75hp Mercury 2stroke 2008 Starting problem

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304

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Anybody help with problem starting above engine , last couple of months it has taken longer each time to start . When it does it’s fine . I noticed that the ignition buzzer also takes time to come on once key is turned to first position, . Since I’ve had the outboard the buzzer always sounds when going slowly but scrolling the smart craft info shows all ok ? Apart from checking spark plugs firing not sure what’s next step ? Any ideas ? Thanks
 
304 said:
what do they do ?
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They let the fuel mixture pass from the crankcase to the cylinder inlet port.

The problem i had with mine(I'm not suggesting it's your problem) was..
In a 2-stroke engine, it's essential to maintain a seal in the crankcase to ensure the correct pressure for operation.
 
billskip said:
They let the fuel mixture pass from the crankcase to the cylinder inlet port.

The problem i had with mine(I'm not suggesting it's your problem) was..
In a 2-stroke engine, it's essential to maintain a seal in the crankcase to ensure the correct pressure for operation.
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Main bearing seals can do that too. But I can’t see that making cold starts hard if it starts ok warm. I think a sensor for the fuel injection is more likely. All of the other possible causes would significantly affect performance. Though it is incredibly hard to diagnose such things remotely.
 
Chiara’s slave said:
Main bearing seals can do that too. But I can’t see that making cold starts hard if it starts ok warm. I think a sensor for the fuel injection is more likely. All of the other possible causes would significantly affect performance. Though it is incredibly hard to diagnose such things remotely.
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Reed valve being brittle can make it run lean making it hard to start. Some compression loss would do the same. As you say hard to diagnose without seeing it
 
Chiara’s slave said:
But I can’t see that making cold starts hard if it starts ok warm
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Well actually I can assure you from my own personal experience this was the problem i had with my engine.

Only affected cold start, didn't affect warm or restart, I stripped engine down initially looking for reed valve damage, but theory didn't allow this to be possible.

My theory was when engine warm metal expansion tightened up the seals, changed the seals and engine became a totally different monster,

For a period of time initial starting was to remove plugs, squirt small amount of fuel into pots, and fire it up, engine would start and run fine for the rest of the day, this slowly became more of a nuisance, so winter i stripped it and replaced seals, Reed valves were fine.
 
Ok. I’m pretty experienced with 2 strokes, but mostly motorcycles. I have a reed valve 2 stroke bike still. Reed valves, minor point of order, are between the inlet and the crankcase. A seal failure allows air/mixture back out. In this case just air, as it’s direct injection. Theoretically it ought then to run rich. But 2 strokes can be cantankerous beasts, so chaos theory rules.
 
So collective wisdom back to original poster. It could be lots of things.

P.s. this is incredibly unhelpful but i never liked the triple cylinder mid range mercury two strokes.
 
Chiara’s slave said:
A seal failure allows air/mixture back out.
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Back out where? As the piston comes down it pressurises the specific crankcase area seald to that piston, lf it's multi piston
the crankcase fuel pressure can leak (..faulty seals...) across to the adjacent crankcase section and be exhausted ...
As was happening to mine, faulty/worn
seals between crankcase chambers.
 
billskip said:
Back out where? As the piston comes down it pressurises the specific crankcase area seald to that piston, lf it's multi piston
the crankcase fuel pressure can leak (..faulty seals...) across to the adjacent crankcase section and be exhausted ...
As was happening to mine, faulty/worn
seals between crankcase chambers.
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The outer seals are usually the first. But if your centre seal on a twin fails, the air will move from one case to the other, less case pressure,
less cylinder charging, less power. I guess the symptoms are similar to loss of compression. On bikes, an outer seal can draw gear oil in, you can lay a trail of smoke like a steam train.
 
potentillaCO32 said:
So collective wisdom back to original poster. It could be lots of things.

P.s. this is incredibly unhelpful but i never liked the triple cylinder mid range mercury two strokes.
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You may be right about Mercury, but I have a bit of a fetish for other triples. Kawasaki, Laverda, MV Agusta, Triumph, Suzuki, have all made great triples.
 
Chiara’s slave said:
You may be right about Mercury, but I have a bit of a fetish for other triples. Kawasaki, Laverda, MV Agusta, Triumph, Suzuki, have all made great triples.
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My favourite mercury 2 stroke was the v6 blackmax 150 i had. Silky smooth, fantastic power and easily tuneable.
I did have a suzuki x7 2 stroke but i preferred 4 stroke bikes
 
Many thanks to all for your input , I have taken plugs out and they were blackened , did a compression test few months ago and they all were equal over 150psi , Would diagnostics pick up on sensor for fuel injection. ? The engine runs lovely ,accelerates smoothly, plenty of power ,no smoke ,idles fine ,if slow trolling the buzzer goes off after few minutes to check engine but shows all ok
 
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