Un-burned Fuel in Exhaust

chuckb

Cadet
Joined
Apr 18, 2002
Messages
26
I have a 1990 Johnson 120 VRO (vro removed) that seems to be running ok but there is a lot of fuel emmiting from the water/exhaust. I'm sure that all 4 cylinders are firing since the engine will change rpms as I remove the plug wires one-at-a-time. Also, even though the engine was not running at the time, I've seen an oil and/or gas slick forming on my driveway when just sitting there with my cooling muffs attached and only the water running.<br /><br />This problem also has seemed to crop-up about the same time my battery charging system stopped working. Could there be a relationship? Maybe the stator set-up that signals the ignition packs and produces alternator current.....<br /><br />Finally, where would I find the bridge recitifer on this engine? I trust the potted modules above the engine block are the ignition pack but I cant seem to find the rectitifers. Please don't tell me they are intergral. <br /><br />PS This engine also smokes terribly when first started but clears up after 15 second.<br /><br />Thanks in advance for any advice or direction as we only have a few more good weeks of boating left here in the Northeast.
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: Un-burned Fuel in Exhaust

Hi, Chuck.<br /><br />What you are seeing is normal. Unburned fuel and smoke come with 2 stroke engines.<br /><br />Which module is the rectifier? You need a manual, Chuck. If you work on your engine without one you have a fool for a mechanic (according to Steelspike).<br /><br />Good luck. :)
 

rickdb1boat

Supreme Mariner
Joined
Jan 23, 2002
Messages
11,195
Re: Un-burned Fuel in Exhaust

My 1990 70 HP Evinrude does the same thing since I went to mixing my own oil. It runs a little rich at low speeds, since the VRO ran at about 100:1 at idle before I removed it(50:1 Now). I too now notice a "Slick" on the water at Idle and very low speed. Nothing to worry about! It's common!
 

chuckb

Cadet
Joined
Apr 18, 2002
Messages
26
Re: Un-burned Fuel in Exhaust

Hi JB,<br /><br />Thanks for your reply. I agree with you. Smoke is good. No smoke, no oil. I have owned several outboards (all Mercs) in my life and yes, they all spewed out fuel. But this one just started doing it Exxon Valdez style. The puddle that formed in my driveway had a black oil slick coating. I'd hate to leave this in the bay.<br /><br />I do need to buy a repair manual but most of them are very lame in the electrical wiring sections. Can you suggest a good one..........<br /><br />Thanks again,<br />Chuck
 

chuckb

Cadet
Joined
Apr 18, 2002
Messages
26
Re: Un-burned Fuel in Exhaust

Hello Everyone,<br /><br />It's me Chuck again. One thing I just remembered: I've started using a different (Pep Boys) brand of 2 cycle oil. Could using a better brand help?<br /><br />But we still havn't fixed my battery charging/rectifier problem yet. OK Ok ok, I buy a manual ASAP,<br /><br />Thank to all again.<br /><br />Chuck
 

grandx

Petty Officer 1st Class
Joined
May 21, 2001
Messages
383
Re: Un-burned Fuel in Exhaust

Chuck, you should use a TCW-3 two stroke oil. I don't know if Pep boys oil is tcw-3 or not, it'll say on the bottle if it is. TCW-3 (2 cycle water cooled) other 2 stroke oil is made for "air cooled" engines running at higher temperatures than outboards.
 

SCO

Lieutenant
Joined
Aug 19, 2001
Messages
1,463
Re: Un-burned Fuel in Exhaust

I'll tell you what happened with my engine. One day, on the muffs, it belched out a thick gray goo all over the garage door and driveway. Glad it didn't happen in the waterway. May have been because of a new fuel tank. The tank has a 1 way vent valve. It will vent but will also pressurize. Could be that as the boat sat, the changes in atmospheric pressure pumped fuel into the carbs and into the crankcase and loosened up gunk that blew out.
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: Un-burned Fuel in Exhaust

Hi, Chuck.<br /><br />Your best bet for a manual is a Johnson factory manual for your specific engine. Failing that, a OMC manual that includes your engine.<br /><br />Good luck. :)
 

rickdb1boat

Supreme Mariner
Joined
Jan 23, 2002
Messages
11,195
Re: Un-burned Fuel in Exhaust

Good place to get Factory Manual. Great on the electonics diagrams!<br /><br /> click here
 

MFG197

Petty Officer 1st Class
Joined
Aug 26, 2002
Messages
236
Re: Un-burned Fuel in Exhaust

My 89 90hp vro evinrude was leaving more of a sheen on the water than normal. found a leaking fuel filter that was also drawing air and leaking the whole system when at rest.
 

chuckb

Cadet
Joined
Apr 18, 2002
Messages
26
Re: Un-burned Fuel in Exhaust

WW,<br /><br />I cannot see nor smell any fuel in the engine cowling or where the fuel line enters the (now canned) VRO mixer.
 

granpafish

Petty Officer 2nd Class
Joined
Mar 13, 2002
Messages
119
Re: Un-burned Fuel in Exhaust

I had the same problem with a 93 Evinrude 50 hp. The amount of gunk was way past what I felt comfortable about leaving in the water. Ugly loads of black oily deposits on the driveway. My fix was easy and cheap. Got the advice right here on this board. Put a new fuel line on. I mean the main hose from the tank to the engine. It worked immediately for me. It is not a bad idea to change it out every couple of years anyhow. I hope that works for you. Granp***
 
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