running lean? carb adjustment?

hullofalottatrouble · Aug 21, 2005

first.. the forum is great you guys are all helpful.. and your advice is much appreciated.. 1982 mercruiser 260 rochester 4bbl quad carb bought boat used.. took out first time ran fine for an hour or so then ran hot.. got back to dock slowly.. never ran it in the red but engine was definitely warm.. no steam or smoke or anything melting.. have since fixed overheat situation.. now running lean.. i do not believe it was running lean before overheat situation.. starts runs great at first.. thou give it a hard run and back to idle.. idle is a little rough.. will idle all day but a little rough.. try to get into gear and dies.. if someone closes choke a bit will go into gear and run.. idle all day again and dies when into gear.. so close choke a bit and get it home.. so far.. comp test -7 cylinders around 150+ -1 cylinder 125 dry - 150 wet vacuum test on muffs on trailer -14 approaching 15 but definitely under 15 steady at idle -up to 19-20 with increase in RPMs then back down to 14.. -no impact on RPM of vacuum reading from oil or propane test.. fuel line inspection -crack in line from tank to water/fuel sep.. does not appear to have been leaking fuel but will be replaced.. seemed to run about 2 ridges deep on 3/8 nipple -slight crimp in fuel line near connection with carb filter -carb filter clean -carb itself is pristine.. could eat off it.. -fuel water sep is clean -line connection carb and primary vacuum has crack does not appear to be impacting anything at idle but will be replaced..

Bondo · Aug 21, 2005

Re: running lean? carb adjustment?

Well,.............. The Choke is Supposed to be Fully Open after the motor warms up,....... So,.. That's Not the Problem............... Most of those old 260s had a Rottenchester Carb...... Your's is going Lean at idle,.... A Carb. Rebuild Might fix it,... But My experience with the Rottenchesters is that the Carb Casting is Probably Worn Out around the Throttle Shafts,+ Allowing Air to get past, causing the Lean condition..... It Could be a Fuel Flow issue,..... But,... I'm Betting on a Wore Out Carb.........

hullofalottatrouble · Aug 21, 2005

Re: running lean? carb adjustment?

Bondo · Aug 21, 2005

Re: running lean? carb adjustment?

Well,......... It was Rebuilt Over a Year ago,....... When was the carb NEW,..??? Rebuilding a rochester is at Best a 50/50 Shot,.... I'd say it Needs it Again,........ Probably some Sh!t in the Low Speed Circuit....... Or,.... If you're calling a rebuilt carb New,...... It Might need Replacing......... I Really Doubt it's a matter of Adjustment...... And,.......

i do not know what brand of carb i have,...so within the carb assuming its good what adjustments can be made?

It Appears to Me,...... That You're Already in Over Your Head...................

hullofalottatrouble · Aug 21, 2005

Re: running lean? carb adjustment?

"It Appears to Me,...... That You're Already in Over Your Head..................." bondo.. thanks for the reply.. um.. ya know you can respond to questions and not be an a-hole about it.. but if it makes you feel better to be an a-hole.. good for you.. good luck with that.. i bet you will have a lot of very happy people at your funeral.. i havent had the boat for more than a month.. and havent spent more than a couple hours on it.. have spent little time looking at or even thinking about the carb.. the boat is kept over 40 miles from home so not like i can do in my back yard and look.. but anyway.. good luck with being an a-hole..

hullofalottatrouble · Aug 21, 2005

Re: running lean? carb adjustment?

rebuilt was wrong word.. carb was new in july 2004.. NEW CARB in 2004.. that make you feel better?!?

Bondo · Aug 21, 2005

Re: running lean? carb adjustment?

I'm Truly Sorry you don't like My Honesty,+ Too the Point writing style............ All that I can do is Reply to the Info that You posted............. If You don't Know what you're Looking At,.. or What You Own,..... And,..... If You don't have a firm grasp of the American English Language,........ I guess You Are in Way Over Your Head............ This is the internet,.... I Can't reach over there,+ Fix Your Boat For You................. A$$hole or Not,.......... Your Carb has $h!t in the Idle Circuit......... Take the damn thing Off,+ Rebuild It..............

so within the carb assuming its good what adjustments can be made?

I'm Assuming Nothing,....... And,..... I've Already Told you Where to Look...... A$$hole or Not,.......... All the Info I can give you does Absolutely No Good What So Ever,......... If YOU Don't Know What I'm Talking About......... If I give you All the Specs on a Rochester Carb,+ it turns out you've got a Weber,..... Then What,....... Let Me Guess,....... It's My Fault that You don't have a Clue......... Ayuh,......... Get Real,..... You Need a Mechanic,.. Not Advice.......

hullofalottatrouble · Aug 21, 2005

Re: running lean? carb adjustment?

bondo.. you can mmake suggestions recommendations without adding insult.. plain and simple.. others have done it.. everything in your posts was appreciated until the insult.. no need to add that.. i supposed you think you were born a boat expert or an expert on everything else in your life and have never ventured our of your realm of expertise to learn something new??? come on.. and thanks to many other people on these forums i have learned a heck of a lot about boats that i was clueless about 2 months ago.. and have been able to successfully repair several things on this boat.. overheat problem, shift cable, trim pump, riser gasket.. it just bought it 2 months ago.. no i havent looked at the carb.. give a brother a chance.. sheesh..

