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1980 70hp Evinrude

VickyW

New member
Bought a boat last fall with a 1980 3 cyl. 70hp Evinrude motor, 13.25x17 prop. The boat is a 14 foot fiberglass tri hull. Here's the problem. After the boat has been idling for a while, (like waiting for a skier to get ready), when you hit the throttle the engine just chuggs and dies. It does work pretty good if not towing a skier, but does also do it sometimes. Carbs have been cleaned, timing adjusted, and new plugs put in. Was wondering if this is a common problem, and how do we fix it. And could we have the wrong size prop on this boat. Can't test that as we do not have a tach on the boat either. Please help!
 
If I do a compression test on my motor, do I need to put the muffs on it, or can I just bump the starter?

To do a comp test correctly pull the kill switch. Hookup the comp gauge. Open throttle all the way. Spin motor till the gauge reads its highest. Usually will be about 5 or6 complete revolutions. Move to the next cylinder. Oh yeah have all the spark plugs pulled
 
Did the compression test, top cylinder was 125, 2 and 3 were both at 130. Now where do I go from here. Thanks for you help so far!
 
Took the boat out again today, same thing, if it idles for a while it bogs down when you hit the throttle. I am at whits end trying to figure this out!
 
Bought a boat last fall with a 1980 3 cyl. 70hp Evinrude motor, 13.25x17 prop. The boat is a 14 foot fiberglass tri hull. Here's the problem. After the boat has been idling for a while, (like waiting for a skier to get ready), when you hit the throttle the engine just chuggs and dies. It does work pretty good if not towing a skier, but does also do it sometimes. Carbs have been cleaned, timing adjusted, and new plugs put in. Was wondering if this is a common problem, and how do we fix it. And could we have the wrong size prop on this boat. Can't test that as we do not have a tach on the boat either. Please help!
. What is the situation with your water pump impeller and thermostat I'm wondering if your engine is overheating does it diesel?
 
a 13.5x15 pitch will fly out the hole, a 17 is not a ski prop unless you vent it.
the bogging down is bad idle circuit in he carbs or timing not correct. hope your running champion plugs and not ngk!!!


here is 13ft tri hull holshot with a 60hp evinrude tripe running 13.5x15 to show what it should be like.

go to you tube and type in
phill nutter prop.

I cant post link here for some reason ?
 
carbs need a good clean, then re sync.
also check jets for your elevation !!!


dont know why someone put too old delet
e, the post is not too old.
 
carbs need a good clean, then re sync.
also check jets for your elevation !!!


dont know why someone put too old delet
e, the post is not too old.
Check the date it's 7 months old OP last responded in 08/2015 I deleted my comment because the post is to old and they are gone. More than happy to teach you something again.
 
7 months old too old, are you nuts. 7 months is not too old.
3 years maybe, but 7 months you leave it on.
many people around also look for advice on this very subject, so it should be answered . and answered correctly.
 
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