Mercury 650 Stalls out when put into gear

[Fasha86]

I purchased a Mercury Thunderbolt 650 a few months ago and having issues with it when my boat is in the water. To be exact, the motor starts up and idles all day, but when i put it into gear forward or reverse it stalls out. When i run it on the muffs i don't experience the same issues. Now i just rebuilt the carbs, fuel pumps, and replaced the wiring harness and it still happens. All 4 cylinders have good compression and the plugs are good and good spark for each. Just to be safe i put an inline fuel filter in the mix in case there is any gunk in the tank. The serial # is 2602808 which makes it a 1969-1971. PLEASE HELP! I'm out of ideas. Thanks

 

[Home Cookin']

Re: Mercury 650 Stalls out when put into gear

I have a thunderbolt 200 that was bogging when i accelerated and it was a frayed wire shortnig agaist the block when it shifted from low speed to high speed (the top of the motor where the stators are physically moves when you advance from one stage to the other). Try it at night when you can see a spark.

 

[Fasha86]

Re: Mercury 650 Stalls out when put into gear

I'll definitely check into that, but i can't even get it from low speed to high. It completely dies seconds after putting it into gear.

 

[JB]

Re: Mercury 650 Stalls out when put into gear

Howdy, Fasha.

Welcome to iboats.

This forum is for boats, not engines (note the title).

I will move this to the Merc forum for you.

 

[Maxz695]

Re: Mercury 650 Stalls out when put into gear

If your throttle has a neutral switch which prevents it from being started in drive then it may be the cuprit. being the year I would think wear and tear may have overcome the throttle switch. Just a thought. You could try removing the throttle cable at the engine when started on muffs and then switch into fowards on the shifter bracket to see if it still runs You can also disconnect the kill wires on the switchbox. I,m not firmiliar with your some are blk and yellow some are salmon (Orange) Maybe someone here can help. If it works them the problem should be adressed and repaired as like my shifter it will start in any gear (Dangerous) Camander 2000 shifter

 

[Fasha86]

Re: Mercury 650 Stalls out when put into gear

Howdy, Fasha.

Welcome to iboats.

This forum is for boats, not engines (note the title).

I will move this to the Merc forum for you.

Thanks JB. Caught not paying attention

 

[Fasha86]

Re: Mercury 650 Stalls out when put into gear

Max,

Thats another thing i thought was odd. The killswitch wire(orange) and the tach wire(brown) were spliced together on the old harness so i did the same thing when installing the new harness. Dont know if that could cause an issue.

 

[Maxz695]

Re: Mercury 650 Stalls out when put into gear

From what I knew the tach wire is hooked to the yellow wire on the rectifier (Grey wire)I don,t see why it would be hooked to the kill switch at all except for the ground? Got me

 

[Fasha86]

Re: Mercury 650 Stalls out when put into gear

I couldnt figure that out either. I may just eliminate the tach wire all together considering i dont even utilize it. The funny thing too is looking through the service manual, i cant seem to match any of the wiring diagrams to the way it's laid out on my engine...weird. Thanks for the help all. If anyone else has any suggestions it's greatly appreciated. For now i'll go through and check the timing and throttle linkage and see what happens.

 

[mr 88]

Re: Mercury 650 Stalls out when put into gear

Open up the idle jets a 1/4 turn and see if that helps,a tach is always useful,hook it up correctly. What rpm are you idling at with the muffs on ? Should be around 1000 and when in water it will drop to 750-900.I do not think your issue is electrical.