3.0 liter Merc that stumbles on hard acceleration

[Max Spiek]

My '89 130 hp 3.0 liter Alpha 1 Mercruiser I/O stumbles when I accelerate hard. This usually occurs when the engine is warm and under load.<br /><br />I changed the accelerator pump once and it seemed to solve the problem for a couple of days only. Subsequently the carb was re-built but the problem persists. <br /><br />The carb is a 2 barrel with these markings; 138-99562 and then another number; 7303. I think it's a Rochester.<br /><br />The engine is timed to spec and I have a good spark.<br /><br />Can anybody help before I let the guy at the marina sell me a new carb?<br /><br />Max

 

[port jeff boater]

Re: 3.0 liter Merc that stumbles on hard acceleration

had the same problem with my 140 merc max.. dont know what the problems were but these were the things i did, i replaced the carb filter and fuel pump filter and changed the water separator. also changed my plugs and fuel hose, then cleaned the flame arrestor and also had to replace the intake vent hose to the engine which brings the air into the engine compartment from the starboard side,, there is also a plastic box behind the vent grill that has the two hoses connected to it,, make sure that that is snug against the fiberglass of the boat,. mine was not and the engine compartment was not getting the air it should have,, took her out yesterday after all these repairs and she ran like a top.. hope this ll works for you,,