Carb adjustment

[Karla45]

Just got my boat back from mechanic and it is running pretty good. I did not want to pay $125 to have them do lake test and make any adjustments. he said i may need to make some small adjustments. I had a problem today with it dying on me. It is coughing some while idling. Then i had it do something had never done before. I would start it and go real slow but when i would go to accelerate it would die. He told me i may need to adjust idle speed but i do not have a tach. Which should i try first the idle speed or the carbs? I am not sure which way i need to turn the idle screw on the carbs. Does this mean it is running to lean or to rich. He told me he adjusted more on rich side to be safe. I am looking into buying a tiny tach or something similar.

 

[Frank Acampora]

Re: Carb adjustment

Without a tach, doing either is like trying to go to Houston when you don't know where you are. Are you in Dallas? or mexico? Which way do you go.

So at the very least, try to borrow a tach.

I would adjust the idle speed first. On the timing tower at the fitting where the carb link attaches there is a screw and locknut. At idle this screw bears against the engine block, limiting how low the engine will idle. Loosen the locknut and screw in the screw 1/8 turn at a time until the idle is high enough so the engine does not stall when put in gear yet it does not "clunk" excessively.

Check the sticky, FAQs, at the top of the this page for the post: Synchronizing carbs and timing. It will describe all you need to know.

 

[Karla45]

Re: Carb adjustment

I just ordered a tiny tach but it will take a couple of weeks to get. It is actually already in gear but when i give it more gas it dies. It did this several times and then kicked in. I do not know anybody who has a tach but I may ask some members in my bass club tuesday night. It is looking like I wil not have to winterize my boat this year. It is december and the temp was 64 today.

 

[MWBROWN]

Re: Carb adjustment

I have a 1984, 85 HP.

Some time ago, one of the guys explained that the "book" idle adjustments are too lean for today's gasoline. I had the same trouble that you explained.
I simply followed his suggestion. I took of the cover, took out the rubber plugs from the carb plate on the front of the engine. Then. one at a time, I gently screwed the idle screws in ( clockwise ) until I felt them stop, the out 1 1/4 turns, which seemed to be the best idle.
Then I turned each one out 1/4 to 1/3 turn more, even if the engine sounded like it slowed slightly.

The result was easier starting, better idle under load, and no bogging under acceleration.

To prove what I did. I set the idle screws back to factory and the same problems came back.

I hope this helps.

No winterizing here either. 52 today.

My enging also idles at about 750 under load.

 

[Karla45]

Re: Carb adjustment

Thanks guys i will follow your advice. Do you live close to Lake Guntersville in Alabama? I am going to bama over Christmas and my sister now lives right by Guntersville, unfortunately I will not be able to take boat and take advantage of the great largemouth bass fishing, darn

 

[ericspainter]

Re: Carb adjustment

i am having the exact same problem with mine.i just got it and i rebuilt /cleaned carb and took it out on saturday and it idles fine but if i give it gas it dies .i thought it was something with my carb but maybe not now.i read the sticky but mine is a 40 hp 1996 anything i need to do different

 

[jason32038]

Re: Carb adjustment

Sounds like your mechanics adjusted the mixture screws too rich to be safe. Do like frank said in his sticky and turn each mixture screw in 1/16th and try again OR i'd reccomend that you wait and save up that $125 and have them do it on the water that way you know it's done right...hopefully. lol

 

[Karla45]

Re: Carb adjustment

well the weather starting to get colder so i think i will soon be winterizing although warm weather can start here in feb so not sure if i really need to do anything other than putting stabilzer in for the next couple of months. It will be couple more weeks before get tiny tach, so i probably will not mess with it for a while. will let you know results when worked on. thanks

 

[ericspainter]

Re: Carb adjustment

update on mine.i removed carb and cleaned again adjusted air fuel needle to 1 turn out and it ran like a champ with some minor adjustments to the needle for max performance.