Don S · Aug 21, 2005

Re: running lean? carb adjustment?

If you're closing the choke by hand so you can shift gears and go, then the reason it's working then is because you have a vacuum leak somewhere. When you close the choke a little (or a lot) you are adjusting the air/fuel ratio. The vacuum leak is allowing to much air into the engine and when you close the choke you stop some of that excess air. I would also question the compression test. I have never seen compression that close in any engine. Read the link below. Service Bulletin 97-25

agitator · Aug 21, 2005

Re: running lean? carb adjustment?

flapjack 56, the only thing that saved you from a worse tirade from Bondo is the fact that you didn't identify your boat as a Bayliner. He would have really heaped some crap on you then. There are a lot of knowledgable people on here eager to help without treating you like an incompetent idiot. Hang in there.

hullofalottatrouble · Aug 21, 2005

Re: running lean? carb adjustment?

Don, Thanks. I am totally with the concept of closing the choke which bring the air/fuel ration down.. I read another post and i also seem to have a problem with going WOT. I did that last time out and it seem to slow me down a bit.. it was just within that last 1/2 inch of throttle or so.. so if this is a vacuum issue.. where do i begin?? Or what are good questions to ask a mechanic? Thanks Rob

hullofalottatrouble · Aug 21, 2005

Re: running lean? carb adjustment?

agitator.. thanks.. ive learned a ton on here.. ive read eleswhere people test for leaks in carb gaskets with propane? or water or something else around the gaskets.. if i have that trouble at WOT is it a fuel filter issue as well perhaps? read that else where too.. but i do think the vacuum issue is a good one to investigate.. where do i start? thanks again to everybody else who has added their contructive advice or thoughts on here.. much appreciated..

imported_scott_m · Aug 22, 2005

Re: running lean? carb adjustment?

Often times after installing a new carb they will seat in on the gasket, resulting in a vacum leak between the carb and manifold. Try to LIGHTLY (don't have torque specs) torque down the bolts. I had mine off last spring for a rebuild and had some issues - the carb had losened up quite a bit, so just tightened down the bolts (cross pattern) and that seemed to help.

Don S · Aug 22, 2005

Re: running lean? carb adjustment?

The first thing to do is hook up a vacuum gauge to the intake manifold and verify there is a vacuum problem. Using propane to check for leaks is ok on cars, but propane is heavier than air and quite explosive and you don't need propane filling the bilge of your boat. Oil normally works fine, and will seal the leak temporarily and make the engine run different when you squirt it on the leak. If the leak is big enough, you can hear the oil suck into the leak.

Adam13 · Aug 22, 2005

Re: running lean? carb adjustment?

your choke is probolly electronic and is supose to do that when the motor gets warm enought like they said above

hullofalottatrouble · Aug 22, 2005

Re: running lean? carb adjustment?

thanks don..

hullofalottatrouble · Aug 22, 2005

Re: running lean? carb adjustment?

Don, what reading would i be expecting on the vacuum gauge is steady 20Hg correct? and if it is steady low that is an indication of a vacuum leak? where would I want to squirt the oil to test for leak? Where are the most likely places? Any thoughts on this being a fuel pump/filter issue? Clog somewhere or leak in the fuel like?

hullofalottatrouble · Aug 26, 2005

Re: running lean? carb adjustment?

vacuum test results.. ran a vacuum rest on muffs on the trailer.. 14 fairly steady.. i ran some oil and tried the propane test and neither seemed to have any affect on the RPMs or vacuum reading.. ran the RPM up got the gauge up to about 19 and back to 14.. so if i do have a leak somewhere i didnt have any luck in finding it.. time to check the fuel lines??? or should i continue on the vacuum leak path???

hullofalottatrouble · Aug 28, 2005

Re: running lean? carb adjustment?

new info in first post.. editted for current info.. thanks

hullofalottatrouble · Sep 3, 2005

Re: running lean? carb adjustment?

Update for you and thanks for the help so far.. i appreciate it.. I finally got the pressure gauge t into the fuel line and tested.. it was 2.5psi at idle and even 2.5 at higher RPM. So I put a vacuum gauge in on the intake side and it was like 5 in HG way too high. So I bypassed the anti-syphon valve and it read pretty much 0 HG. So put the pressure gauge back in and read 5.5 PSI.. looks like that helped.. going to replace anti-syphon and hopefully call it fixed.. pick up and all filters are perfectly clean.. I still cant get in there and adjust the mixture with the carb on and engine running.. i bought that flexi thing.. it just doesnt fit.. so I pulled off the carb and set them both at 3 turns.. when i had the carb off i noticed it looks like the rebuild guys drilled new holes and taps for the carb bolts.. its a Edelbrock Performer 2101 intake? the carb is actually a carb for a 260R but I have a plain old 260 based on the documentation i have seen and the serial number.. so what gives with that? they mix and matchin intakes on me? I still do have a vacuum leak issue. vacuum gauge reading was actually worse this time than last.. it was still more or less steady but ready between 12-13 hg instead of 14-15 which it was last time around.. so some have suggested it might be carb rebuild time.. or at least kit time? any thoughts on that? Thanks Rob

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