Fuel/Air Mixture

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Fuel/Air Mixture

Poor idle, hesitation.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Fuel/Air Mixture

Instead of beating around the bush with probably not related questions, why don't you just tell us what your problem is, and what engine you have.
 

dawson515

Seaman
Joined
Mar 24, 2009
Messages
61
Re: Fuel/Air Mixture

Sure, sorry. 89 2.3 OMC. Just replaced the shift cable. Boat runs fine on muffs but when it is in the water and it is around 2500 rpms there is a small engine knock. I had a problem earlier with the boat not idling right so I adjusted the fuel/air mixture screws and I wanted to make sure that that did not cause the problem.
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,548
Re: Fuel/Air Mixture

Adjusting the air fuel mixture screws is for idle only.

What is your timing and dwell set at?
 

180shabah

Rear Admiral
Joined
Mar 26, 2005
Messages
4,995
Re: Fuel/Air Mixture

fuel? fuel filters? timing? vacuum leak??

possible need of carb rebuild after 21 years????
 

dawson515

Seaman
Joined
Mar 24, 2009
Messages
61
Re: Fuel/Air Mixture

I am going to do a compression check on all 4 cyl this evening just to make sure that there are no issues there. I am giong to add some octane booster to the fuel and then go from there.
 

ENSIGN

Lieutenant Junior Grade
Joined
Jun 21, 2009
Messages
1,179
Re: Fuel/Air Mixture

If the knock you are hearing is a connecting rod or a piston slap noise your carb has nothing to do with it.Check the oil and the oil pressure.The problem might be just old age.
 

dawson515

Seaman
Joined
Mar 24, 2009
Messages
61
Re: Fuel/Air Mixture

YES, It was a five hour job that I dedicated one evening to. Boat runs perfect now.
 

180shabah

Rear Admiral
Joined
Mar 26, 2005
Messages
4,995
Re: Fuel/Air Mixture

Glad you got her all back together, did find the root cause for the head gasket failure?
 

dawson515

Seaman
Joined
Mar 24, 2009
Messages
61
Re: Fuel/Air Mixture

I am sure it was because I ran it hot. I bought the boat knowing it had an overheating problem. I checked the thermostat and it was bad so I changed it out. I took the boat to the lake and i forgot to tighten the hose that come from the water pump to the thermostat housing, so no water was getting to the engine. The boat got to 200 degrees before I realized what happened. I fixed the hose and started the boat again to try to get water to the engine to cool it off, well, it did not work and the boat got hotter, well, I ended up finding an impeller blade stuck in the thermostat housing that was blocking the water passage to the motor. So that fixed the overheating and then I noticed that the boat smoke and there was a knocking coming from the engine. Did a compression check and cyl 3 was low. I pulled the engine apart replaced the gasket and now she is running strong. Believe me, if I can fix diagnose the problem and fix it just about anyone can.
 
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