Any ideas for a motor running bad?

[jabipia]

I bought this boat from my wifes parents, it belong to her grandparents who bought it brand new in 1968. It has a merc 500 55 hp on it also a 68'. Out of the water it runs fine, but when it has a load on it, it runs terrible. It wont stay running at idle speed unless I keep pressing the choke in every couple seconds and it takes a couple minutes to build up speed and plain off. I have begun rebuilding things that I think may be the problem (carbs and fuel pump ), is there anything else that may be holding this motor back? I have also re-wired the motor.

 

[dakk1]

Re: Any ideas for a motor running bad?

I think your on the right track. If activating the choke makes it run better it's a fuel delivery issue in all likelihood.<br /><br />Dave..

 

[Nos4r2]

Re: Any ideas for a motor running bad?

Is the primer bulb hard while it's running?<br /><br />BTW the merc 500 is 50 hp not 55

 

[fishingdan]

Re: Any ideas for a motor running bad?

As Nos42 stated, I would check the fuel lines (tank to engine and under the cowling) and bulb for cracks or leaks. You could be getting air in the system. If they are old, replace them. Also check the fuel line fittings. Is the bulb firm before you start it and does it stay firm when the engine is running? Does anything leak when you pump the bulb?<br /><br />Do you have a service manual (Seloc or other)? Very much worth the money.

 

[timmathis]

Re: Any ideas for a motor running bad?

Also run a compression check. Tim