No Low Idle Running

[bthorn1983]

Ok guys, relatively new to boating, only have had outboards before. I bought a 2008 Maxum 1800 MX. I have gotten it out this year, it starts but then shuts off relatively quick unless i can give it some gas, then it will run. If i try to just put around it dies, this makes docking pretty tough, have to come in hot. I am very mechanically inclined (with cars) and am coming to the conclusion that this could be due to bad gas. the guy i bought the boat off of said that the guy who winterized it for him may have done a shotty job. Under high accelleration the boat runs good. at low idle it stalls out and has a hard time restarting. Looked at the plugs they look good. The boat did have about 2/3 of a tank when i got it from the previous owner, i have topped it off with premium gas and a bottle of octane booster. after reading some threads in here, im thinking i might have to drain the gas tank and start fresh. I also did not see any water/fuel separator nor an external fuel filter, are they located in tank? Any and ALL advice is much appreciated.

[mmwjr]

welcome aboard.

what engine do you have?

Does it have an electric fuel pump? If yes may be a week oil pressure switch that provides power to the pump. Higher rpm providing enough Op to keep the switch closed.

Carb or fuel injection? If carb Choke or TKS?

[bthorn1983]

sorry should have said that, 3.0 Merc 4cyl. Looks like a mechanical fuel pump, Carburated.

[mmwjr]

Thanks. Merc offered a carb they called TKS (turn key start) It eliminated the choke and incorporated an enrichment circuit by means of a solenoid and a temp sensor, these are know to go bad and will cause your issue.

[bthorn1983]

what is the best way to know if that is what i have? and how much are they to fix? is it just a solenoid?

[mmwjr]

On top of the flame arrestor it will say TKS or remove the flame arrestor and see if there is a choke or not.

Go to this site and find the manual for the carb

Boatinfo - Mercruiser Service Manual nr. 16 - 1993-1997 - Engines GM V8 454 & 502 CID (Gen V - Gen VI)

Manual # 41

[bthorn1983]

wow that is a wealth of information! thank you. Should i rule out bad gas and go with this? i just dont want to drain out 20+ gallons of gas if i dont have to.

[mmwjr]

There should be a gas/water separator near the fuel pump. Remove it and pour the contents into a glass jar to look for water or phase separation (two separate color liquids) that can occur with E10 gas.

if this checks out then I would suspect the carb.

Note I have horror stories with this carb but have never worked on one myself.

[Baby Blue]

If it does have a choke plate make sure it's fully opened when warmed up. I have to adjust mine twice last year to get it just right. Made a world of different in starting and idling.
BB>

[bthorn1983]

thanks a lot, if the tornados stay away im gonna look at it when i get off of work today and ill update tomorrow what i find.

[bthorn1983]

well got some gas in a jar, let it sit over night, no separation. Also i do NOT have a water/fuel separator in line between my tank and my fuel pump. Any other things i should look at before i go buy a new solenoid for the TKS system? Also, i have a question, should the manifolds be drained of fluids? there are those two hoses that come up to the right of the engine, how often should those be drained?

[shrew]

@Mike. Do you know if these carbs use a pilot jet? This sounds a lot like a clogged pilot jet. This was the exact type of issue on my dirtbikes.

[Kevlar7r]

Timing could cause idle issues too. If it is somewhat retarded, it may not idle. At speed, the advance brings it into a range where it will run.

[bthorn1983]

it doesnt really appear that the timing is very "adjustable", i could be wrong though, it does have the TKS system, i did start it up for about 5 seconds yesterday (dont have muffs) and without the air filter on it, it actually seemed to run pretty good, going to take it to the water and play around with some stuff. I am still hoping it is bad gas, but its not seeming so. Is it possible to use some carb cleaner by spraying into the carb to clean it out? or do I HAVE to disassemble the carb? I will check timing tomorrow as well, just to hopefully rule that out.

[Kevlar7r]

Well, you may have just destroyed your impeller. Running for just a few seconds without water is enough to melt the little rubber fingers away.



Go get some muffs. They are like $10 at WalMart, which is a bargain compared to an impeller job.



Your next time out, watch your temp gauge like a hawk, if that needle goes over 180 shut down immediately.

[bthorn1983]

man, that is not what i wanted to hear.... i really really hope nothing happened.

[bthorn1983]

Now im at work, all freaked out that i ruined my boat before we are supposed to go to Jobbie Nooner on friday. Any other solutions for the low idle no run issue that im having? Something easy to check and possibly easy to fix? Ill Check timing, checked fuel, ill possibly get a new air filter, checked spark plugs they look good, ill fiddle with the choke and such when its in the water, hopefully it wont overheat now that i ran it without muffs on... dang it im freaking out.

[Kevlar7r]

Well relax, there is nothing you can do to change the past, its done. But, you can learn from it and change the future.



These boats don't have an air cleaner, only a spark arrestor. It can be cleaned with solvent, and washed out with water, the LET IT DRY before starting the engine. You don't want yo suck any water in, but, if there is a backfire and solvent residue on the spark arrestor, it could mean a fire.



It is unlikely that a clogged spark arrestor could cause your problem, as the air flow is very low at idle. You'd be more likely to see top end problems with that.



Is it possible your idle is just set too low? What rpm is it idling at?

[bthorn1983]

well if i could get it to stay idling long enough i could tell, i will check tomorrow when i get it in the water. Like i said, i have to pretty much just get the engine running and then give it 3/4 gas to keep it from stalling back out. now yesterday when i had it running for a few seconds in my driveway it ran ok with the spark arrester taken of, probably a coincidence and i really didnt give it a chance to really run, so it wasnt warmed up either. Im just curious how if it was running well when put away last year, how it could all change so much at the start of this year.

kevlar, would it be possible just to give you a call later today? might be easier to describe over the phone. If not its cool we can keep it in the forum. I sincerely appreciate your help.

[Kevlar7r]

Lets keep it in the forum, for 2 reasons.

1. Putting the conversation out there can help others.

2. Phone service at my work is spotty, and I have a lot of meetings today.