Logo
FULL SITE MENU

Oily gas forming on water at idle

F

frankfish@1

New member
I have a 1999 150 hp Mercury Optimax. While winterizing in a tub, I noticed oily gasoline forming on top of the water. I can't identify where it is coming from. It's also taking three to four turns of the engine before the engine will maintain an idle.

When it does idle, it idles rough and the engine sometimes stalls. When I put it in gear it coughs and the prop slows with each cough. Once I increase rpms the engine seems fine. Gasoline is non-ethanol and treated with an additive. Very little to no smoke out of exhaust.

I changed spark plugs and wires and installed a new fuel line / primer bulb but this didn't help. Any ideas what might be happening? Please keep terminology simple (or at least explain what a part's function is if mentioned), as I'm not all to familiar with various parts. Thanks.
 
bilge rat jim said:
What was your winterizing procedure? And- what colour are the injectors- black or blue?
Click to expand...

I should have mentioned that the idling and starting issues were noticed months before winterizing the boat. It wasn't until I ran the engine in a tub of water did I notice how much oily gas was accumulating. I'm thinking its coming out the exhaust within the prop area? Can you direct me where the injectors are and I will see if they are black or blue. Remember, I'm a novice when it comes to engines. Thanks.
 
frankfish@1 said:
I should have mentioned that the idling and starting issues were noticed months before winterizing the boat. It wasn't until I ran the engine in a tub of water did I notice how much oily gas was accumulating. I'm thinking its coming out the exhaust within the prop area? Can you direct me where the injectors are and I will see if they are black or blue. Remember, I'm a novice when it comes to engines. Thanks.
Click to expand...

I took a pic. I'm assuming these are the injectors. I would have to say they are blue (look more like purple to me), but I think this is what you are referring to.
Boat engine.jpg
 
probably...unless you have two problems..rule number one with me is to always fix what i see broke first....
always start troubleshooting any outboard with a compression and fire check..
 
Your motor has had the injector update earlier ones was black. You either have a cylinder not firing(compession/ignition module/bad plug) or a injector flooding. If you have never had them cleaned it is time...Brucato can clean and flow balance them for you
 
faztbullet said:
Your motor has had the injector update earlier ones was black. You either have a cylinder not firing(compession/ignition module/bad plug) or a injector flooding. If you have never had them cleaned it is time...Brucato can clean and flow balance them for you
Click to expand...
Yep, that's where i was going with injector colour question. I'd start by testing for continuous spark on all cylinders at start-up and idle (use an inductive timing light, not a spark tester), and a compression test. If compression and spark are OK, you have a fueling problem, and the only practical way to diagnose this is with an engine scan.
 
Back
Top