1980 70 hp 3 clinyder running problems

[dbecker1]

hello i have a 80 model 3 clyinder 70 hp and cant figure out what the heck is going on. it started out it would run then all of a sudden it would bog down and wouldnt pick up rpms to run again but if i put it in reverse it would run great no problems went down to the local boat shop he sold me a fuel pump repair kit but it came with a o-ring and when i took my apart i didnt see a o-ring in it so i left it out and proceeded to rebulid the carbs go that done went to the lake and man it ran the best it ever did for about 15 minutes then back to the oringial problem again. but i did noticed that i started out with 7 gal of gas and i went threw about 3/4 of it an about 1 1/2 hours any help would be great thanks Dennis

 

[Coloradolakeboy]

Re: 1980 70 hp 3 clinyder running problems

Have you replaced the fuel lines? You could be getting air in the fuel from old lines, bad bayonet connector or the pickup tube in the tank. Put a clear vinyl hose in the fuel line and check for air bubbles. Try pumping the primer ball when it bogs, if power returns, it's likely an air leak. I would not run it until you test the fuel side. You could burn a piston from running it too lean. The O ring is for the cover for the screen filter on some pumps. It is where the fuel line goes into the pump on mine.

 

[hotrod53]

Re: 1980 70 hp 3 clinyder running problems

Sounds like you're dropping a cylinder, my 4 cylinder 500 did that. I got the motor back from a Marine Mechanic and he broke a plug wire when he pulled the plugs. Having a broken plug wire eventually results in a blown coil, the energy has to go somewhere and it goes to ground the best way it can. You may also be losing a carb if you have 2, thats not a good thing, clean it and rebuild them.

I would suggest starting by looking for burns on your coils, ohm out your plug wires, ohm out your secondary on the coil to ground, should be about 950 ohms, ohm your primary to ground, all cylinders should be about equal, check all of your coil grounds, check all of your connections to the switchbox too.

 

[dbecker1]

Re: 1980 70 hp 3 clinyder running problems

hey guys thanks for the help i will check everything you guys mentioned and get back to you. its just crazy i finally got a 55 gallon barrel to run it at home it has a jet on it w/o a flush kit so everytime i did something i had to drag it too the lake and its getting kinda old just going there and then putting it back on the trailer but i will get back to you and let you know what going on thanks Dennis

 

[ajgraz]

Re: 1980 70 hp 3 clinyder running problems

Agreed with the guy mentioning the fuel issues as the first place to look. Did you do new needles and seats in the carb maintenance?