Mercury 402 40HP Carb problem???

[Magic Joey]

Hi folks. First post here - so hope you guys can help.
I've aquired a Mercury 402 40HP motor. It's pretty old looking but I have no idea what year it is. It has orange coloured coils...if that gives you a clue to the year!!
So it on't start... surprise surprise. I have a spark on both plugs and I have compression. Battery is fine and fuel is getting to the carb. It turns over but won't start at all. I have had the carb off and cleaned it thoroughly too.
Tried with choke open and closed.
When I pump fuel through it's getting to the carb (I know because it's pouring out of the air intake when I keep pumping). It's also coming out of a small hole in the carb just below and to the side of the fuel inlet.
So my first question is.... Is that a drain hole - should it be plugged?

Secondly - with the amount of fuel I pumped through (enough to flood it) I would have expected to see some traces of fuel on the plugs when I removed them again to check - but they were totally dry. It looks like fuel is getting into the carb but not managing to get into the cylinder????

Any help would be much appreciated - thanks.

Joe.

 

[garndawg]

Re: Mercury 402 40HP Carb problem???

May or may not help, but you might check to see if the idle is set too low...

Disconnect the throttle linkage (port side, upper link arm) and move the throttle link counterclockwise until it's against the idle stop screw. Crank.

Rotate throttle link clockwise about 10 degs. Crank.

Repeat until the engine fires up.

Note: If you get through the vertical and it still won't crank, something else is wrong.

If none of this makes sense, you really need to buy the Mercury Service Manual. The Clymer also helps. About $30 investment and will tell you TONS about your motor...

 

[JB]

Re: Mercury 402 40HP Carb problem???

Try "Outboard won't start" in Engine FAQs, Joey.

 

[Magic Joey]

Re: Mercury 402 40HP Carb problem???

Thanks guys! Much appreciated.

 

[crem1]

Re: Mercury 402 40HP Carb problem???

Hi!

Cleaning a carb involves removing it and soaking it in carburator gum remover for a day, then putting it back together with a new float and filter.
Replacing plugs would not hurt either.
I assume you have not done any of the things that I mentioned?

Alex

 

[garndawg]

Re: Mercury 402 40HP Carb problem???

Hi!

Cleaning a carb involves removing it and soaking it in carburator gum remover for a day, then putting it back together with a new float and filter.
Replacing plugs would not hurt either.
I assume you have not done any of the things that I mentioned?

Alex

Yeah, that was my next advice if he couldn't get it fire with the timing advanced a bit...

 

[Magic Joey]

Re: Mercury 402 40HP Carb problem???

Hi folks - thanks again for the advice.
I have brand new plugs and the carb has been thoroughly, thoroughly cleaned.
I definitely have compression (tested) sparks on both plugs but no fuel on the plugs whatsoever after pumping and turning over and over and over (choke on and off)...
Does this motor have reed valves? It just seems odd that fuel doesn't seem to be getting into the cyclinder at all.

 

[garndawg]

Re: Mercury 402 40HP Carb problem???

Need to check your timing. Could be the spark is off enough to not fire the cylinder...

No foolin', do the link'n'sync from the FAQ. Takes care of just about every issue except electrical t'shooting, which you should need if you're getting spark...

 

[JB]

Re: Mercury 402 40HP Carb problem???

Joey. What happened when you squirted fuel into the carb as instructed in "Outboard won't start"? Lots of "just cleaned" and "perfectly cleaned" carbs don't work.

It is almost always an expensive waste of time and money to start replacing, cleaning, or overhauling parts before you know what is wrong.

Troubleshoot, troubleshoot, troubleshoot. That is how you get your engine running soon and at minimum expense and trouble.