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70hp Johnson 2000 model

andos

New member
"Hi there, I have a re occurin

"Hi there, I have a re occuring problem with a 2000 70hp Johnson. Three mechanics have looked at the motor and have been unable to diagnose the problem.

Here it is. The motor will start and run beautifully from a cold start. I will drive the boat for 25 mins and then turn it off. I will leave the motor off for 15 - 25 mins and then turn the key. The motor will idle in neutral and then drop out. It can't keep the revs and when I try to get the motor into gear it will also drop out unless I can get it over 1500 - 1700rpm.

Here are the parts that have been replaced by mechanics who have thought they diagnosed the problem and stuffed up!

1. Powerpack
2. trigger and stater
3. bottom cylinder solinode

Can anyone let me know if they have experienced a similar problem?

The current mechanic has not given up and has (in his opinion) narrowed it down to an electrical problem and is going to test a new throttle box with my motor running direct with no other electrics. Does this sound right?

FYI - compression on all cyclinders is 135psi. The motor is in immaculate condition apart from this issue. To get the motor into gear on a WARM START ONLY is to tilt the motor to reduce the load back pressure and the motor will shack and sound sick before taking off over 2000rpm where the boat will then become ok again. Note the issues are only in neutral and low revs ONLY.

As you can probably tell I am extremelly frustrated and ready to trade this motor for a new 4 stroke if the issue cannot resolved in the very near future.

Thanks in advance

Andy"
 
"have u tried pushing the chok

"have u tried pushing the choke when it does that,..sounds like its real cold natured to me,..i would def go into carbs,..if all's well,..a slight rejetting may help,but is a last resort,u dont want to mask,an on-going prob.also,u may have an air leak,bad ck valves in primer bulb,...etc,allowing ur fuel to syphon back,to tank,....causing ur stumbling...ign sys needs to be checked,the second this occurs...as well as pushing the choke and squeezing primer bulb,to help identify,the prob.Engine temp,needs to be checked."
 
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