Mariner 70hp 82model, only starts on 1/4 throttle

[marine11]

I have just purchased a mariner 70hp 82model, motor, it only starts if you pump the throttle up to 1/4, as soon as you drop throttle back to idle it cuts out, then i have to start it again.

also i check the spark plugs and noticed the 2 top ones are black, and the bottom one is is like new, and very clean, what does this mean.

also is this motor a 2 stroke or a 4 stroke.

thank you in advance for you help

 

[Dave1027]

Re: Mariner 70hp 82model, only starts on 1/4 throttle

Do a compression test.
Do a sync and link.
2 stroke.
You are mixing TCW3 oil with the gas I hope!

 

[marine11]

Re: Mariner 70hp 82model, only starts on 1/4 throttle

I have done the compression test, all cylinders are 120, give or take 1-2points.

what is a sync and link, and i have bought this motor 2nd hand so i dont know what oil has been in it.

I will use that from now on.

 

[Dave1027]

Re: Mariner 70hp 82model, only starts on 1/4 throttle

A sync and link is the timing and adjustment procedure. It is different for every motor so I can't give you a step by step. Search or buy the service manual. The library might even have it.

If you don't mix TCW3 oil with the gas at a 50:1 ratio you will ruin the motor.

 

[James R]

Re: Mariner 70hp 82model, only starts on 1/4 throttle

If you have no service history on this motor the carbs are suspect. They will need removing, stripping, cleaning and rebuilding with new kits. Don't use spray carb cleaner. One, it wont clean the carbs and two, it can do damage. There is only one way, the correct way. Use Gunk carb and Parts cleaner. It will do a good job and no damage even to plastic parts.