OMC smoker

Zebramidge · Sep 15, 2001

First boat. Boston Whaler Rage OMC Turbojet 115 inboard/outboard. Use it as flyfisherman taxi on skinny river water from bar to bar. Benchmarking maintenance. New plugs. Tightened up a couple leaky fuel fittings. Changed out leaky VRO. Replaced fuel filter, lower unit gear oil. Did comp test: 145/130 on starboard pistons and 125/125 on port pistons. Checked spark, replaced one faulty connector. Good spark now to all pistons. Decarbed with Merc tuner product. It runs well, but smokes like Keith Richards in a *****house at startups and when I put flush unit on it at home. I'm not the most popular guy at the ramp or in my neighborhood for that matter. Seems like a lot of guys here know what they're talking about. Anyone have an idea of what might be going on with the smoking?

JB · Sep 15, 2001

Re: OMC smoker

In suspect that the VRO is living up to its reputation by pushing too much oil into the engine, Zebramidge. I don't really know how to check this on a jet application. If it were an outboard I would disable the VRO and put 50:1 premix in it, if only to test my hypothesis. Ferrying flyfishermen from bar to bar, huh? Sounds like a really tough job.

Good luck. Red sky at night. . . JB

Zebramidge · Sep 15, 2001

Re: OMC smoker

Good hypothesis. At least we thought so when we replaced the first vro seeing fuel leaking from it. Same symptoms with new vro. Another wrinkle I forgot: the boat was originally sold and used at 5000 ft. plus in Flagstaff, AZ and Albuquerque, NM long before the guy I bought it from had it. Could be they re-jetted the carbs for higher altitude and never changed back for lower elevat ions like Phoenix and the Colorado River. Would that contribute to bad oil/fuel mix and smoking? As for ferrying, I'm usually one of the flyfishers and the bars are made of gravel...

clanton · Sep 16, 2001

Re: OMC smoker

The only way you will know about the carb jet size is take one out and look at size stamped on jet. Carb jet size will not effect fuel and oil mix going thru VRO2 pump. Check fuel lines,anti-siphon valve, all fittings,and fuel tank pickup tube for pressure leaks, vacumm leaks, correct size, and restrictions. If fuel system from tank to pump is to specs new pump has bad check valve. Was oil tank cleaned and filter changed when new pump installed? Did you do compression after the decarb?

Zebramidge · Sep 16, 2001

Re: OMC smoker

Thanks for the input Clanton. All fuel lines look dry and clean before the pump. Not sure where the antisiphon valve is or how to inspect pickup tube. I did check compression after the decarb and saw drop to 140 on high piston, all others the same. Suppose I could decarb again. Oil tank was not cleaned before/after install of new pump. Did replace the fuel filter. Is there an oil filter as well? Could it be that vro is working fine and there are other reasons for smoking?

clanton · Sep 16, 2001

Re: OMC smoker

The anti-siphon valve is on the pickup tube,on fuel tank, where fuel line connects to tank, 3 things cause excessive smoke at startup and running, fuel line restriction, fuel line sucking air, check valves in oil side of pump. Oil filter inside of oil tank, tank should have been cleaned and filter changed when new pump installed. I think that it will always smoke some, because the oil and gas is mixed. Change brand of oil.

Zebramidge · Sep 16, 2001

Re: OMC smoker

Thanks C. Will do easy stuff first. Pull fuel pick up and clean filter screen and change brand of oil. If that doesn't do it, I'll pick up a vacuum gauge and test fuel system delivery before and after vro for restricted anti-siphon and faulty vro check valves. Holding off on oil tank maintenance because if this vro is bad too I may be pre-mixing!

rmeyer33 · Sep 17, 2001

Re: OMC smoker

Zebramidge: I also have a Boston Whaler Rage 15 115hp OMC. I can get around 4900 rpm max and about 32 mph (attempting to get more). I just purchased OMC Engine Tuner and was told by the boat shop that my engine had a "valve" of some sort to attach the can to. I cannot locate this "valve" -- how did you do your decarb? Thanks for your help.

clanton · Sep 17, 2001

Re: OMC smoker

This engine does not have that valve.

Zebramidge · Sep 17, 2001

Re: OMC smoker

Clanton is right. There isn't any valve. Just fired the stuff right into the carb intakes. Stalled it out and waited 15 minutes. Interestingly, another boat came over to see if I needed help. He thought the engine was on fire. Ran it wide open for 5 minutes as directed. Picked up a couple hundred rpms. Now at 4700 at wot. Not sure of speed but plenty fast for a 15 ft. jet boat when it hits a couple of wakes and starts sucking air below. Careful what you ask for. As for suggested fuel line tests, it looks like I'll need both a vacuum gauge and pressure gauge to test lines coming and going from vro, eh Clanton? Are these expensive devices? I'd take it to mechanic but both I've talked to strongly suggested capping the vro and premixing. Tough to do right after you've coughed up $220 for a new pump...

