'94 Johnson oil/fuel system

bkToad

Recruit
Joined
Dec 1, 2015
Messages
1
1994 Johnson Venom 200hp

Symptoms:
Puddle of oil drips from cowling down the shaft and settles on the floor a day after use
Excessive smoke especially at initial warmup idle, but generally excessive smoke all the time
WOT RPM under 5k
Will die out occasionally at idle and almost always when loading the boat on the trailer after letting off throttle
Sluggish holeshot and takes increasingly longer to get to WOT
Always runs and have never died out or surged at WOT. Just idles a bit rough. Boat is on the water at least once a week 9 months out of the year, but typically on no wake lakes.


The oil puddle: I have been dealing with this issue for the last couple years and had a mech tell me possibly have to replace all fuel/vaccuum lines under the cowling, and I would replace all lines from fuel and oil tank while I am at it too (lines before the motor are for sure due to be replaced). I have seen a seep (very small glisten) of oil from all or most of the vaccuum hoses all over the motor and assume this is where my puddle comes from.

It is my understanding that air getting into compromised fuel lines will cause my VRO to see the air as fuel and way over-oil my fuel. I am for-sure going to replace fuel lines between tanks and motor as they are getting weathered.


Questions:
Do I simply replace the lines leading up to the motor and see if that remedies the situation?
Do I do the above AND replace all vaccuum lines?
Do I replace the lines to the motor and test the vaccuum lines? and if so, how?
I considered servicing the carbs along with the above, but I kinda think (hope?) fixing the fuel lines will make that unnecessary

Thanks for looking.
Tim
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
Do them all as if a few are gone the others are often not far behind or have a small hard to detect leak already. Hose comes in metre lengths normally so you wont really be spending much more. Try not to use those plastic tie straps if possible,use the metal ring clips as they give a much better grip where as th etie straps have a weak point at the join where gas can leak through or air in.
Get it done though as air into a motor is often what finishes them off, you may of got lucky here and had the symptom of too much oil instead of running lean.
If you dont mind premixing thats a safer option
 

flyingscott

Fleet Admiral
Joined
Apr 8, 2014
Messages
7,985
Sorry i did not see oil tank in the original post. Yes replace all lines use oetiker clamps on the hoses.
 

fhhuber

Lieutenant
Joined
Jun 19, 2014
Messages
1,365
Its never really a bad idea to replace 20+ yr old fuel lines...

When I moved my 1990 Johnson to a different hull I had all new fuel lines put in.

************

A caution about the VRO.... I've seen a few engines trashed recently because the VRO failed and the alarm goes off just in time for it to throw a rod as you try to shut down. (this is how i got the replacement for my old hull that was going bad... someone blew up their engine when the VRO failed) The old VRO pumps from the early 90's are dieing.

If your pump is failing its far cheaper to replace with a different one that doesn't inject oil and do pre-mix. Since you have leaks in that area, I'd get the pump tested. Check the pump casing for cracking.

And remember that these are getting brittle with age and its easy to break the pump while changing the hoses.
 
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