1979 mercury 175

[chevyballer]

i bought a boat with a 1979 mercury 175 at idle it runs a little rough but when i wot it revs up like it should then it starts bogging 2 seconds later? it will take a while to get ok speed but not full speed?ENGINE SOUNDS LIKE ITS STRAYNING. MAYBE PROP?COMPRESSION OK.CARBS REBULIT.SPARK ALL OK I ALSO PUT A NEW TANK WITH NEW GAS BEFORE I INSTALLED REBUILT CARBS.OLD ONE NO GOOD

 

[chevyballer]

Re: 1979 mercury 175

Originally posted by chevyballer:<br /> i bought a boat with a 1979 mercury 175, at idle it runs a little rough but when i wot it revs up like it should then it starts bogging 2 seconds later. It will take a while to get ok speed but not full speed. ENGINE SOUNDS LIKE ITS STRAINING. MAYBE PROP? COMPRESSION OK. CARBS REBUIlT. SPARK ALL OK. I ALSO PUT A NEW TANK WITH NEW GAS BEFORE I INSTALLED REBUILT CARBS.OLD ONE NO GOOD

 

[andy6374]

Re: 1979 mercury 175

So you are sure you have spark on all 6 cylinders? Have you checked the fuel line and primer bulb (ie is the primer bulb firm). Try pumping the primer bulb while giving it full throttle and if this saves it from bogging out, then the fuel pump is damaged.<br /><br />When the carbs were rebuilt, did you make sure the carbs were sync'd, ie they open and close at the same rate. A poor idle (sputtering) can be caused from the throttle shutters in the carb throats not being fully closed at idle.<br /><br />You can loose a cylinder on these V6's and still have a fairly smooth idle.

 

[chevyballer]

Re: 1979 mercury 175

I tryed pumping the primer bulb and it's rock hard and no difference. I didn't do the carbs but i know he checked theim to see if they opened and closed all the way. Do you think timing is an issue? A little off timing could effect it?is there a adjust screw for these carbs? Thanks for your help.

 

[chevyballer]

Re: 1979 mercury 175

the carb were redone 2 months ago and all the carbs yes are syncd.

 

[andy6374]

Re: 1979 mercury 175

If you have spark and compression, then it must be a fuel problem somewhere.