1989 Mariner 50hp 3 cyl ...running rough at low speeds

[davemillertime]

I Have a 50 hp Mariner 3cyl ,seems to be smoking & running rough at low ""Trolling "" speed tach bounces from 7-800--1000 rpms ....It Had that autoblend system on it ::JUNK:: ..Untill I pulled it out & put it in the trash can ..Now Iam mixing my Gas/oil in my tank at 50:1....Also runs real good at High speeds ? ... Not sure if there is a Low speed adjustment or what should I check next ??

 

[sutor623]

Re: 1989 Mariner 50hp 3 cyl ...running rough at low speeds

I Have a 50 hp Mariner 3cyl ,seems to be smoking & running rough at low ""Trolling "" speed tach bounces from 7-800--1000 rpms ....It Had that autoblend system on it ::JUNK:: ..Untill I pulled it out & put it in the trash can ..Now Iam mixing my Gas/oil in my tank at 50:1....Also runs real good at High speeds ? ... Not sure if there is a Low speed adjustment or what should I check next ??

Man everytime that I have had this issue it has been an issue with my ignition system. Is there a low speed fuel adjustment on this model?

 

[davemillertime]

Re: 1989 Mariner 50hp 3 cyl ...running rough at low speeds

Yes I believe it does ...My service manual shows it has a idle mixture screw right next to the fuel bowl vent jet ...The only problem I can see is ....2 carbs ....what one do I adjust ????????

 

[sutor623]

Re: 1989 Mariner 50hp 3 cyl ...running rough at low speeds

Yes I believe it does ...My service manual shows it has a idle mixture screw right next to the fuel bowl vent jet ...The only problem I can see is ....2 carbs ....what one do I adjust ????????

Well I wouldnt say just go and adjust them to start off. But if it were me I would try. With the motor off, pick a carb, screw the screw in TIL IT LIGHTLY SEATS, but make sure to count how many turns by the 1/4 turn. Then back it back out to where it was. You can start by screwing BOTH in 1/4 turn and seeing how it idles. It is a hard test to do when the motor is not under load though, dont trust doing it on muffs or in a bucket. See how it does. If you can get it to idle better in gear, awesome. Then we will show you the thread on here for a Link and Sync.

 

[sutor623]

Re: 1989 Mariner 50hp 3 cyl ...running rough at low speeds

One other thing, is this a new to you motor? Did it idle well last season? If it did you just need to run some seafoam through it, and then let it set. If that doesnt work you may need a decarb. If the motor is new to you, you can tinker a little with the idle and see if that helps.

 

[davemillertime]

Re: 1989 Mariner 50hp 3 cyl ...running rough at low speeds

No ...Its Not New to me ...Ive had the Boat / Motor for 3 yrs ...the first year It ran GREAT ...then I had a problem with the autoblend system so i started mixing the gas directly . now for 2 yrs its been running alittle OFF ...Also it did stall today when I took it out of Gear But started right back up .."""Plugs were Loading up "" so I went to get it on plane & I could tell 1 of the plugs were fouled ...but after 3-5 seconds It was running on all 3

 

[CharlieB]

Re: 1989 Mariner 50hp 3 cyl ...running rough at low speeds

If plugs are fouling either the carbs are too rich or the plugs are about done, or BOTH.

Clean or change the plugs, run the motor for a few minutes then pull the plugs and look at them. See if they are blackening from excess fuel.