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Ask Dominick Your Own Question
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I have a 70s evinrude triumph 70hp outboard that seems to only

Customer Question

I have a 70s evinrude triumph 70hp outboard that seems to only want to get to about 1/3-1/2 power with wot. It idles fine and sounds ok but doesn't "go". I've made sure the gas is getting to then engine but am not sure where to go from there.
Submitted: 2 years ago.
Category: Boat
Expert:  Tan replied 2 years ago.
Hello. My name is***** will be assisting you today. We need to start with a spark and compression test. The spark must jump a 7/16" gap on a spark gap tester. The compression must be 100+ psi with no more than 15% difference between cylinders. Now if you have lost spark on one cylinder the engine will not perform. If you have low or no compression on one or more cylinders the engine will not perform. Now there are a couple of tests you can do while engine is running. Run the engine up to the highest rpms it will run. Now push in on the key choking the engine does it run better? If no change squeeze the primer bulb. Does the engine run better. Ok all these tests will test the spark, compression and fuel. These are all the component that makee the engine run correctly. Post back with findings and questions.
Customer: replied 2 years ago.
Squeezing the bulb doesn't affect the motor. The choke has no effect that I can notice. If the choke had made a difference (this engine has an on off and auto position on the engine itself) what would that have possibly meant ?
Expert:  Tan replied 2 years ago.
The choke being activated when the engine is acting up would improve the performance if you had a carburetor issue. Now if the choke was on the engine would not stay running and auto choke only means the choke works when the key is pushed activating the choke solenoid. There is one more test which the primer bulb should have eliminated. This is run the engine on another fuel tank just to be sure we don't have a fuel restriction. Since no change with the choke or the primer bulb that leaves compression or spark. The next step is the spark and compression test.
Customer: replied 2 years ago.
I do have an extra tank so I will hook that up and try that. I'll get new spark plugs as well.
Does the little toggle below the ignition have any effect? I was told to hold it up while turning the key but have never had a boat with one of those.
If neither of those resolve the issue I'll get what I need to check compression.
Expert:  Tan replied 2 years ago.
Ok. That is the choke switch. When you are running the boat lift that switch when the engine is acting up. Post back with findings.
Customer: replied 2 years ago.
No difference with either the other tank or the choke. The motor doesn't act up it just doesn't go.
Expert:  Tan replied 2 years ago.
Are you doing these tests with the boat in the water under load? These tests won't work on a flush attachment. When I say when the motor is acting up I mean where it has no more power. Another words put the engine in gear and run it up as fast as it will go then lift the choke switch. Does the engine run any better? If no change run the boat up as fast as it will go and squeeze the primer bulb. Does it run any better?
Customer: replied 2 years ago.
It is in the water and had no effect. I did find this dangling when I took the cover off...
Expert:  Tan replied 2 years ago.
Sorry i had to step out. Ok that is the choke plunger. That goes in to the solenoid. The plunger goes in where the red circle is in the pic below..
Customer: replied 2 years ago.
I'll try tomorrow. Thanks
Expert:  Tan replied 2 years ago.
Ok post back when you have done those checks. We know the choke test didn't work as the choke was not working. The plunger in the solenoid is what closes the choke. This will eliminate the carbs as a possible cause of the poor running. If the choke doesn't do anything then we need to do the spark and compression tests.