Mercury Classic 50 fuel problems

[abrown1434]

Hello, I have a 1986 mercury 45hp classic 50 engine. I recently went through the engine because it set a number of years. I found some electrical issues which I ended up replacing the crank trigger, stator, and rectifier due to burnt wiring. I have also rebuilt the carbs fully. Now the engine runs smooth as ever but I am having a surging issue which I know is fuel related because it will not surge as long as the bulb is massaged every minute or so. Fuel lines are new, bulb is new, all fittings are new. Now my question, before I tear back into the carburetors what is the chance the problem is with the auto blend remote oil unit. I removed the auto blend before I got the engine running again so it's a possible changing point. I know the auto blend has a diaphragm style pump in it which is operated by vacuum. Could it be possible that this unit kept the engine fed and now is causing the surge issue? I removed it because of the horror stories I've read about. Thanks in advance. Aaron

 

[carholme]

Re: Mercury Classic 50 fuel problems

Aaron;

If pumping the bulb corrects the surging problem, why not keep it simple and rebuild the fuel pump first.

Gerry

 

[abrown1434]

Re: Mercury Classic 50 fuel problems

Aaron;

If pumping the bulb corrects the surging problem, why not keep it simple and rebuild the fuel pump first.

Gerry

Gerry,
Thansk for your reply, I do agree it's easy to rebuild the pumps (Walbro carbs) pumps on side of carbs. They do have new diaphrams in the pumps but that doesn't mean they are good. The only other change point I could think of was the oiler in which I would hate to reinstall it just becuase of the potential problems with the units.

Thanks again.

 

[abrown1434]

Re: Mercury Classic 50 fuel problems

Gerry,
Thansk for your reply, I do agree it's easy to rebuild the pumps (Walbro carbs) pumps on side of carbs. They do have new diaphrams in the pumps but that doesn't mean they are good. The only other change point I could think of was the oiler in which I would hate to reinstall it just becuase of the potential problems with the units.

Thanks again.

Quick Update:
rebuilt fuel pumps again also reset float height. Resting float height with carb inverted was in spec, bottom drop distance referenced from float to high speed needle was way off. Engine runs like a champ now.