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Ask Dominick Your Own Question
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I have a 1995 Mercury Mariner 200hp outboard.The symptom is

Customer Question

I have a 1995 Mercury Mariner 200hp outboard.The symptom is that it starts easily but dies after about 10 seconds. While it is running the oil warning horn sounding continuously despite the oil being delivered to the engine. Here's what I have tried: hooked engine up to auxiliary tank that contained a mixture of oil and fuel; replaced the oil level sensor in the remote tank; changed the oil hoses in the engine; rebuilt the fuel pump and checked its pressure/vacuum- per spec; removed the air baffle and sprayed Seafood down the throats of the carburetor; checked the carburetor linkage and the throttle linkage/throttle cable adjustment; went through the setup procedure per Mercury Factory Service Manual including timing adjustment; checked the compression in all cylinders to make sure that oil was being delivered to the cylinders - all cylinders in spec and very close to each other.
When the engine starts, it will run for 10 seconds either at idle or at 3000 rpm but dies in either case. Also I am getting smoke in exhaust, so I think that means oil is getting to the engine. The water pump impeller and gaskets were replaced last season as part of routine maintenance.
What you suggest I try next?
Dan Pisano
Submitted: 1 year ago.
Category: Boat
Expert:  Jason replied 1 year ago.

Hi Dan, my name is Jason.

All Mercurys are cataloged by serial number, can I start by getting that number so I know exactly which engine you have.

Customer: replied 1 year ago.
Expert:  Jason replied 1 year ago.

Got it. What is the history on this engine, have you ever personally seen it run correctly?

Customer: replied 1 year ago.
I have owned it since new and have performed regular annual maintenance (lower unit oil, lube linkages, spark plugs, etc.) on it. The only problem I have had with it was when it and the boat were in storage for 3 years. Then I had to remove some white powder that had plugged the fitting on the output side of the boat's fuel tank. I changed the fuel filters (on and off engine) and the boat ran ok. Occasionally when i went to WOT the engine would slow down or stall, but would catch right away and continue at high speed.
Customer: replied 1 year ago.
My hearing is marginal so I prefer to type even it takes longer!
Expert:  Jason replied 1 year ago.

How old is the fuel in the tank?

Customer: replied 1 year ago.
The fuel in the auxiliary tank is fresh this year. The main tank fuel is old. However, the engine runs the same whether it is connected to the main tank or the portable 6 gallon tank filled with fresh fuel and oil.
Expert:  Jason replied 1 year ago.

There are 3 things that need to be done in order to try and isolate the problem. A compression test, a spark output test, and running it on a portable fuel tank filled with brand new fuel. Are you able to do those tests?

Customer: replied 1 year ago.
All three have been done already, but I can do them again and let you know how they turn out. How do I reach you after the tests?
Expert:  Jason replied 1 year ago.

You would log into the website and then reply back here just like you have been.

When you say they have been done already, did you do the tests or somebody else?

Customer: replied 1 year ago.
I need to go to the boat. I will make contact when I return later this evening. BTW, it is docked at a neighborhood marina in the South River (brackish) in Maryland
Expert:  Jason replied 1 year ago.

Okay keep me posted