merc turning off after 30 seconds

swtch7

Cadet
Joined
May 2, 2007
Messages
24
Good afternoon,
Just had a quick question, my boat with a 4.3 v6 alpha 1 merc cruiser has just a bit of a problem... you can start it up (starts on first try) but after about 30 seconds of idle the RPMs drop to 0. It idles right around 650-700, and no crazy vibrations or anything. Also if you give it gas and get the rpms up to 1500 or so after that 30 seconds it will cut off again. Sometimes when you start it and run it hard right out of the idle it will run fine, i can then pull the rpms back and idle with no problems. Kinda weird... im getting a timing light tonight just to verify that but any other problems any of yall know about? any info would be great. thanks.
 

NW Redneck

Chief Petty Officer
Joined
Jul 30, 2006
Messages
643
Re: merc turning off after 30 seconds

My first thought is a sticking float or gunk in the needle/seat area. It starts and runs until the float bowl empties then dies. The float bowl slowly fills up and then it will start again. Another possibility is faulty fuel pump or restriction in the fuel line. Can you put a guage in the line after the pump and check the fuel pressure?
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: merc turning off after 30 seconds

What year 4.3L, Do you have an electric fuel pump?
 
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