Carb to MPI problem 2011 Merc 4.3

[kbryant]

Hello
Does anyone have a video link on showing how to rebuild a carburetor.
2011 Tahoe Q5i 4.3 Mercusier Alpha 1. The engine hesitates on lid.

MOD EDIT: started off as carb but post 15 makes it a MPI

 

[Scott Danforth]

Both cliffs and Mike's have how to info

 

[kbryant]

Both cliffs and Mike's have how to info

Hi Scott
What does that mean?

 

[Scott06]

Hi Scott
What does that mean?

cliffs high performance and mikes carb parts are both excellent parts and tech resources.
mikes has a you tube channel with how to vids

Cliffs High Performance Quadrajets – Quadrajet Rebuild Kits, Cabruretor Parts, Quadrajet Rebuilding, Quadrajet Parts, Bushing Kits, Carb Tuning

Mike's Carburetor Parts

www.carburetor-parts.com

 

[Scott Danforth]

Hi Scott
What does that mean?

It means that you should not trust any generic video from YouTube. Too many people just want to post things that are not correct.

Both Cliffs high performance and Mikes Carburetors are vetted and correct information for those that did not grow up rebuilding carbs and turning wrenches

Most likely your issue is a clogged accelerator pump circuit or a bad accelerator pump plunger

 

[kbryant]

Hi Scott,
I hope rebuilding the carb will help.
It idle fine and when you give it some gas it runs rough and then smooths out. I’ve changed Fuel filter, new plugs and wires, new fuel pickup value. So I think it’s the carb issue.

 

[Scott Danforth]

That transition from idle to what ever RPM you finish at is where the accelerator pump adds extra fuel. If the pump circuit is plugged, it will stumble like you indicate

 

[kbryant]

That transition from idle to what ever RPM you finish at is where the accelerator pump adds extra fuel. If the pump circuit is plugged, it will stumble like you indicate

So I’m a rookie at this but I can figure things out. The pump circuit is part of the carb? I know stupid question. Do you think a rebuild on the carb could help? Everything else is good. All gauges etc….
Thank you for taking time to help me out. I really appreciate it.

 

[Scott Danforth]

Yes, a rebuild will help. The accelerator pump circuit is within the carb

 

[kbryant]

Yes, a rebuild will help. The accelerator pump circuit is within the carb

Do you think putting on a new one or rebuilding one is better?

 

[Bondo]

Do you think putting on a new one or rebuilding one is better?

Ayuh,..... Carbs rarely wear out, they just get crud in 'em,..... Clean fuel is a Must,.....

A carb kit is 20 bucks or so,..... a new carb is a few hundred bucks,....

 

[Scott06]

Do you think putting on a new one or rebuilding one is better?

Definitely rebuild the one you have. The main part is to make sure you are getting the passages clean. I use a harbor freight ultrasonic cleaner works nice on the rebuilds i have done with it. Thats is whee most carb rebuilds fallshort , need to get passages clean. From your description either the accelerator pump circuit or transition circuit is clogged or non functional .

check the contents of your fuel filter. If you have fuel system contamination it will just pollute the fresh rebuild

muscle car solutions and uncle tonys garage have some good carb videos on set up and operational theiry/ how they work

 

[kbryant]

Definitely rebuild the one you have. The main part is to make sure you are getting the passages clean. I use a harbor freight ultrasonic cleaner works nice on the rebuilds i have done with it. Thats is whee most carb rebuilds fallshort , need to get passages clean. From your description either the accelerator pump circuit or transition circuit is clogged or non functional .

check the contents of your fuel filter. If you have fuel system contamination it will just pollute the fresh rebuild

muscle car solutions and uncle tonys garage have some good carb videos on set up and operational theiry/ how they work

Thank you thank you
I will order a rebuild kit and give it a try.

 

[Scott Danforth]

Do you think putting on a new one or rebuilding one is better?

I have only ever come across 1 carb out of about 4-500 that I have gone thru that needed replacing vs a cleaning and new gaskets. your choice, buy a new OEM carb (not the chinese amazon crap, however a good Mercarb or edelbrock for about $500, or spend the afternoon with 2 beers, a carb kit and a bit of carb cleaner. for about $50 total. the rebuild always is a better job on your wallet.

 

[kbryant]

Ok
I like beer so that sounds like a better idea. The only thing is I don’t know how the hell to pull carb off this 4.3 Merc. I can’t find a video about that. Picture attached. Where do I begin

 

[Scott06]

Ok
I like beer so that sounds like a better idea. The only thing is I don’t know how the hell to pull carb off this 4.3 Merc. I can’t find a video about that. Picture attached. Where do I begin

That is not a carburetor. You have an mpi engine.

when was the last time cap and rotor were changed ? Common fail point on these engines is the crab cap.

 

[Scott Danforth]

Per the picture, not a carb, however as Scott pointed out MPI injection

 

[kbryant]

Per the picture, not a carb, however as Scott pointed out MPI injection

That is not a carburetor. You have an mpi engine.

when was the last time cap and rotor were changed ? Common fail point on these engines is the crab cap.

No kidding. So it’s injectors? This sounds like not a good thing. Could it be the cap causing the rough running at higher rpm’s?

 

[Scott06]

No kidding. So it’s injectors? This sounds like not a good thing. Could it be the cap causing the rough running at higher rpm’s?

No MPI is very good. 220 hp on your engine vs the 190 hp carbed model.

yes the cap is a common fail point for misfires. Certainly could be other things but if you dont know when it was changed would be a good thing to rule out.

 

[ROY WILLIAMS]

Ok
I like beer so that sounds like a better idea. The only thing is I don’t know how the hell to pull carb off this 4.3 Merc. I can’t find a video about that. Picture attached. Where do I begin

the carb is corroded !!!!!!!!!!! new the carb ......
I was my carb 1978 , the carb is the plastic bag on top of the port ... sprayed it of the penetrating oil ...
the carb is the alcohol gasoline . take it off of the carb top part .. then throttle body spray TB spray ... and did the cloth and a small brush .. the spray bottle did the plastic tube ...orifice port ..