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43 mercruiser weber 4bbl carb problems

Y

ycart0

Member
"First of all thanks to everyo

"First of all thanks to everyone with the help with water getting in the spark plug hole. I think , I hope I have that problem solved.

New issue wouldn't you know.

After running the afternoon on fathers day the engine just died at an idle. It was getting late so I put it up for the night. 2 days later when i had the chance to work on it I had to adjust the air/fuel mixture screws and idle screw to get it to run. Then I thought that I should go ahead a change the fuel / water filter. After doing that I had to re-adjust again. The next day we took the boat out. When starting from a dead stop pressing the throttle all the way down the engine wanted to bog. but you can run at wot for a few minutes. then let up and after about 30 secs accel and it won't bog.

I tried adjusting the 2 air/ mixture screws. With both screws being 1 1/4 turns out. engine spits and sputter thru the carb. Right now I think each side is 2 1/2 turns out. When i first set this setting it seemed to pick up ok. I added 1 pint of seafoam to my gas. today it did ok but still hesitates on load. And it still bogs when first put in the water.

Another issue is when the engine is warmed up you can turn it off. wait 30 secs. then crank it and it cranks ok. But if you wait five minutes you have to cranks the engine for about 4 secs. let off of the starter. then crank again and most of the time it starts.

This carb has been rebuilt. I think the problem is in the 2 air / fuel mixture screws.
Can you guys give me your opinion and also explain the way the air fuel mixture screws work. I know if the screws are out to far the boat won't run right and if they are in to far it won't run right. But I don't know how to tell when I have the proper setting?
Thanks for the help sorry this post is so long but I figure the more info you have the better your able to advise me on how to fix my problem>>"
 
Do you know if the secondaries

Do you know if the secondaries are opening up? Is the choke pulloff diaphragm working? Idle mixture screws are adjusted w/a warm engine. Adjust idle speed to specs. Start with the screws backed out 1-1/2 turns. Turn clockwise and mixture will become lean. Counter clockwise enrichens the mixture. Slowly turn in untill the engine stumbles and then turn other direction until it stumbles agian. Turn the screw back half the distance between the two stumble points. Do the same for each screw. Slowly.
 
"[b]"This carb has been re

""This carb has been rebuilt."

Ayuh,... Sounds like it picked up somemore Crap,+ needs rebuilding again..."
 
"What is the secondaries?

O

"What is the secondaries?

Once engine is warm choke stays open all the time? is this right or should it be closing when trying to start every time?

With the idle mixture screw 1 1/2 times out the carb has a whistle? Some times when I go wot it trys backfiring. When adjusting the idle/ mixiture screw where should the actual idle screw be turned to? Cause I probably have that all wrong also. Thanks guy, bondo, and everyone else

Tracy"
 
By reading your comments about

By reading your comments about the carb I must agree w/Bondo. Have a professional rebuild the carb and set it up. Four barrel carbs are more complex than two barrels.
 
"Thanks for the adive on getti

"Thanks for the adive on getting a professional to rebuild but I don't have the xtra money to pay him / her...


But could you please answer my questions reguarding if the choke should be on open when the engine is warmed up, What does the whistle mean?
Could you give examples how the engine would act if the idle mixture screws were out too much? and how the engine would act if the idle mixture screws were in too much? Especially when accelerating fast to wot? Thanks Guy and everyone else for your help..."
 
"Tracy
Idle mixture screws m

"Tracy
Idle mixture screws mean just that, they only work on idle, not high speed or intermediate speed. the whistle is coming from some other source, usually a vacuum leak.
The choke should be open when the engine is warmed up. If you have no money then kinda live with what you have. You can throw money at an engine all you want but sometimes hiring a mechanic is cheaper.
Bert"
 
screws out too far; fuel/air m

screws out too far; fuel/air mixture is too rich and engine will run rough and belch black sooty smoke and also foul the plugs.

screws in too far; fuel/air mixture is too lean and engine will backfire some and run rough.

Screws should be adjusted between running rough w/screws out and screws in.

secondaries are the two smaller butterflies that should open near full throttle. The sound of the carb will change when they are open.
 
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