No Low Idle Running - Maxum Boat Owners Club

bthorn1983 · 06-22-2015, 03:27 PM

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 · 06-22-2015, 03:39 PM

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 · 06-22-2015, 03:39 PM

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

mmwjr · 06-22-2015, 03:44 PM

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 · 06-22-2015, 03:57 PM

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 · 06-22-2015, 04:05 PM

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 · 06-22-2015, 04:08 PM

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 · 06-22-2015, 04:12 PM

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 · 06-22-2015, 06:06 PM

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 · 06-22-2015, 06:20 PM

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 · 06-24-2015, 11:40 AM

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?

mmwjr · 06-24-2015, 04:31 PM

Quote:

Originally Posted by 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?

The two hoses are to drain the engine and exhaust when winterizing the engine.

bthorn1983 · 06-24-2015, 04:34 PM

good to know, so leave them be during the season? thanks

mmwjr · 06-24-2015, 04:36 PM

IMO since it will not idle even when warmed up if it is the TKS it would mean the circuit is not closing and running to rich, somehow I doubt this is the issue.

When winterized last was gas treatment used and was it ran to ensure it filtered all the way into the carb, if not gum may have built up in the jets.

A small vacuum leak can cause this issue.

Idle setting could be to low but should not have changed itself over the winter.

Use carb cleaner to clean the flame arrestor and let it dry before reinstalling it.

bthorn1983 · 06-24-2015, 04:39 PM

MMWJR, thank you, those all seem like relatively simple things to try and correct, i will work on these things tomorrow and update. If anyone has any other suggestions please comment, other then that you guys have been and are awesome! i hope to have a trouble free boating day on friday and for the rest of the summer.

mmwjr · 06-24-2015, 04:42 PM

Quote:

Originally Posted by bthorn1983

MMWJR, thank you, those all seem like relatively simple things to try and correct, i will work on these things tomorrow and update. If anyone has any other suggestions please comment, other then that you guys have been and are awesome! i hope to have a trouble free boating day on friday and for the rest of the summer.

Call me Mike

hope you resolve the issue soon so you can enjoy the season.

shrew · 06-24-2015, 12:49 PM

@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.

mmwjr · 06-24-2015, 04:30 PM

Quote:

Originally Posted by 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.

Other than the enrichment circuit which uses a temp sensor and solenoid to add gas when cold the rest of the carb is a standard 2 bbl.

Kevlar7r · 06-24-2015, 12:52 PM

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 · 06-24-2015, 01:08 PM

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.