Rex · Sep 18, 2001

Re: OMC smoker

I AGREE WITH CLANTON. NEED TO CHECK THE HIGH SPEED JET. GOOD LUCK REX

clanton · Sep 18, 2001

Re: OMC smoker

Model number , and I can give you jet size.

Zebramidge · Sep 18, 2001

Re: OMC smoker

Getting a little confused here. Thought recommendation was to eliminate possibility of fuel restriction, air entering fuel system or vro failure. Plan on testing pre-pump with vacuum gauge and clear vinyl hose when I can get it in the wateraccording to OMC service manual test has to be done full throttle for two minutes under load. Still not sure how I'm gonna pull that off with an i/o motor. Any suggestions will be appreciated. If all checks out pre pump for obstructions and air in system, will test post pump with pressure gauge to check vro. Not sure of engine model # but manual covers Turbojet 115 Models 115JEEO, 115JPEO and 115TJEO. Can't find any mention of carb jet options in service manual.

mthrash · Sep 19, 2001

Re: OMC smoker

I have a 1994 Four Winns Jet boat with a 90hp OMC engine which smokes excessively at start-up. About a month ago, I disabled the VRO and started to pre-mix the oil and fuel. This did not have any effect on the problem. As an experiment, I installed a shut-off valve on the outlet of the fuel pump so that I could run the fuel out of the carbs after a day of boating. The effect of this is that there is very little smoking at start-up. I think the problem stems from the fact that when you shut-off your engine, some of the fuel in the float bowl evaporates which leaves a mixture rich in oil. Mark

Zebramidge · Sep 19, 2001

Re: OMC smoker

Thanks Mark. Very resourceful solution that akes sense to me. On my motor, between tank and vro fuel intake there is a primer button that's designed to help fuel side catch up to oil side on startups. (This is in addition to solenoid choke device.) You push it a few times until there is resistance and supposedly carbs are good to go with fuel. Seems to get things going quicker but there is still significant smoking. Like J.B. and Clanton I am still suspicious of vro mixing ratio.

Zebramidge · Sep 20, 2001

Re: OMC smoker

Ran in-water full throttle vacuum test this am. Vacuum was good, -3 on gauge prepump, which is well within OMC specs according to manual. Did notice some air bubbles though in vinyl hose piece I inserted after inline primer button device but before fuel filter. Reconnected fuel line and this time put gauge and vinyl hose between tank and primer button device. Significantly fewer bubbles, much greater fuel flow. Appears primer is kaput. Ran out of time. Thinking about bypassing primer, as I don't even use it half the time, and see what happens. Examined pick up tube in tank as Clanton had suggested thinking I'd have to clean up a dirty screen. No screen or filter on line in tank at all. Tank and fuel did look clean however. Check valve looked okay, clean and functional. By the way, motor smoked like a pig at startup and throughout the morning at low rpms.

mthrash · Sep 21, 2001

Re: OMC smoker

Zebramidge: There is definetely something wrong with these engines, but what it is i'm not quite sure. My solution was to disable the VRO pump and install the shut-off valve to run the fuel out of the carbs before shut-down. I am also currently using Amsoil 100:1 synthetic lubricant, which is supposed to reduce smoke. I don't have as much of a problem at start-up anymore, but I do seem to have some smoking at low speed idle. I really don't think there is much of a difference in using the Amsoil, which is mixed at a ratio of 100:1 as opposed to that of regular outboard oils which are mixed at a ratio of 50:1. Although your fuel/oil ratio is less with the Amsoil by volume, I think it may be the same on a mass basis because the Amsoil weighs significantly more than your conventional two-stroke oil. Let me know if you have any success. Mark

Claus · Sep 23, 2001

Re: OMC smoker

Hi I´m from spain and happy to found this web-site. I own a used Novurania Equator 360 w/ OMC TurboJet 115 (S/N: G04144596) and having the some problems, also the engine starts very bad (need a lot of times to run). This is the reason for searching for some help, because her in spain I could´nt found any help, this type of motor is here very rare. For serviceing the OMC-engine I´m looking for any manuals (Service Manual / Technical Maintenance Manual / etc.)!! Could someone help me?

Thanks for any information. Best regards from the "Costa del Sol"

OMC smoker

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