2000 johnson 70hp spark and gas but no power

[robaloroger]

j70plssd top cylinder has spark and compression but no power. when motor is running and I pull each plug wire the motor runs really rough on the 2 lower but the upper does not make a difference. When I turn the fuel mixture screw on the carb it does not bog down like the other 2 carbs. I swapped coils but it did not follow. I swapped wires from power pack to coils and runs on only 1 cylinder and backfired. I am not sure If I should even do that. The bottom 2 cylinder plugs were dirty but top was spotless. could it be temp sensor wire? If temp sensor shuts down cylinder would I still have spark? Could it be something not allowing gas to reach cylinder? I could not see much when I removed the carb. No frayed or melted wires.. Dont know what else to look for.. Trying to get ready for mini season in FL..

 

[Daviet]

Re: 2000 johnson 70hp spark and gas but no power

Try squirting some gas/oil mixture or fogging mixture into carb and see if it fires the top cylinder. Maybe you have a fuel problem in that carb.

 

[robaloroger]

Re: 2000 johnson 70hp spark and gas but no power

Try squirting some gas/oil mixture or fogging mixture into carb and see if it fires the top cylinder. Maybe you have a fuel problem in that carb.

I tried that a few times but had no luck. I am thinking of swapping carbs to rule that out.

 

[234rick]

Re: 2000 johnson 70hp spark and gas but no power

Try swapping power pack wires with all the plugs out using a spark tester. Be sure you test them with the throttle at idle & with the fast idle wide open & timer base fully advanced.

 

[robaloroger]

Re: 2000 johnson 70hp spark and gas but no power

Try swapping power pack wires with all the plugs out using a spark tester. Be sure you test them with the throttle at idle & with the fast idle wide open & timer base fully advanced.

got the same spark from all 3

 

[AlTn]

Re: 2000 johnson 70hp spark and gas but no power

spark is jumping 7/16" air gap?...compression is in the 100# range and each cylinder is within 10% of one another?...I'd pull the plugs, disable the spark, tape some paper over each spark plug hole, put a small hole in the paper at each spark plug hole to allow some of the compression to bleed off, and see if you're getting fuel to each cylinder...a crude test, but works,. It's possible you had a bad connection within the amphenol plug, or a bad ground connection to that upper coil, that has "healed" itself with all the taking apart and replacing activity.

 

[robaloroger]

Re: 2000 johnson 70hp spark and gas but no power

spark is jumping 7/16" air gap?...compression is in the 100# range and each cylinder is within 10% of one another?...I'd pull the plugs, disable the spark, tape some paper over each spark plug hole, put a small hole in the paper at each spark plug hole to allow some of the compression to bleed off, and see if you're getting fuel to each cylinder...a crude test, but works,. It's possible you had a bad connection within the amphenol plug, or a bad ground connection to that upper coil, that has "healed" itself with all the taking apart and replacing activity.

Should the paper get wet from gas? I am thinking there is no gas in top cylinder. The scary thing is if no gas then also no oil. Is the amphenol plug the plug from power pack to coil? I will try your test after work and post results.. Thanks for the advise..

 

[AlTn]

Re: 2000 johnson 70hp spark and gas but no power

yes to both..

 

[charles1974]

Re: 2000 johnson 70hp spark and gas but no power

bad reeds on that cylinder?

 

[robaloroger]

Re: 2000 johnson 70hp spark and gas but no power

bad reeds on that cylinder?

I was doing some research and I do have all the symptoms..Should I be able to see the reeds once I pull the carb?
Thanks