Troubled in Cincy

[rd9952]

I have a merc model 70 70 hp 1979 motor. We have rebuilt the fuel pump, carbs, has new trigger and new plugs. The timing has not been checked. It will start with a little help from starter fluild but will not stay running if you lower the throttle all the way down. It just sputters to a halt. Also when we tried it on the water it would just die out within seconds ( 5-6 ) of shifting into forward. I sprayed carb cleaner in every port I could find on the carbs. When idling at it's lowest running point it sounds like it has a little miss or something. Any help would be greatly appreciated. Thanks


Robbie

 

[MH Hawker]

Re: Troubled in Cincy

Starter fluid is very bad in a 2 stroke motor, it washes the oil off of the cylinder walls and the main bearings, that's a good was to fry a motor. The carbs need to be cleaned and the float and needle valve replaced.

 

[schematic]

Re: Troubled in Cincy

I have a merc model 70 70 hp 1979 motor. We have rebuilt the fuel pump, carbs, has new trigger and new plugs. The timing has not been checked. It will start with a little help from starter fluild but will not stay running if you lower the throttle all the way down. It just sputters to a halt. Also when we tried it on the water it would just die out within seconds ( 5-6 ) of shifting into forward. I sprayed carb cleaner in every port I could find on the carbs. When idling at it's lowest running point it sounds like it has a little miss or something. Any help would be greatly appreciated. Thanks


Robbie

Make darn sure that you have good spark to each plug. Seen several of that vintage have switch boxes failures.

 

[rd9952]

Re: Troubled in Cincy

Make darn sure that you have good spark to each plug. Seen several of that vintage have switch boxes failures.

Is there a way to test that switch box?

 

[quicktach]

Re: Troubled in Cincy

Never use starter fluid or you can wreck the engine. Disassemble and clean carbs properly. Do a link & synch afterward. Check gas filters first.

What do the plugs tell you?

NGK Spark Plugs USA
Stator OK. Checking everything around the switchbox is needed. If it all tests out ok ...by default you end up with a defective switchbox.