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2005 Johnson 90 (2 stroke) will idle but not run after it sits.

S

Sonix

New member
Greetings,

So my J90PLSOA Engine has been giving me a run for my moneythe last few years. First start is always a little tough (its a two stroke whatdo you want from it?). After the second or third key turn it idles like achamp. I can run it as long as i want with no issues its turning perfect RPMand sounds great. After i turn it off for any amount of time it will start backup and idle but when i put it into gear it dies. It will re-start and i canthrottle it up with the leaver but once again as soon as i put it in gear itjust stops. This will eventually lead to not wanting to start at all or a deadbattery. If it sits for a few hours it starts up and runs like nothing everhappened.

I believe i'm suffering from heat sink and something is upwith the vapor pump possibly so i bought the Seloc #1314 Manual and it does notseem to have the best information and diagrams on the 2 stroke engines. Ittalks about heat sink and says i should install clear lines (which i plan ondoing) but it doesn't have any indication of what to do if that is your issue.Also i see no mention or diagrams of my version of the vapor pump, I wanted torebuild the system but i want to order all the parts for the job before i takeit apart. Marineengine.com seems to have a proper diagram of my engine and thevapor pump but even still its not a kit so i need to know each piece that iwill need to do the job properly.

If anybody else has beat heat sink i'm open to all ideas evenafter i get this rebuild done. (i was thinking about mounting a fan in theresomehow like a car to move the air when i turn the boat off) I also saw sometalk about adding an electronic fuel pump to the system but i can't get a clearidea on how that's done in a 2 stroke environment.

I attached pictures of the parts in question any help wouldbe great.

Cheers,
Joe


 

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Motors in good condition start right up with the proper start procedure.----Post the results of a compression test.----Repair kit is available for the vapour pump.
 
My dad and my mechanic checked my compression and both said it was in spec. I don't have the tool available to me but as soon as i can borrow one i will run a comp check again it might just take me some time.

I took the entire assembly off today and i'm going to look for rebuild everything on it but the VRO - I don't think its having fuel pump issues because i can run the boat for hours at perfect 5300 RPM and it sounds great its just that possible heat sink that's killing me.

I'm also going to get some automotive heat shielding and try to fit it between the plate that holds this up and the block to try to get a bit of the direct heat off the plastic bowl/pump in case that is causing air bubbles in the system.
 
Hey Teg,

Funny you say that i just went on amazon last night and ordered myself a decent vacuum pump tester and cylinder compression tool they are both long overdue in my toolbox.

They are due to arrive on Monday so shortly there after i can get my compression posted.

When you say "test the pump" what specific part are you referring to? I have the book so i should be able to look up flow specs.

Thanks!
 
Hey Teg,

Funny you say that i just went on amazon last night and ordered myself a decent vacuum pump tester and cylinder compression tool they are both long overdue in my toolbox.

They are due to arrive on Monday so shortly there after i can get my compression posted.

When you say "test the pump" what specific part are you referring to? I have the book so i should be able to look up flow specs.

Thanks!
 
?----Vacuum pump ?-----The VRO operates with a positive pressure pulse and a slight negative pulse.----Not sure how you would test it with a " vacuum pump "
 
A faulty diaframe will cause problems , wot you can do is get a piece of clear hose cut it in half and fit a T-piece between the 2 halfs one end connect it to the vro inlet the other end to the fuel line then on the other end of the T-piece connect a vacuum gauge start the motor and observ for air bubbels in the clear hose and keep an eye on the vacuum gauge if it reads 4 and above you have a vacuum restriction at WOT you should get a reading between 2.5 and 3 if you see air bubbels your fuel lines are sucking air. if all this checks out good we move to the next steps .
 
Hey racerone,

As requested here is the compression test results. I wish i had cylinder numbers but this Seloc book has all but forsaken my poor engine. I'm not sure what the spec is yet i'm still digging through this book. Looking back i may have done this wrong i did one cylinder at a time and i didn't remove all the plugs. I will re-test again tomorrow because i'm not sure what not taking all the plugs out may change.

Starboard top - 121
Starboard bottom - 124
Port top - 113
Port bottom - 120


Teg,

Its going to take me a while to get it up and running it sat for a while so i'm draining the fuel system and rebuilding the vapor pump/solenoid while i have it all apart.
 
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