115 thunderbolt bogging out

jeff9501

Cadet
Joined
Jul 23, 2010
Messages
13
hi every one I have a 1973 mercury 115 I just replaced the trigger switch with some help from here . The first time I put her in the water after replacing the switch it ran great !!! Full throttle no problem idled good after a while of blasting around it started to bog down if I backed off the throttle it would sort of straighten out . I thought maybe the gas was bad or contaminated ...I drained the integral gas tank after which I discovered that there was only about 1 gallon of gas in the boat . I thought I had discoverdd the problem (running out of fuel) .....I filled the tank with new premium fuel premix I was hoping that this would be the cure ....no such luck wher I first it full throttle it worked great but after a minute or two it started to bogg again.... the motor works great at idle trolling it just wont do full throttle ??? when it boggs out it seems to almost cut in and out sometimes like bogg out then go good then bogg out ................anyone have any ideas ??? I bought some Seafoam and am going to try that this morning ....thanks in advance Jeff
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,089
Re: 115 thunderbolt bogging out

Pump the primer bulb at speed. If it gets better, rebuild the fuel pump. If not, the carbs are likely gummed up. Clean the main strainer, in your case, you have banjo filters on top of each carb.
 

jeff9501

Cadet
Joined
Jul 23, 2010
Messages
13
Re: 115 thunderbolt bogging out

Banjo filter ?
What I do to check those
where do I get fuel pump kit and where would the number be on my pump?
What would be the max rpm on this engine ?

Thanks for all the advice .....jeff
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,089
Re: 115 thunderbolt bogging out

Jeff, The '73 motors usually had covers on the top of the carb bowls. They were removeable to expose drum or Banjo shaped fuel filters.

Those '73 motors also may have dual fuel pumps mounted on the transfer covers, or a single fuel pump mounted on the lower cowling. Go on the crowleymarine.com web site and get the part numbers. These parts are usually available at many places beside a Merc Dealer.
 
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