anyone good at tuning the 2-barrel mercarb, 2002 year?

[ron7000]

after researching carburetor technology, mostly on holley's, I'm once again ready to go after fixing my bog at 2000-2200 rpms on my 3.0L.<br /><br />I've already replaces the power jet, swapped out the original 1.55mm main jets with new jets, running 1.65mm main jets now, and tried all 3 accelerator pump lever settings and inspected the acc. pump.<br /><br />My next steps are to make a fuel pressure guage at the carb and try different float levels. I may even pull the entire carb off the motor and clean it out, hopefully the base gasket will survive.<br /><br />This bog/hesitation is caused by a lean condition. Does anyone know which model/year mercarbs had the inadequate acceleate pump size? However, I don't feel the accelerator pump is at all the problem because I get the bog no matter what, including acclerating very slowly. This tells me the problem is more involved and has to do with the main metering circuit and/or the power circuit. All my knowledge is based on holleys, if anyone has insight on the mercrap 2-bbl please share.

 

[Blk-n-Blu]

Re: anyone good at tuning the 2-barrel mercarb, 2002 year?

Ron, Here is a service bulletin that might help:<br /> http://www.marinemechanic.com/site/page152.html

 

[ron7000]

Re: anyone good at tuning the 2-barrel mercarb, 2002 year?

thanks,<br /><br />

MCM 4.3L 'Surge' or 'Popping' Condition above 4000 RPM,<br />S/N 0F114600 and Below<br /><br />If a customer is having this condition, install 1.60 mm main jets; <br /> 3302-810923 1.60 mm Main Jets, 2 required.

I've had this problem intermittently at 4200+ rpms when skiing, even with the 1.65mm jets. It might be bad gas, I won't know till I run it out and fill with fresh fuel.<br /><br />What has me baffled is the plugs are still white with the 1.65mm jets. shouldn't they at least have some carbon on them?

 

[Bondo]

Re: anyone good at tuning the 2-barrel mercarb, 2002 year?

What has me baffled is the plugs are still white with the 1.65mm jets. shouldn't they at least have some carbon on them? <br />

Is the Timing Too Hot ?????<br />Coffee & Cream is the Color I like to see...........

 

[ron7000]

Re: anyone good at tuning the 2-barrel mercarb, 2002 year?

no, it's set to 2deg atdc with distr. jumped, according to service manual instructions.

 

[jimmbo]

Re: anyone good at tuning the 2-barrel mercarb, 2002 year?

At 2000 rpms you should be pulling fuel out of the main fuel ciruit so richening up the accellerating pump circuit really won't solve the trouble. Is the float level and float drop(if required) set correctly? The power circut is an on/off type, easy to check for binding once the carb top is off. What about the choke, is it opening fully? I wonder if the trouble is something else and not the carb. Low fuel volume and pressure can do this too, check the pump/filters. Perhaps your timing isn't advancing as it should or you have the wrong module in the distributor.