1978 Johnson 70HP

[txwildhorse]

I have a 1978 Johnson 70HP outboard motor on a 1973 Del Magic boat, My problem is that if I put the muffs on the motor it will run fine go into gear great and rev up just fin, But when I have it in the water under a load it will die when I try and put it in gear. I can not figure out why it is doing this. Does anyone have any ideas as to what I need to do to fix this issue

 

[Joe Reeves]

Re: 1978 Johnson 70HP

What kind of compression and spark do you have? If normal, in all probability, you have fouled carburetors that need cleaning.

 

[txwildhorse]

Re: 1978 Johnson 70HP

well within the last 5 months it has been at Lake Park Marina, and they were supposed to have put Carb Kits in it

 

[Chinewalker]

Re: 1978 Johnson 70HP

Definitely not getting power from all three cylinders - running on muffs can be very deceiving. I concur with Joe - sounds like fuel issue, but check for spark in all three cylinders, too.
Also, NEVER rev up the motor out of the water. Doesn't take much for them to run away and toss a rod.

 

[tashasdaddy]

Re: 1978 Johnson 70HP

what are your idle rpms, in the water, you idle speed may be set too low. it will run fine on muffs, and not in the water, on muffs there is no back pressure, on the exhaust, which there is in the water. you idle speed stop screw must be set in the water and with the motor in gear. you can set the idle faster on muffs, then fine tune it in the water.