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Engine preignition

jimbow77

New member
"I have a 2000 4.3 with mercru

"I have a 2000 4.3 with mercruiser Aplha 1 drive. I can't get it to quit running on when I shut it iff. I have changed the timing,plugs, and checked the choke all which are good. Any suggestions?"
 
"Idle should be no more than 6

"Idle should be no more than 650 rpm in forward gear, fully warmed up, choke off. REduce it if higher.
Are the plugs the correct heat range? Plugs that are too hot can lead to run on.
Normally timing and plugs have nothing to do with run on (because when you shut off the key the ignition is dead).

How is the idle mixture?
If set too rich, this can lead to more run on tendency. Try closing a little until she stumbles.
Is it 2 bbl or 4?

I had a 4.3LX with 4 bl Weber, and it never tried to run on once that I recall.

Rod"
 
It is a 2bbl. I will check the

It is a 2bbl. I will check the idle mixture. I put new plugs in and it ran on the same. Doesn;t seem to be carboned but idle mixture could be the one.
Thx
 
"Jim...
I have a 2005 4.3 wit


"Jim...
I have a 2005 4.3 with mercruiser Aplha 1 drive. Mine runs on as well, sometimes. It seems to do it after a good run of waterskiing or tubing. It idles at about 800 in neutral. I too have to turn down the idle speed, I just haven't turned that screw driver yet. I find that if I wait for about 10 sec. or so in neutral to give the engine a chance to slow down and give the prop a chance to spot spinning, it runs on less frequently.

Wrench"
 
Make sure the throttle cable a

Make sure the throttle cable at the carb is adjusted so there is posotive pressure pushing the carb throttle linkage fully closed and a bit "more pressure". This is commonley over looked and causes the carb to idle higher than normal when returned to neutral. The spring pressure on the carb is not always enough to overcome the throttle cable.
 
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