Mercruiser 120 poor starting

Guffer

Cadet
Joined
Nov 1, 2024
Messages
12
Who winterized the boat ? You as usual ? Or some other place ?
Did you have any hard freezing winter weather ? What state was the boat stored in ? Really cold winter in N J. Did you refill your gas tank after the engine repair ?
Yes, I winterised but head was already off. Based in uk, quite a mild winter. 40 l of new fuel but some treatment in existing fuel too. Issue is no fuel getting to carb. Thinking a blocked breather may also be the issue…..
 

Guffer

Cadet
Joined
Nov 1, 2024
Messages
12
I hooked up a fuel line with fresh fuel. She ran for 60-90 seconds and then died. Always felt like it was going to peter out. Does this suggest fuel pump is at fault? Was working before winterisation.

When i try to restart she wont fire at all.

Poured a little fuel down carb throat, wont start.

Notes:
- Found i had air leak at sedimentor so am now replacing fuel line from tank to just before fuel pump
- Still have small drip of fuel on carb intake. Will use some permatex 2 on that as have tried 4-5 times to reseat it
- no block in old fuel line i have connected outboard fuel tank to

Any thoughts?

Many thanks
 

Scott06

Admiral
Joined
Apr 20, 2014
Messages
6,722
I hooked up a fuel line with fresh fuel. She ran for 60-90 seconds and then died. Always felt like it was going to peter out. Does this suggest fuel pump is at fault? Was working before winterisation.

When i try to restart she wont fire at all.

Poured a little fuel down carb throat, wont start.

Notes:
- Found i had air leak at sedimentor so am now replacing fuel line from tank to just before fuel pump
- Still have small drip of fuel on carb intake. Will use some permatex 2 on that as have tried 4-5 times to reseat it
- no block in old fuel line i have connected outboard fuel tank to

Any thoughts?

Many thanks
May be other issues but if you dribble gas down car and I won’t fire then you are missing spark. This assumes the engine has decent compression

a cheap spark gap tester can be helpful to test strength of spark
 

Guffer

Cadet
Joined
Nov 1, 2024
Messages
12
Took fuel intake off the carb and cranked it a few times, so dont think it is the fuel pump. Will test the spark plugs next.
 
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