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Ask Dominick Your Own Question
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I just completed the rebuild of my 1987 20hp mercury carb.

Customer Question

I just completed the rebuild of my 1987 20hp mercury carb. The engine is still difficult to start. I have a few questions please.
1. When I use the fuel tank's primer bulb, after a few squeezes fuel not only comes into the main carb throat but spews out at the upper portion of the carb. This seems abnormal to me and may be a fire hazard?
2. When replacing the float needle furnished with the rebuild kit, are you supposed to replace the needle seat as well? I found a very small red colored object in the kit but there were no instructions included.
3. If you replace this red needle seat, is there a top or bottom in order to properly insert? It looks like there is a small raised "rim" on one side of the seat.
4. Where is the adjustment screw for the rich/lean side of the carb? Is it the long needle with a spring behind located on the face of the carb? If so, how many turns should it be backed out once it is fully tightened in a clockwise position?
5. Anything else to check as to why the engine is hard to start after the carb rebuild? Again, the kit came with no instructions so I just tried to replace the new parts in the same position as the old ones. The carb was blown out with air and thoroughly cleaned with carb cleaner.
I also replaced the water impeller with a whole new kit. When I put a water hose "muff" on the lower unit, water will not usually come out the "pee tube" or will only do so after the engine has run for a while and at a high rpm. No water ejected at idle. I have blown through the "pee tube" into the engine and there does not seem to be a blockage.
1. What might I have done incorrectly on the rebuild?
Submitted: 1 year ago.
Category: Boat
Expert:  Charles replied 1 year ago.

Hello, my name is***** will assist you today.

Would you please post the part number of the kit that you used?

Is the carb still on the engine?

When you tried to start it, did you use the primer on the carb first?

Customer: replied 1 year ago.
I installed an OEM kit # *****I did pull out the choke twice then leaving 1/2 out as per cold starting instructions. Yes, the carb is still on the engine.What does the dash pot do?Did you also receive my attached question regarding the water impeller kit replacement?Thank you Charles
Expert:  Charles replied 1 year ago.

Yes I have all of your questions.

Lets focus on the carb first.

You will need to remove it. Something is not correct with the float.

The red part is a seat for the fuel primer.

The mixture needle is set at 2 1/2 turns out from a light seat.

I am enclosing an offer to get on the phone with me. We can also text with that.

Customer: replied 1 year ago.
Please call me at(###) ###-#### ***** want your service but not working on motor till Monday.Thanks
Expert:  Charles replied 1 year ago.

In order for me to see your number, you would need to accept the offer.

What time on Monday are you working on the engine? I work in a shop between 8 and 5 CST. I am available after that.

Customer: replied 1 year ago.
I am having difficulty accepting your offer from this IPhone. I cannot seem to accept your offer to discuss repair by phone for the $18 fee.I can speak with you any time Monday after 5:00 pm cst. I work from home on the motor.
Expert:  Charles replied 1 year ago.

Sounds good. You can also try and submit me the same offer, Let me see if I can accept it.

Customer: replied 1 year ago.
Charles, did you receive my offer which I resent once again @ 9:15 pm eastern?
Expert:  Charles replied 1 year ago.

I am not seeing one at all.

Customer: replied 1 year ago.
I keep "Accepting This Offer" and nothing happens on your end. I am about to give up since I have done so 3-4 times. Any suggestions as I can use your help!
Expert:  Charles replied 1 year ago.

Please give out customer service an email. Explain to them that you wish to accept the offer, maybe they can make it go thru.