1990 90hp Johnson VRO Running Rich? You tell me!

[crane-hawk]

A few first things first. I would consider myself an intermediate mechanic but a novice when it comes to outboards (lack of experience). I don't want any discussion to take place regarding my VRO either; that debate will not be settled here.

Took my boat out a week ago. Initially started perfect and ran fine to a dock less that 10 min from the launch. Tied to dock and waited for friends. After approximately 35 min, friends showed up to go for a ride. 90hp would not start. After a ridiculous amount of cranking, it finally started but did not idle very well (would frequently die). When I took it out of neutral it would bog down. If I gave it additional throttle it would die. If I would go back to neutral it would resume a rough idle. I was able to take it out of neutral and immediately give it near full throttle and it would accelerate. This worked only a few times. Once it was up on a plane and moving at a cruising speed it seemed to be ok. When I went back to neutral I was back to square one (rough idle, wouldn't want to accelerate). Squeezing the prime bulb never seemed to help.

Once it was home I noticed oil dripping off the bottom fin of the gear case. I thought it might be a shaft seal going bad so I pulled the prop. The seal is good and it appears it is coming out the exhaust port. Pulled all the plugs and they looked moist-ish.

My novice analysis is that it is running rich. I am at a loss as to how to proceed. I think it could be one of the following: sucking air in the fuel line, fuel side of VRO going bad, bad fuel filter.

Power head and carbs were recently rebuilt (within a year or so). Kicker and main run off the same 30 gal tank. Kicker was running fine (got me to launch) so I am not suspecting anything from the fuel tank to the water seperator (were the fuel line splits for each motor).

I am on the right track? How should I proceed?

 

[Noltz]

Re: 1990 90hp Johnson VRO Running Rich? You tell me!

We've been doing a lot of investigating on my 40 lately, so I'll share what I've learned. Two strokes always will look moist/rich if you shut down at idle. The only way to read the plugs on a 2 stroke is full-throttle for a few seconds and shut it off. On a bike this is easy, outboard not so much since you need to drop it into neutral also to make sure the prop doesn't spin the engine and draw in fuel. In short, reading the plugs isn't much help. The VRO pumps do have a habit of wearing out but usually not to the rich side. Mine is leaking, thus disabled. Would you be comfortable performing a temporary VRO disable, run 40:1 and see how it works?

Have you tried running it on muffs and pulling each spark plug to gauge the engines response?

Have you tried disconnecting the throttle linkage and try cycling each carb individually (looking for very similar responses from all, either accelerating or bogging)

Personally I've found a infrared temperature gun to the best indicator of how the cylinders are working. We found one cylinder was consistently 20?F cooler than the other. A tiny change to the throttle linkage and they're dead on again.

 

[kjdunne]

Re: 1990 90hp Johnson VRO Running Rich? You tell me!

Thoroughly check the fuel lines between the tank and the 90 hp VRO fuel inlet for an air leak, use a vacuum pump and gauge if you can. It can cause the symptoms you describe without visably leaking fuel.

 

[tphaggerty]

Re: 1990 90hp Johnson VRO Running Rich? You tell me!

I recently found that one of the clamps on my fuel line (from the water separator) was loose. Tightening that up apparently stopped air from being drawn in and definitely helped smooth out the idling.

The other thing to check is that the red lever on the primer solenoid is completely down. If the lever is anything but down, it is allowing additional fuel to get to the engine. My primer solenoid went bad and I was starting the engine by turning the lever up and squeezing the fuel bulb (which works). However, I almost always forgot to return the red lever to the down position and the engine would start then die. A few times, I turned the lever down but not all the way and it idled rough and bogged on take off (presumably due to the additional fuel causing the engine to run rich).