1980 50hp Merc idling problems

[kcc1414]

I have a 1980 50hp Mercury motor that I can't get to idle properly. I just got it out of the shop where they put a new remote control box on. The old one was hard shifting and had the same problem with going dead at idle. (also wouldn't go into reverse) The motor will idle, go into reverse, and run smooth on a hose, but not in the lake. <br />Also, when I got it home from the shop my tell tale stream starting spitting and finally stopped so I put a new impeller on. Still no pee. I've blown air through the line to check for obstructions but nothing. What else do I need to check and is there any way these problems are related? Thanks in advance.

 

[Texasmark]

Re: 1980 50hp Merc idling problems

How does it run "in the lake" other than idle?<br /><br />On my engine, the pee comes from the exhaust water jacket thru a hose to a fitting on the cowling. Do you have a similar setup and have you checked at the waterjacket end of the interconnect hose. Running a piece of wire should clean out any crud and if you got your impeller in properly and got your water line stabbed properly when you married the lower unit to the mid section, you have cooling water....don't think that year engine had a tstat.<br /><br />On "not running at the lake"sounds like fuel starvation. Need you to answer my first question to go on.<br /><br />Mark

 

[fishingdan]

Re: 1980 50hp Merc idling problems

The remote control box has very little to do with the idle. I hope they replaced that cables too since that is often the culprit for stiff shifter/throttle.<br /><br />Its all about spark, fuel and air. Unfortunately, running it on a hose doesn't tell you much about the on water performance unless you can really identify the very minor differences. For example, a classic merc 50 will run fine on the hose when it only has spark to 2 of the 4 cylinders or if fuel is flowing through only 1 carb. On the water, the symptoms show as engine won't idle, boat will not plane anymore, etc.<br /><br />Check for spark on all cylinders (a basic $6 test light can be found at any autopart retailer) first.

 

[kcc1414]

Re: 1980 50hp Merc idling problems

I forgot to mention I've put a new stator, trigger, and pack on in the last 2 months. They also claimed to clean the carbs. I had around 120 compression on all cyl. The motor ran fine as long as I had the fast idle lever raised a little, or once I got it into forward. It would even idle in forward, just not in neutral.(before the new control box) I can't check it now b/c of my overheating problem. <br /><br />As for the pee, my engine has a hose that runs up to the back of the block. Not sure on all the terminology.

 

[kcc1414]

Re: 1980 50hp Merc idling problems

Anyone?

 

[Laddies]

Re: 1980 50hp Merc idling problems

If your engine is running aright except at idle there are only 3 things that nornal cause that problem, to much pitch in the prop, idle speed or idle mixture, neither idle speed or mixture can be adjusted properly on a hose. The engine has both load and back pressure when in the water. Is your engine really getting hot or is the tell tall pluged up, try takeing the hose off the outlet fitting thats where they usally plug on that model