bad running merc 650

[chipndale]

i have a real sick running 65 hp ! it will run up to 22 mph,thats it !the carbs were redone at local dealer,all new fuel parts from tank to motor,it takes a great deal of time to get up to22mph,,can you give me some sort of starting point as to what i can do to repair this problem?it seems to be getting plenty of fuel,maybe to much,are there carb. adjustments? thank for your help. A Friend posted this message and didn't tell you enough information. As far as I know the year is 1970 and it's on a 1970 Tri-hull Bayliner. The boat sat for aproximately 3 years before I bought it. It cost almost $200 for the mechanic to clean and replace one float in the carburetors. The timing wasn't checked. Also The last thing that I replaced was the fuel line connector to the motor and haven't got to check that to see if it is fixed. I read on this forum that was one guys problem. The motor will run at full throttle for awhile then shut down to an idle and die. Pumping the primer bulb will get started again, but doesn't run very good.

 

[jfholijr]

Re: bad running merc 650

forgive my question here but I have the same motor essentially, what were you charged for the shops work on your motor?

 

[fgbutler]

Re: bad running merc 650

If the carbs were recently redone I would look elsewhere first. Did the shop adjust the timing? The timing is quite a procedure so don't touch without a manual. As I understand, the spark advance is supposed to operate at a certain rpm. If too early or late you may not be getting spark at the right time and losing out on a lot of power.

 

[rockytop93]

Re: bad running merc 650

you didn't say what year the motor is, but i have a 75 650 that was giving me similar problems. I finaly found the timing belt to be off one tooth. Set it right and performed the link and sinc by the book. Runs great now

 

[dinsdale]

Re: bad running merc 650

I have a 1965 650 that runs really nice. It is on a 1964 Grew 16' Utility. I get 30 MPH at WOT and cruise nicely @ 22 MPH at around 2/3s throttle. While my boat is light, ~ 600 pounds, it is very wide and has a deep V hull. I get up on plane in about 2-3 secs with 2 people in boats and 6-7 with 4 adults and 1 child.<br /><br />Just letting you know what to expect from a good running 650.

 

[RICKRICK1]

Re: bad running merc 650

Dennis1. Get a good manual on your motor.<br /><br />Post the size, #cylinders, and serial number. And if you have it RPMs at WOT.<br /><br />You need to check compression on all cylinders, even though you had the carbs recently done it may still be a carb problem. Link and synk the throttle system as outlined for your motor. What pitch prop are you running, may be to high for the boat and weight you are pushing. Where is your trim pin installed. Are you sure the foam in the boat is not saturated (most weight can come from this).

 

[CU2NITE]

Re: bad running merc 650

Are you getting spark to all cylinders? Make sure you check for this. One cylinder without spark will cause this type of symptom. Good luck and let us know what you found out.<br />CU

 

[chipndale]

Re: bad running merc 650

Thanks for all of the info. The # of cyl's is 4. The serial # is 2605193. I was assuming that it was a 1970 model because the boat and motor were purchased together, but you know what ASSUME does. I have purchased a SELOC manual and attemped to do the Link and sync, but I will have to re-do it because I finally figured out that I have a type II ignition system. I also did a compression test and all 4 cyl's are at 100 psi. The mechanic that worked on the carburetors last year said that was low. He thought I should de-carbon the cylinders because the rings may be stuck and if that didn't help I should have the cylinders boroscoped for scaring.