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2008 4.3l tks

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psychedelic_sunshine

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Been having issues with a flatness when accelerating causing the engine to bog down and die. Started after my dad rebuilt the carb two or so years ago, we thought it was just improper tuning as it only happened when in the water under load. The issue has persisted we've have tried tuning it while out on the water (my dad has, I'm just the accelerator controller so I'm not positive on everything he's adjusted) I ended up doing some research and suspected the accelerator pump so we took apart the accelerator pump today and I noticed the plunger, spring, and basically whole thing look vastly different from photos and vids online so my dad found the original one and I compared it and they look incredibly different. The new one is way harder to push down the spring on it and it stops and feels stuck almost immediately without even the spring compressing all the way whereas the old one compress down smoothly. I want to preface this by saying I am a complete novice when it comes to carburetors so I am just wanting to know if them being so different would make that much of a difference that it would cause issues that couldn't be fixed by tuning. Intuitively I feel like if they are this different, that no matter how we tune it we won't reach the proper set up. For now I put the old one back in and we will go give it a shot when we can but until then I'd like to know. Feel free to correct me if I am wrong and if I am then I will have more questions. lol Please help with any advice, I really want to help my dad get his boat running smoothly he hasn't been able to enjoy a stress free day of fishing in so long and I just want to help him get this fixed. If I am missing vital info let me know and I will do my best to provide as much as I can. Pictures included of the two pump assembly differences, bottom showing the depth the spring can be compressed on each of them.

Not sure if the photo is showing up but if it isn't here is a link to it.
https://imgur.com/a/mSHefb0
 
Get the engine serial number so we can look at parts diagrams.

Also, was the repair kit a Mercruiser kit or aftermarket? Would you have the kit part number?
 
A bog when accerating is typically due to accelerater pump issues so your on the right track.

99% of the time, a new Acc pump would look/be identical to original with possible color differences. The umbreller/wiper diameter should be the exact same as original with the exception of the original shinking due to aging/wear
 
Been having issues with a flatness when accelerating causing the engine to bog down and die
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Can understand bogging on acceleration but dying is something else. The accel pump not giving a full stroke on quick acceleration will cause a bog but the main jets should keep enough fuel flowing to keep it moving up in RPM

I'm leaning toward the original carb cleaning didn't get all the fuel channels fully cleaned out.

How does it run when cold? There should be a louder hissing sound until the TKS module closes
 
The one on the left looking at the bottoms looks way to big to me. I agree with kghost above. The new rubber piece should only be slightly larger in diameter than the old one bc of the old one being worn. Also I always try to use a vacuum gauge when adjusting carburetors. You want the most and the smoothest vacuum at idle. Sometimes I do that by ear just listening to how it sounds and runs but I am old school.

Let us know how the old accelerator pump works if it removed the flat spot.
 
Roadking57 said:
The one on the left looking at the bottoms looks way to big to me. I agree with kghost above. The new rubber piece should only be slightly larger in diameter than the old one bc of the old one being worn. Also I always try to use a vacuum gauge when adjusting carburetors. You want the most and the smoothest vacuum at idle. Sometimes I do that by ear just listening to how it sounds and runs but I am old school.

Let us know how the old accelerator pump works if it removed the flat spot.
Click to expand...
TKS carbs have a metal cover on the idle mixture screw. So unless they cut it off they cannot adjust...
The last one I worked on, I cut the cap off and put a slot in the head of the screw. Made final air/fuel adjustments very easy
 
I apologize, I assumed they were "tuning" the carb out on the water. Yes most 4BBL Quadrajets had those metal sleeves covering the mixture screws. They are hardend too making them not drillable to pull out. I usually turn the butterfly plate over against a lead block and chiseled them
out.
Don't TKS mean Turn Key Start? Not sure about that, will have to research it.
 
Roadking57 said:
I apologize, I assumed they were "tuning" the carb out on the water. Yes most 4BBL Quadrajets had those metal sleeves covering the mixture screws. They are hardend too making them not drillable to pull out. I usually turn the butterfly plate over against a lead block and chiseled them
out.
Don't TKS mean Turn Key Start? Not sure about that, will have to research it.
Click to expand...
It is a 2 BBL carb
It has a electric solenoid type enrichment for cold start idle control. It is basically an electro-mechanical choke that allows extra fuel through a passage for about 6 minutes or so (a real POS).
The carbs have NO mechanical or elctric choke components that are familiar

There are two versions, one for 4 cylinders and one for V6 & V8
 
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AllDodge said:
Can understand bogging on acceleration but dying is something else. The accel pump not giving a full stroke on quick acceleration will cause a bog but the main jets should keep enough fuel flowing to keep it moving up in RPM

I'm leaning toward the original carb cleaning didn't get all the fuel channels fully cleaned out.

How does it run when cold? There should be a louder hissing sound until the TKS module closes
Click to expand...
Agreed carb didn’t get clean.

To the OP Need to use an ultrasonic cleaner and stop it again

I think the kits from mikes carbs have are really god quality . Also would look at plunger for power valve that it operates freely
 
kghost said:
Get the engine serial number so we can look at parts diagrams.

Also, was the repair kit a Mercruiser kit or aftermarket? Would you have the kit part number?
Click to expand...
this is the boat info not sure which one is the serial number i asked my dad and he sent me his info document with all of these numbers. Also update we haven't tried it on water yet but today he messaged me saying this "I just got everything back together measured checked everything. I’m doing it in the backyard right now and it’s still stalling" From what he told me I was under the impression that it only happened when we were out on the water thats why he needed me to come with him so he could tune it while I drove so I may have been wrong about the under load part. Anyways not sure where to go from here with it, I was really hoping it was the accelerator pump so now I am at a loss.
 

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I have found most but not all of the companies (ebay)selling the replacement 2bbl carbs work perfectly out of the box.Avoid the pretty ones painted Black, they painted the insides too. Most under $135
 
I have concluded carbs may not be the strong suit for the OP's dad...Bt's recommendation may be the fastest route to getting his back on the water to enjoy it...
 
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