77 johnson 6hp starting issues

[pugerz]

thanks for your help in advance. I bought this motor off a buddy few years back, he said it needed a fuel pump. I discovered a crack in the fuel pump cover and it was leaking gas so I just replaced that, hoping that was all it needed. but it still wont start. I checked the compression and the readings were 92 and 82. Im not sure about replacing the fuel pump till i know its the reason for the problem. Is there an easy way to check the fuel pump out to see if its working? buddy said he had two identical motors and sold the other with the good fuel pump on it and he could get this one started when he put the good fuel pump on this motor. I only paid 75 dollars for the motor and i have a boat now i want to put it on. i did spray some fogging oil in cylinders and got a back fire first pull nothing after. thanks for your help. model 6r77m is the motor.

 

[JB]

Re: 77 johnson 6hp starting issues

Top of this Forum, Top Secret File. Do "Outboard won't start". Let us know what you find..

 

[pugerz]

Re: 77 johnson 6hp starting issues

Well i have ruled out the ignition cuz I am getting spark on the plugs. Guess i will try to start tomorrow with spraying fuel mixture into the carborator and see what happens. Do the compression results of 92 and 82 on a manual pull start motor seem ok? Starting to think its the fuel pump.

 

[jay_merrill]

Re: 77 johnson 6hp starting issues

Both are OK, but the difference between the two is a little high. Generally, you want no more than 10% differential. Your not way out of the desired range, but you are above it.

Before you worry too much, though, I would try another compression test, using another guage.



???

 

[pugerz]

Re: 77 johnson 6hp starting issues

My understanding on compression results is that they can vary with cold vs. hot motors, tester, etc. The result spread is considered bad if you exceed 15% on some motors 10 on others. The tester i used is brand new, used only few times. That lower reading was on a cylinder that showed the most crude on the spark plug tho. I dont think that is the reason why it wont start, but could be wrong on that, as well as all of the above. If the motor does have a cylinder not in best of shape, wouldnt it just reduce your performance out of the motor?