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Tan
Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10618
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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I chatted with you folks last week to get my motor running

Customer Question

I chatted with you folks last week to get my motor running and it is running now but only at about full throttle at half choke. when I throttle down to idle it cuts off.
JA: Sometimes things that you think will be really complicated end up being easy to fix. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so the Marine Mechanic can help you best.
Customer: did you get what I just typed?
JA: Is there anything else the Marine Mechanic should be aware of?
Customer: it is 2 1986 25 hp Mariner
Submitted: 1 month ago.
Category: Boat
Expert:  Tan replied 1 month ago.

Hello, I'm Tan. Welcome to JustAnswer. I'm reviewing your question and will reply momentarily.

Expert:  Tan replied 1 month ago.

Have you done a spark and compression test? If yes what were your results? If no we need to start with those 2 tests first.

Customer: replied 1 month ago.
Expert:  Tan replied 1 month ago.

If yes what were your results? What was the compression and how wide a gap did the spark jump?

Could I get the engine serial number please?

Customer: replied 1 month ago.
can you hold just a minute
Expert:  Tan replied 1 month ago.

Yes.

Customer: replied 1 month ago.
0B116546
Expert:  Tan replied 1 month ago.

What were the results of the compression test? Do you have compression on both cylinders?

Do you have spark on both cylinders? Will the spark jump a 7/16" gap on a spark gap tester?

Customer: replied 1 month ago.
I am sorry, I did a spark test but not compression test. It seems to be more of a fuel things as it would not run at all before it was flooding now it runs but will not idle
Expert:  Tan replied 1 month ago.

Have you tried adjusting the idle jet at the top of the carburetor?

Did you rebuild the carburetor?

Customer: replied 1 month ago.
I adjusted the idle screw and cleaned the carb and new gaskets to no avail. Did not replace idle screw or needle valve as they looked good to me.
Expert:  Tan replied 1 month ago.

Will the engine idle if you close the choke slowly with engine running?

Customer: replied 1 month ago.
No. It will only run at half choke
Expert:  Tan replied 1 month ago.

Half choke is not enough fuel or the engine is sucking air. When you had the carb apart did you clean the idle tube in the carb that runs from the float bowl to the top of the carb with a piece of wire?

Customer: replied 1 month ago.
No, I did not. Along that line. The hole in that tube was not centered it was off to one side. Would that cause a problem?
Customer: replied 1 month ago.
Also, when I pumped the primer bulb, gas would come out around the tube where it gets smaller about half way up. Is that normal?
Expert:  Tan replied 1 month ago.

No the tube is where the carb pulls fuel for idle if that tube is clogged the engine will not idle.

Does squeezing the primer bulb help.

Did you do a complete rebuild of the carb including the fuel pump side of the carb?

Expert:  Tan replied 1 month ago.

No that is not normal. The primer bulb should not pump anymore fuel once the inlet needle shuts the flow of fuel.

Customer: replied 1 month ago.
I did the fuel pump and diaphram. Can the idle tube be removed?
Expert:  Tan replied 1 month ago.

No, If idle tube is cracked or has a hole you have to replace the carb.

Customer: replied 1 month ago.
If not what can you do to stom the fuel from coming out?
Expert:  Tan replied 1 month ago.

There are 2 tubes one small tube then a larger tube. The larger tube is for high speed. If you have fuel coming up through that tube then the inlet needle in the carb isn't seating correctly causing the engine to run to rich.

Customer: replied 1 month ago.
OK, I understand. I will try those things. Is there any way to get in touch with you personally or is it just pot luck when I get on line?
Expert:  Tan replied 1 month ago.

Ok. You can get me by asking for me or posting here in this link. http://www.justanswer.com/boat/expert-suntan/

You can always just post back as you have been to this same question.

Customer: replied 1 month ago.
OK, thank you very much, Tan. I will try those things. I appreciate your help.
Expert:  Tan replied 1 month ago.

Ok let me know how it goes.

Thank you.....Tan

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