1966 Merc 650 dies in gear

[wichitamichael]

I have read several posts on this topic on iboats.com. It would appear that the most common issues are:

1- Fuel pump bladders / gaskets should be replaced
2- Carburetors should be rebuilt
3- Fuel mixture is too lean
4- Idle is set too low
5- Compression is too low

I have done 1 & 2 I am going to do 3 tomorrow and I would like to do 4 tomorrow as well, but how do I tell what my idle speed actually is? The manual says that it should be set at 550 - 600 RPM at idle under load and I don't know how to measure that.

To be clear, my issue is: motor starts / runs fine out of the water but IN the water it dies immediately under load. If I trim the motor up until the prop is barely above water it will idle but not in gear. If the prop is all the way down it only starts if choked and will not stay running for more than a minute at idle and dies within a few seconds of being put into gear. Occasionally, if I rev the manual idle (not sure if that is what it is, small arm on the right side of the gear lever) and put it into gear the motor will lurch forward start to get going and then sputter out again. One time it made it up on plane and really got moving but as soon as I slowed down it died again.

Any help would be appreciated. Can't find a mechanic in Wichita that is willing to look at it.

Michael

 

[wichitamichael]

Re: 1966 Merc 650 dies in gear

Friendly bump!

 

[Fuzzytbay]

Re: 1966 Merc 650 dies in gear

Friendly bump!

Friendly answer...
Start reading here: http://forums.iboats.com/showthread.php?t=168855

Read this too, just pick your motor out of the menu:
http://www.maxrules.com/timingindex.html
Then once read you can decide where to start. My bet is on a lync n sync first. Then on to the fuel system. Least the lync n sync doesn't cost any money on parts, and once done, if it still don't run, then you can start troubleshooting it.

 

[wichitamichael]

Re: 1966 Merc 650 dies in gear

Thank you very much for your reply. I have a manual that walks me through the same procedure. My question specifically is: The manual says that the idle on my motor should be set at 550 - 600 RPM at idle under load and I don't know how to measure that. What instrument is used to measure RPM's?

 

[CV16]

Re: 1966 Merc 650 dies in gear

I would use a tachometer to measure rpm's.

 

[Fuzzytbay]

Re: 1966 Merc 650 dies in gear

You must set the low idle speed while the boat is in the water, moving in gear. That is how you load it. Don't worry about the rpms, just set it idle as low a speed as you can. It not a new motor, if you can get it to idle, low enough, that it doesn't grind shifting gears, that will be perfect.

 

[wichitamichael]

Re: 1966 Merc 650 dies in gear

Well, that is what I am trying to do, however, when I put it in gear, it dies before I get ANY noticeable movement.

 

[wichitamichael]

Re: 1966 Merc 650 dies in gear

I would use a tachometer to measure rpm's.

Do you know if there is a tachometer that can be used that is not mounted / installed? The boat did not come with one.

 

[Fuzzytbay]

Re: 1966 Merc 650 dies in gear

Well, that is what I am trying to do, however, when I put it in gear, it dies before I get ANY noticeable movement.

Did you read, the iboats post on how to do a link and sync?

You cannot short cut setting up these types of motors. RPMS are not relevent,in getting it to move on the water. Its the proper low speed idle mix. The rpms are mentioned simply to stop youf from tearing up the lower end gears. If the rpms are to high, the bottom end grinds gears when shifting,damaging them. So follow the link and sync post. When it gets to the idle speed setting, just get the motor to idle as slow as you can, by ear, trust me, you will know if the idle is too high, ie over 700 rpm. Once done, do the rest of the link and sync. It will tell you how to fix the stalling when you put it in gear, once the idle speed is set.

 

[wichitamichael]

Re: 1966 Merc 650 dies in gear

Did you read, the iboats post on how to do a link and sync?

You cannot short cut setting up these types of motors. RPMS are not relevent,in getting it to move on the water. Its the proper low speed idle mix. The rpms are mentioned simply to stop youf from tearing up the lower end gears. If the rpms are to high, the bottom end grinds gears when shifting,damaging them. So follow the link and sync post. When it gets to the idle speed setting, just get the motor to idle as slow as you can, by ear, trust me, you will know if the idle is too high, ie over 700 rpm. Once done, do the rest of the link and sync. It will tell you how to fix the stalling when you put it in gear, once the idle speed is set.

Ok-- got the fuel pumps rebuilt and NOW the engine starts but only runs for a minute or two then dies. Won't start again until I pump the bulb between the tank and engine and then it starts runs, dies and repeat.

Going to try the link and sync now and go from there.

 

[Fuzzytbay]

Re: 1966 Merc 650 dies in gear

Don't worry about getting the timing done yet. Use the info on how to set the idle speed etc. Unless someone laid out the flywheel there will be no markings on it for a timing light. So to set the timing you will need a dial indicator.