2003 mercury 200 hp

[elppid33]

We have a 2003 Mercury outboard engine. We have been chasing some type of problem for quite some time now.

Description of Issue:

In the water:
When the engine is cold it has trouble starting and staying running at idle. Once you run the engine for a bit and want to idle it will idle all day long.

When you go to restart, you always have to pump the ball again, and it is difficult to start and keep running until you get it running again.

With muffs at home:
We can take the cowling off and see the fuel filter. When we squeeze the ball the fuel filter fills up with fuel, as the engine runs you can see less and less fuel in the filter, until it finally stalls.

It really seems to me that the engine isnt getting enough fuel from the fuel pump. But we are unsure as to why?

We have rebuilt the fuel pump, replaced the squeeze ball, replaced the fuel lines from the water separator to the engine, replaced all the fuel lines at the engine and added hose clamps in place of the black tie straps, replaced the fuel filter, replaced the water separator, had the idle confirmed by a mechanic.

Things left i can think of: The piston device located in the engine block that actuates the fuel pump (unsure of the name of the part) or something in the carbs?

Does anyone have any other suggestions? this is a very frustrating issue, i look forward to any help or suggestions

 

[carholme]

Re: 2003 mercury 200 hp

See this test and give it a try:

http://forums.iboats.com/mercury-mariner-outboards/1978-mercury-800-fuel-issues-618474.html

What is your engine s/n?

Gerry

 

[elppid33]

Re: 2003 mercury 200 hp

Serial Number: 0T700984

I will have to look into the solution there, i had never thought of squeezing the ball when the engine was running. But the main problem sounds very similar to what we are seeing.

The fuel pump has 3 hoses attached to it, one for fuel in, one for fuel out and for vacuum to actuate the pump. What/how is the vacuum generated? Is it possible that the issue is there?

 

[carholme]

Re: 2003 mercury 200 hp

Your s/n comes up as:

MERCURY - (200 H.P. (2003 ))
Serial No: 0T700984 Model No: 1200412AY

Parts and Service Bulletin List:

Search Results - Crowley Marine

The vacuum is generated by the pistons moving up and down in the cylinders and should not be a problem unless you have extremely low compression. You can verify this with a compression test, easy to do and takes ten minutes. Odds are, if it is the fuel pump, it will be a diaphragm puncture or a bad check valve.

You can also test by disconnecting the output line, attach a clear line to drain into a can and crank (not start) the engine and watch for a strong pulsing fuel discharge into the can.

Gerry