carbs

[badfish888]

2002 merc 125 saltwater, strait 4 cylinder, engine runs great, idles ok (on 2 cylinders) how often should i have the carbs (serviced) what do they do at a marina for the service, iv read i can submerge them in "seafoam" over night and that will eat all the carbon and stuff out of em.

just looking for any input, basically the boat was purchased new in 2002 by my buddies dad, and idled around long island sound, with the occasional cruise. He said he paid the marina to do the service at the begining and end of every year, (gave me the receipts). when asked how much he uses it, he said a full tank lasted him almost 2 years?!?

when i got the boat last year, i drained the tank, filled with 80 gallons of 93oct. and a bottle of the mercuy carb cleaner. first time out i kept it at half throttle and close to shore..............just in case....... the motor fell on its face a few times coming out of the hole, but eventually cleared herself up and runs like a top. i ran almost 4 full tanks of 93 through it last year, and 2 of 87, and it still ran great when i stored it. i ran STABIL through it before storage. but back to the carbs, all the reciepts i have for it, none of em are for a carb service.

what should i do?

 

[SparkieBoat]

Re: carbs

if the carbs are working fine and you keep sea foam or stabil in the fuel you can go many years with out messing with them, I have a 1989 110 Rude that I was the first person to ever take the bowls off of the carbs since it left the factory. I broke the factory seals last year.

 

[Faztbullet]

Re: carbs

As long as you run a stablizer with a fuel additive such as Quickleen, Carb X, Carbon Guard, Ringfree or Seafoam they will keep clean carbs clean so you should need no servicing

 

[badfish888]

Re: carbs

do you guys run sea foam in the fuel like an injector cleaner, or use it to soak the carbs?

 

[badfish888]

Re: carbs

bump

 

[SparkieBoat]

Re: carbs

add sea foam to your fuel tank..soak carbs in laquer thinner or carb soak stuff.

 

[ticondo46]

Re: carbs

If your carbs are not leaking, don't worry about them too much and don't go looking for problems that don't exist. I have a 1997 Mercury 115 (which is nearly identical to your 125, except for jet sizes etc). To this day, after 1,000+ hours, I've never taken off the carbs (and I never used any stabilizer either!). If the fuel that you use is always clean, then there shouldn't be any crud in the carbs. Avoid ethanol gas. The engine can take it, but I wouldn't be too sure about your ageing fuel lines and tank connections. In doubt, go for the real non-ethanol stuff if you can find some in your area.

As an added precaution, change once every couple of years the in-line fuel filter which you can easily reach on the starboard side of the motor. And there are also some bronze drain screws on the bottoms of each float bowl. You can just about reach them without too much trouble. Back them out at the end of each season (no need to take them completely off, just slacken them), let them leak their juice and retighten once dry. That would take care of any stagnant water in the bowls. Regarding idle screws, don't attempt to adjust them with the engine on muffs. You need to do it with the lower unit in the water, and with the motor at its normal operating temperature. It's fairly straightforward: screw them both in slowly until the engine starts to bog down, and open them bit by bit half a turn each, until the engine idles comfortably. Finish it off with the big nylon finger screw on the throttle linkage, in order to get about 900 RPM. It may be that you will have to further adjust after a run, with the engine at working temperature, but then you will find that further adjustments are rarely needed. This is one heck of a reliable engine. If you use clean gas, a good TCW-III oil and proper (and clean) plugs (NGK BPZ8-HN10, I think), your motor will run for eternity. To me, it's the equivalent of a tractor engine! Somewhat unrefined, but soooo reliable!

 

[badfish888]

Re: carbs

i do love this engine....so far, and i dont think ill take the carbs off then, i ran a full tank of the mercury fuel injector cleaner through last year, then before storage i ran stabilied fuel through it, so to fiw my erratic idle and the horrible 2 to 4 transition, you think i should just have a shop "link and sync" em? what were you talkn about with the idle screws? thats not syncing em ....is it?

 

[ticondo46]

Re: carbs

If nobody has ever taken them apart, then you shouldn't need to resync your carbs if they were properly adjusted during manufacture (and we can assume that Mercury did that correctly at the factory!). They wouldn't normally move out of adjustment on their own. You can actually do a visual check as follows: carefully take off the rod linking all four carbs (careful not to bend the rod or break the plastic bushings!), and check whether the four throttle valves on the carbs move freely all the way from minimum to Wide Open Throttle. Then while reconnecting the sync rod, make sure that none of the throttle valves move away from minimum. They should firmly rest on their lower stops. Don't forget that on this motor, the carbs don't open until 2000 RPM (none of them). From idle to 2000 RPM, acceleration is only a result of spark advance, and only the top two cylinders have idle jets. The lower two get minimal fuel/oil through their main jets, just enough to prevent them from seizing up but not enough to provide any significant power. At 2000 RPM, all four throttle valves open at exactly the same time, and a little snail cam (which you can see on the left side of the motor) presses a little button on an accelerator pump which squirts a bit of fuel into the lower two cylinders (those that don't have an idle jet in their carbs). This little squirt prevents some spluttering that would occur if the lower "starved" cylinders were just fed off the main jets without any extra enrichment. I agree, the transition is awesome, but it works!
Your last question: no, idle screws are not "synching". It's just a very minor adjustment, although its effects are spectacular. My suggestion is that if you are not too confident in carburation issues, jut concentrate on the idle screws. You can't do much damage (except if you screw them down all the way and tighten them, in which case you may mess them up pretty badly). If you manage to get a nice idle, you're a winner, and if not, then you are still in time to go to a professional mechanic without looking like a total schmuck who fiddled his toy and broke it!
One last thing: idle screws are only to be touched once you are sure that all the rest is OK: plugs (the right ones, and clean), fuel filter, compression, engine temperature.

Enjoy!