150 Merc- Low Speed Idle problem

[fish-N]

I have a Mercury 150 hp Black Max Oil injected outboard serial #0B375554 on a 19ft boat. I just bought the boat last June. Problem is, at low speed- just off idle in gear, boat does not run good and hesitates. When going from stop to full throttle it runs great wtih no missing or hesitation. Also on start ups, when the motor is warm, the motor coughs when starting, but always starts. Thinking of cleaning carbs, if so...what carb kit do I get?

 

[andy6374]

Re: 150 Merc- Low Speed Idle problem

I would just start with a set of gaskets for each carb. You probably do not full repair kit. Just dissassemble, soak in carb cleaner (the stuff purchased by the gallon), then blown out with compressed air, and then reassembled with the new gaskets. I just did mine, 88' V6 200HP merc, and now it idles in gear at ~575-625 RPM and in neutral at ~800 RPM.<br /><br />Good luck-<br />Andy

 

[fish-N]

Re: 150 Merc- Low Speed Idle problem

Thank you for the reply. Do you think I need any other parts or just gaskets for carb? What about fuel pump rebuild? I also run my boat at sea level to 5000 ft, should I rejet carbs?

 

[andy6374]

Re: 150 Merc- Low Speed Idle problem

That whole sea level thing is a tricky issue, an issue of which I have no experience. I would try posting a separate post that addresses that issue and the real pros of this forum can give you a hand. Maybe do a search for it on this site.<br /><br />You could do a fuel pump rebuilt, it is inexpensive and easy. But I would just start with ripping off the carbs and bringing them home for a good cleaning.

 

[fish-N]

Re: 150 Merc- Low Speed Idle problem

Carb help-- I took carbs off and they look very cleen inside hope I am heading in right direction for my problem. Do I have the right jets in carbs? All three are the same .048 idle jet, .78 vent jet, .80 main jet.<br /><br />Only numbers I can find on the carbs is "WH", my book has numbers next to the WH, but my carbs don't. Other numbers on carb 1374-5427c. <br /><br />Thank you in advance for your help!