70 hp yamaha help/insight

[SalmonSlayerr]

Hello, I am having problems with my 70hp yamaha. I took it out and left the dock and gradualy brought it up to full throttle she ran great for about 30 seconds the rapidly slow to about a stop. the motor did not stall. I limped backin on with it. I got home did a compression test on it. my top cylinder had 118 psi. middle had 112 and lower had 108. is that good compression? i think it is a fuel issue so i have purchased a carb rebuild kit and new fuel pump. I am currently wait for them to arrive in the mail. has anyone had similar issues and figured out what the problem was? if anyone can give me some info I would appreciate it. Thanks for your time.

 

[SalmonSlayerr]

Re: 70 hp yamaha help/insight

Hello, I am having problems with my 70hp yamaha. I took it out and left the dock and gradualy brought it up to full throttle she ran great for about 30 seconds the rapidly slow to about a stop. the motor did not stall. I limped backin on with it. I got home did a compression test on it. my top cylinder had 118 psi. middle had 112 and lower had 108. is that good compression? i think it is a fuel issue so i have purchased a carb rebuild kit and new fuel pump. I am currently wait for them to arrive in the mail. has anyone had similar issues and figured out what the problem was? if anyone can give me some info I would appreciate it. Thanks for your time.

Also it is not a spun prop.

 

[grinder67]

Re: 70 hp yamaha help/insight

I had simular problem on 93 75hp turn out to be that i had picked up plastic out of the fuel tank and it collected inside the fitting where the fuel line hooks to the tank. cleaned out fitting and runs great now. Hope this helps.

 

[1978skitender]

Re: 70 hp yamaha help/insight

I had simular problem on 93 75hp turn out to be that i had picked up plastic out of the fuel tank and it collected inside the fitting where the fuel line hooks to the tank. cleaned out fitting and runs great now. Hope this helps.

Indeed, make sure all the fuell passages are open. I had a dt at work that had a rubber thingy blocking the fuel right before the seperater.

 

[jeffersondodson561]

Re: 70 hp yamaha help/insight

Those compression results are acceptabel but not ideal, I would do a good decarb and I don't know what year, give your model number.

 

[SalmonSlayerr]

Re: 70 hp yamaha help/insight

It is a 1985 70hp yamaha model#70ETLK

Those compression results are acceptabel but not ideal, I would do a good decarb and I don't know what year, give your model number.

 

[SalmonSlayerr]

Re: 70 hp yamaha help/insight

Thanks. I have check the fuel line from the tank to the fuel water seperator and there was no apparent blockages. I should get my carb kits and new fuel pump today. I hope those will fix it. I will keep you all posted.

 

[SalmonSlayerr]

Re: 70 hp yamaha help/insight

Hello, I am having problems with my 70hp yamaha. I took it out and left the dock and gradualy brought it up to full throttle she ran great for about 30 seconds the rapidly slow to about a stop. the motor did not stall. I limped backin on with it. I got home did a compression test on it. my top cylinder had 118 psi. middle had 112 and lower had 108. is that good compression? i think it is a fuel issue so i have purchased a carb rebuild kit and new fuel pump. I am currently wait for them to arrive in the mail. has anyone had similar issues and figured out what the problem was? if anyone can give me some info I would appreciate it. Thanks for your time.

Got it fixed. rebuilt carbs,new fuel pump and new fuel hose with primer bulb. thanks everyone. Hope this will also help someone with similar issues.