'97 90 SPL VRO too much oil

[kjdunne]

J90TSLEU, it seems the VRO is mixing way too much oil into the fuel. I first had trouble after running at cruise for 20 mins. then idling in neutral, it stalled after a minute or 2. It was hard to start, but by bumping the primer quickly with the high idle lever about half way up it started and ran rough like it had a fouled plug or 2. I put it in gear and was able to get it cleared out after a little running. It seemed to run OK at cruise, but I have a 5+ min. no wake zone to get back to the launch ramp. I noticed it was putting out a lot of white exhaust smoke after a couple of minutes of running at slow speed. It stalled again and was real hard to start, again using the primer and high idle lever, I think it needed to dilute the oil rich fuel.

Back at home on the earmuffs it ran, but was putting out real thick white exhaust smoke and a lot of exhaust oil residue drained out after I turned it off.

The spark plugs were fuel and oil wet, not really fouled up, with the center insulators light tan as they should be in a good running engine.

Has anybody had a similar problem with the VRO seeming to mix too much oil? I know lots of guys have had them mix too little or none at all. Is this a simple fix to the VRO system, or is a new pump required? Of course I could go the bypass and pre-mix route as an option.

I thought maybe it was starving for gas causing the oil rich mixture, but she runs fine at all RPM otherwise until it gets oil fouled at low RPM.

Thanks in advance for your help and advice.

 

[Daviet]

Re: '97 90 SPL VRO too much oil

Is this engine new to you, have you had this problem for awhile or did it just start?
I question the white smoke, have you checked the compression?

 

[kjdunne]

Re: '97 90 SPL VRO too much oil

I've had the engine 2 seasons now. The problem just started, the engine is (was) a very good runner. I'll check compression tomorrow, was in the 120-130 range all around last season.

The smoke is definately 2 stroke oil smoke.

 

[schematic]

Re: '97 90 SPL VRO too much oil

The only way the OMS pump can over oil is by a failure in the fuel side (either inlet or outlet check valves or diaphram failure) or an air leak or fuel restriction in the fuel supply. If a check valve leaks, the air motor of the pump will work overtime trying to pump fuel. The extra strokes it makes will result in extra oil.

 

[Chris1956]

Re: '97 90 SPL VRO too much oil

White smoke is usually steam. Too much steam would indicate a water leak into the cylinder. Pul the spark plugs and see if any are real clean (steamcleaned). If so, it points to a water leak.

 

[kjdunne]

Re: '97 90 SPL VRO too much oil

Thanks for the quick replies. Compression test today, #1= 135, #2= 130, #3= 130, #4= 125, no problem there. The smoke is really light grey, it looks like I'm giving it a heavy dose of fogging oil thru the carbs. Just wanted to say it's not black or dark. No sign of water on the plugs or piston tops that I can see thru plug holes. The spark plugs look good considering the way it's running. I'm going to check for air leaks as soon as I can get vacuum / pressure guages, any suggestions on a vacuum / pressure pump that's reasonable? I'm thinking along the line of a bad fuel side pump diaphragm may be the problem and will tear into that project if air leak test warrants. The repair kit and a pre-mix fuel pump are not that much different in price so I'll try to fix the VRO pump if I can. Any tips on repairing the fuel pump? Secret tricks? Or if I follow the service manual I should have no suprises? Any and all suggestions and advice is welcome. Thanks again.

 

[johnson89]

Re: '97 90 SPL VRO too much oil

I had this problem a year are so back,,,here is what I did..http://forums.iboats.com/showthread.php?t=451522.....the boat is used every tuesday an run perfect..........

 

[kjdunne]

Re: '97 90 SPL VRO too much oil

Johnson89, did the new pump match up to your existing hoses and manifold, or did you need to replace / reconfigure them. How about mounting the pump? Which part # pump did you use? Disregard my reply to your old thread, I forgot where I was and just started typing.

 

[johnson89]

Re: '97 90 SPL VRO too much oil

http://forums.iboats.com/showthread.php?t=452021......yes I used the same manifold.I tured the fuel pump upside down not sure if I tured the manifold upside down or not,this was a while back,maybe you can tell by the pic's...the fuel pump bolted right to the motor,not sure if your year motor will allow this,I blocked the pulse line hole with a plug and the new fuel pump has a hole on the back side for the pulse......

 

[kjdunne]

Re: '97 90 SPL VRO too much oil

Johnson89, thanks for the link, my motor looks exactly like your pics, the pump will mount right above where the pulse limiter is. I gave the VRO pump rebuild some serious thought and decided to go the pre-mix route for simplicity and reliability. My parts catalogue specs the same pump # as yours. I'll post performance results after replacement. Still need to verify no air leaks in fuel lines before pump swap, but I think 15 years on the original pump is probably near the end of it's service life.

 

[kjdunne]

Re: '97 90 SPL VRO too much oil

Problem solved! Glad I did the air leak test before tearing things apart. Turned out to be a bad O-ring in the fuel connector at the tank. Would not hold any vacuum with hand pump (brake bleeder type) connected to pump inlet fuel line. I replaced the connector, the hand pump pulled fuel up to the VRO pump inlet and held it for at least 5 min. Reconnected fuel line and ran on muffs, excessive smoke cleared out after a few minutes and all seems normal again. Will take it out for on-water run tomorrow, don't expect any trouble. It's the simple things that I tend to overlook expecting the worst.

 

[Chris1956]

Re: '97 90 SPL VRO too much oil

Another OMS pump saved from the scrap pile. Obviously it pays to test the OMS pump, before you blame it for all your issues.