johnson 90 vro carbs

goonski

Recruit
Joined
Jul 25, 2009
Messages
5
Hi, I got a Johnson vro 90 hp on my boat, it boggs hard off the start and won't go to full power until trimmed out, or what I think is full power. I just bought this boat and this is the last bug to iron out. The model number of the engine is CJ90TLCDC, I have pulled plugs and all seem to be running lean exept on on the bottom right, drivers side, that plug is always wet with gas. My question is I could not find any adjusting scews on the carb, are there any? Do these carbs need rebuilding or is there a bigger issue? Are there any reeds in these engines? When the plastic cover is off and engine is idling, I have gas mist coming out of the left bottom carb port, which is why I'm asking about reeds. I have a service manuel on order but has not showed up yet. Also, what plugs do you recommend for this motor, I'm not sure if I have the right ones in it but I have NGK BR7HS in it now. Any help would be greatly appreciated!
 

petryshyn

Commander
Joined
Oct 3, 2001
Messages
2,851
Re: johnson 90 vro carbs

QL77JC4 is the plug.
No external Adjustments on the carbs.
Do a compression test. I just finished a 90hp with 0 compression on #3.
Hope you have better luck....

I'm at Moose lake by Bonnyville.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: johnson 90 vro carbs

i agree start at the beginning. compression and spark test on all cylinders. spark jump 7/16 inch, compression 100 psi or more, but must be within 10% of each other.

99% the carbs need cleaning, removing all jets rebuild kit. http://forums.iboats.com/showthread.php?t=299680
 

goonski

Recruit
Joined
Jul 25, 2009
Messages
5
Re: johnson 90 vro carbs

Thanks for the info, it has excellent spark but I didn't do a compressoin test but it seems to idle ok. I also going to try cleaning the carbs and put kits in as well, if the compression checks out. I'll let you know how it goes!
 

kenmyfam

Supreme Mariner
Joined
Aug 10, 2006
Messages
14,385
Re: johnson 90 vro carbs

Dump the NGK plugs and use champions.
 

goonski

Recruit
Joined
Jul 25, 2009
Messages
5
Re: johnson 90 vro carbs

JUst finished compression test on the engine and the 2 port side were 135 psi and the 2 starboard were 140 psi, which tells me all is good there. I guess the next step is to clean carbs and install kits. Should I try running some carb cleaner down the throats when it is running, will this help? Thanks in advance!
 

petryshyn

Commander
Joined
Oct 3, 2001
Messages
2,851
Re: johnson 90 vro carbs

Don't do it. Its too dry. Go and get some decarb from your local dealer (Hillside, Frasers, Bumper 2 Bumper, Lakeshore Marine) Pull the plugs and give each cylinder a good drink, then let it sit for a few hours (while your doing the carbs)
 

goonski

Recruit
Joined
Jul 25, 2009
Messages
5
Re: johnson 90 vro carbs

Thanks, I goota go to hillside and get the kits, Thanks for the help!
 
Top