no gas top cylinder 73 Mercury 650

[mwbaughan]

I rebuilt the two carbs today. It Starts right up with dry plugs. After a couple of minutes it cuts off - top plug dry - other two plugs have gas and oil on them?????? mwbaughan@worldnet.att.net

 

[mwbaughan]

Re: no gas top cylinder 73 Mercury 650

also, the trottle arm is opening the plates but not advancing the distributor, i opened up the arm and thought i put the spring in right - but maybe not since it is not pushing the distributor arm forward

 

[joblo33]

Re: no gas top cylinder 73 Mercury 650

What was the reason for rebuilding the carbs? Does this problem predate carb work or is it only since doing the rebuilds?<br />Eric

 

[mwbaughan]

Re: no gas top cylinder 73 Mercury 650

I rebuilt the carbs becuase of the same symptoms mentioned earlier (little to no fuel to top cylinder).<br />It is getting plenty of gas to both carbs - good fuel pressure - but not evenly distributing fuel in the crankcase. I checked compression and all are 120-127 psi - the lowest being that top cylinder. I suspect stuck reeds but have never worked on these. I just ordered two sets off ebay. The spring must be sprung in my throttle lever - I recently set the motor up in the boat while I replaced the transom without unhooking the linkage - perhaps this sprung it somehow.

 

[joblo33]

Re: no gas top cylinder 73 Mercury 650

Ya, sounds like reeds to me. You can see them through the hole when you remove the carb. You need to pull the powerhead and remove the crank to access them. You might be able to clean them up through the hole behind the carb. I haven't tried because I always have the powerhead off for other reasons when I see the reeds.<br />Eric