Mercarb running rich

"I rebuilt a 2bbl mercarb off

"I rebuilt a 2bbl mercarb off a 1987 seaswirl 4.3 sterndrive and since then it bogs and pops at wot. I can back off the throttle and run the lake all day.
I finally realized it is running rich. My lake altitudes are between 5600-7600 feet above sea level. I realized the jets are 165 which is sea level jets. When i replaced them with 155s now I get wot but it still bogs a little when I back off the throttle, Then comes to life when i back off a little more. RPMs went from 4650 to 4800 with that jet change. I have 150 jets on order.
My question is. Is it possible to lean out this carb other then replacing the jets?
Something I did when I rebuilt it changed it.
I set the float to specs. Is it possible the previous owner dropped the float level to lean out for high altitude?
It ran good before I rebuilt it.
I even went back and replaced all the original parts in the carb.
The only thing I can see that might be different is the float setting."

"Chris:

You didn't say

"Chris:

You didn't say why you rebuilt the carb if it was running good. By rebuilding it, you cleaned all the gum and varnish out of the jets, etc. which had narrowed. Does the accellerator pump have an adjustable pump lever? If it does, set it on the shortest pump stroke and see if that helps. The 150 jets may do the trick. Good luck."

Chris
Did you set the float l

Chris
Did you set the float level as described in the kit or did you consult the manual to get the setting for your model.
We have seen plenty of people rebuild carbs to the spec sheet provided with the kit only to have problems as they were not right for their particular engine.
Always use the specs that match your engine from the manual unless your engine is non standard and you have found a better set up.
Why did you rebuild the Carby ? was it playing up before?
Cheers
Peter C

"I had just bought the boat fr

"I had just bought the boat from an old mans wife who he had passed away.
I rebuilt the carb because it would cut out if i hit the throttle to fast. (Thinking accelerator pump)
What im thinking now is the old women said they had bought the boat from someone who lived in like mich. or someplace. (low altitude). Im in Salt Lake City. If I remember right i thought the float was way low.
I think the old man rather then lean it out with jets, he dropped the float til it ran good.
That might explain the hesitation on exceleration
(maybe not enough gas in the pump resivoir)
I think im dang close. I just didn't think the float level could lean or richen that much.
Unfortenetly its about time to winterize.
Im going to have to wait til next spring to get her diled in.
Thanks, Happy boating.
Chris fom utah."

"Chris
Sounds like you are ge

"Chris
Sounds like you are getting on top of it, hopefully a combination of the right float level and a bit of playing around with your mains will
smooth everything out for you.
You are just about to winterise and I am just about to drop mine in for Summer, cannot wait.
Cheers
Peter C"

"I to have the same problem. I

"I to have the same problem. I sent for a new rebuilt carb and when I received it and installing it, it did the same exact thing at WOT. Backfire thur the carb and sputtered. When I would ease off the throttle it would run better. The carb I ordered was for a 1990 4.3l 175 hp Mercarb 2bb. It had a side fuel inlet. the one that came to me had a front fuel inlet which I could not use. I removed the top of my orginal carb and installed it on the rebuilt.
After reading this post I see you said it had 165 jets and you droped to 155 and it helped. I live in Florida and I rechecked the jets it the rebuilt carb and they were 185 jets. Do you think they could have sent me the wrong carb. I can't check the orginal jets as I sent the old carb back for a core."

"Yes they sent you the wrong c

"Yes they sent you the wrong carb but only based on the fuel line attachment. Check your engine timing. Engine may be too lean at WOT. Did you change the fuel filters? If mech. fuel pump, there is a filter in it also. You need jets for sea level operation; not sure what size."

"Well I sent the carb back and

"Well I sent the carb back and the sent me a replacment I checked the jets to see what they were before I installed it. They were marked (275)Not sure if it is a differnt sizeing or what (I though I was getting 165s back)After installing I test ran and the engine STILL POPs at WOT??? I have replaced the Plugs, Plug wires.cap,rotor,coil and still no change. I removed each plug wire and tested ,thinking it may be a stuck valve but it still backfires. Not sure what else to check or do. Could the electronic modual be the problem?"

I have had this problem on a b

I have had this problem on a buddies boat. It had points and they needed adjusted and so did the timing. It runs on WOT nice now. I also adjusted the carb.

sounds like it's starving

sounds like it's starving for fuel and/or out of time.