maybe your idle is set too low. When my motor idles on 'muffs', its around 1100-1200 rpm but in the lake it idles around 600-700 rpm. Just something to think about :)
 

Bosunsmate

Admiral
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Apr 7, 2012
Messages
6,129
LOok at your spark plugs too, are they all the same colour and indicating good combustion conditions?
 

oldboat1

Fleet Admiral
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Apr 3, 2002
Messages
9,598
spark, compression and fuel. I would just do it all without trying to outguess things. Check what is easiest first and rule out issues -- 1/2 inch spark with a spark tester, compression test (already found all 3 close to the same, so apparently OK there), drop cylinder test (confirm all three firing). If no issues found, completely disassemble, clean and rebuild carbs. Make sure the fuel supply is fresh and clean with no water before testing with clean carbs, or you may end up having to repeat the cleaning. Permanent tanks in a new-to-you boat are a particular concern for old or contaminated fuel.

If you are over choking/over priming by mistake, you may be running too rich, and stalling -- likewise if there's too much oil mistakenly supplied through a combination of premix and injection. You will see some fouling in those situations -- not fatal to the engine, but won't run well until corrected. And on the flip side, if the pump diaphragm has a tear or hole, the fuel supply won't be sufficient and the motor could stall out when throttling up.

As the motor is new to you, the impeller needs to be replaced. You need to be sure it's not overheating.

So what is the model number? A lot of listers are very familiar with the 70s, and some good pics without the cover on could be useful -- with and without the cover, for that matter.
 
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