1959 Johnson 5.5 Dying at High speed

[SEABEE#2]

I have been working on a Johnson 5.5 from 1959 and whenever I run it at high speed it bogs down real fast and jerks when it dies. Do not have a clue as to why this could be happening. Any clues or hints on where to start?

 

[HighTrim]

Re: 1959 Johnson 5.5 Dying at High speed

I would start by cleaing/rebuilding the carb. May be high speed circuit.

 

[SEABEE#2]

Re: 1959 Johnson 5.5 Dying at High speed

Whats the high speed circuit?

 

[HighTrim]

Re: 1959 Johnson 5.5 Dying at High speed

It is the path the fuel travels when in high speed operation.

Take the carb off, soak it in solvent or Pine Sol, wash with hot soapy water, blast with compressed air, then shoot aerosol carb cleaner into all passages/cavities, wash again, then blast dry with comrpessed air. Should now be spotless, time to rebuild.

Float needle could be sticking, float issue, clogged passage, etc...

Are you running on a fuel pump or pressure tank>>?

 

[SEABEE#2]

Re: 1959 Johnson 5.5 Dying at High speed

I converted it to run on a fuel pump which when I plugged one of the holes behind the carb I may not have done it right. Heres the site where I learned to convert these things. I converted my 10hp with no problem but maybe I didn't do something right there now that I think about it. 5.5 HP Evinrude Johnson Pressurized Fuel Tanks

 

[lindy46]

Re: 1959 Johnson 5.5 Dying at High speed

Did it run OK before the fuel pump conversion?

 

[Crosbyman]

Re: 1959 Johnson 5.5 Dying at High speed

In doubt, just plug up the pressure nipple with a piece of 1 inch fuel line and a fat screw and silicone. or plug it with JBweld

 

[nwcove]

Re: 1959 Johnson 5.5 Dying at High speed

In doubt, just plug up the pressure nipple with a piece of 1 inch fuel line and a fat screw and silicone. or plug it with JBweld

That wont work with the 5.5. The nipple on the intake manifold is the only place to get a pulse for the fuel pump.

 

[F_R]

Re: 1959 Johnson 5.5 Dying at High speed

Does it seem like it is tightening up when it dies? Broken shock absorber in lower unit. Very Common

---OR--can we assume it is pumping water and not overheating?

 

[Crosbyman]

Re: 1959 Johnson 5.5 Dying at High speed

good point i have been doing qd, fd, and a fleetwin 7.5 :-(

 

[SEABEE#2]

Re: 1959 Johnson 5.5 Dying at High speed

Yes it seems that way. The complete motor does a big Jerk when at the end and it feels like its tightening up. I just changed the water pump because when I ran it the first time it pumped no water whatsoever. Is the shock absorber a spring? Where can I locate the shock absorber? Thanks!

 

[HighTrim]

Re: 1959 Johnson 5.5 Dying at High speed

It is underneath the water pump housing. They should measure 6 3/4" from end to end, any more and they are no good. You will notice wear on the bearing housing plate on top of it.

 

[nwcove]

Re: 1959 Johnson 5.5 Dying at High speed

HOW TO CONVERT 50s motors from two line tanks - YouTube

jmo, but i'd look into the carb/fuel delivery first, and be as sure as possible that your conversion is ok and supplying enough fuel for wot operation. ( i would avoid the first option of filling the channel in the video)

 

[SEABEE#2]

Re: 1959 Johnson 5.5 Dying at High speed

Ok sounds good! I probably wont have time until the weekend to mess with it but your input and information is greatly appreciated! Thanks! Ill do an update when I get the chance.