89 225 cough/stall at idle

[Operaman]

Hi,New guy here. All ready learning alot from reading all your posts. Just got the boat and engine. 89 225 Excel on an 89 Mako 210 walk around. At idle there is a cough once in a while and every so often it will stall after the cough. Now, when I test rode the boat it did it much worse and it has gotten better. It also seems to kind of not want to go right away when I start giving more throttle in gear. It will then really go. I have not done a fast nail it. I have been getting used to it. (very responsive sensative throttle) When the engine is going at speed it is fantastic, not a clue of anything wrong. 125 compression across the board. Changed out Racor element, it was rusted on the outside and bowl was filthy. Changed plugs with NGK and gapped to .040 and I removed the fuel filter on the engine side cleaned it out also. Does seem to run smoother. 110 gallon tank is now half full. Added two bottles of Techron and about 8 ounces of Startron. Trying to burn the fuel to replace with new premium. Running Yamalube 2-M. Any ideas? Thanks

[dtmackey]

Burn through the gas and try new gas and throw a set of fresh plugs in it. What is the idle speed?

I also have a Mako 21 and just sold my 225 Excel and bought a 250 Yamaha. Try www.classicmako.com for questions related to your Mako - big following over there.

Sorry to go off topic.

D-

[Operaman]

Just got back and it ran great. Better all the time. Not one cough tonight. Hoping that all the work last night is paying off. Idle is 7 in neutral and 5-6 in gear. Running smoother at all points, especially idle. Boat used to shake like a jack hammer at idle up tp 1,000. Gonna keep burning that gas. Oh yeah. CM is great. I've seen you there. Thanks.

[slim]

raise yu idle speed up to 800 in neutral and turn the mixture screws out about 1/8th of a turn. that should do the trick. a cough or pop is caused from a lean condition and that should do the trick. if not, let me know.

[Ken]

Quote: "Trying to burn the fuel to replace with new premium."

Operaman - check your owner's manual to see what octane rating is recommended - I would be surprised if it is above 87, and running anything higher is just a waste of money [img]tongue.gif[/img] .
Good luck [img]smile.gif[/img] ,
Ken K

[slim]

operaman, as a matter of fact, you might find that 89 is a better fuel for that particular motor because of one thing. as old as that motor is and because it has knock sensor on it, sometimes burning 87 or lower will give off a certain "ping" during detonation. sometimes running a little higher octane in that motor is a must. im not saying its nessesary but if its not running good on 87 then try 89. most of the time on that particular motor and being that old, unless it has been rebuilt, it will have somewhere around 1000 hours on it or even more. it was a hard problem to figure out but it can and will happen with a motor with alot of time on it. so try 86 or 87 and if needed, then increase. but usually 93 is a waste of money.

[Operaman]

Thanks guys. I usually run Premium in my stuff anyway. I realize 89 will probably get it done, but if the fuel sits awhile, especially this fuel we have shoved down our throats on Long Island, at higher octane to start I may have a fighting chance. Could not run it today, poured like a monsoon. I will also tweek the carbs as recommended above by Slim if it starts to cough again.
Thanks again

[dtmackey]

The 225 Excel requires 89 octane at minimum as specificed by the manual. It runs a higher compression 2.6L block.

D-

[Operaman]

Ran Gas almost out and Added Seafoam near the end. Now have added fresh 93 octane. Opened the adj screws 1/8 each and raised the idle ( which did the most for the engine). Gonna try that out. It is flickering between 8 and 9 and once in a while 10 at idle with a slight hicup once in a while, but no stall. Drops to 6 then back up. Maybe back out the adj screws a little more. Hard to tell any difference with three carbs and six screws. Is there a vacuum port to hook up a guage to adjust the screws? Maybe do a Seafoam Deep Creep De-carb in the Bay? Thanks

[jb123]

simply spray gas into each throat or choke each individually with your finger, and listen for any rpm change to isolate a clogged carb as each carb/cylinder acts as a single motor.also, pull each plug wire listening for a NON-change in rpms to isolate also, assuming your plugs are up to par.

[Operaman]

Thanks. Ran it tonight and lowered the idle to 8 and it is coughing still and did stall once. Will do as recommended. Thanks

[slim]

sounds to me like your carbs need to be tore down and cleaned maybe even soaked for an hour in carb cleaner. this is not the same as in the spray can. much stronger. soke all the jets also.

[Operaman]

Slim, makes sense since the Racor was way overdue for change out and the filter on the engine had some debris in it also. I have been told that the low speed circut on these carbs are very small and can be easily clogged. Once cleaned they should stay that way for a while. I have the new Racor element, running Seafoam and will be using only premium fuel. Are they easy to get off? Any special instructions? Thanks

[slim]

yes it is easy to check the idle curcuits. take off the carbs and tear down. there are two brass plugs on the bottom of the bowls about the sice of a pencil. take them out, give a quick blow and hold up to the light. if you see a good round hole and no blockages, thats good. take out the brass welch plugs on the top of the carbs and make sure all the orrifice holes( i think 4) are all open and finally, take out the air mixture screws, insert the tube from a can of carb cleaner and press. it will shoot out of a little hole in the carb throat. this should do it for the idle curcuit. let us know if you need more help. if you need to, email me at slimiam72@cableone.net

[Operaman]

Slim, Well done. Took them apart one at a time so I wouldn't mix up the floats. Cleaned all of the circuts. My middle was clogged a little also. Before this fix I would lean on the throttle and nothing. Then the boat would take off like I holeshotted it. Now it idles and midrange is smooth also. After I cleaned the carbs, started it up and the idle was at 1200-1300. Guess that is how the previous mechanic allegedly cleaned the carbs. Had to adjust the cable and the linkage for the idle. Thanks very much.