New Mecury 40 hp starving for fuel .......maybe?

[ThePinkPanther]

My son is the proud owner of a new Stacer with a new mercury 40 HP "triple carbi" outboard on the back.

First day our during the run-in on 25:1 the plugs fouled up and were replaced by Nitro Marine on the Gold Coast.

Next trip out, same again ......................

Next trip on 50:1 the motor now runs as new for about sixty minutes and then gives all the symptoms of fuel starvation such as the fuel tank air vent being turned off.

When it is shut down for a minute or so, it roars into life and then goes through the power loss routine again, over and over again. Once it reaches this stage, it never recovers and he has to limp home on minimal power.

To me it sounds like a fuel starvation problem but even with the fuel tank cap completely removed the motor still won't play ball!

He assures me the fuel line is not kinked, is "in" properly and the oil/fuel mix is correct.

Just wondering if this latest Merc could have some sort of known problem in the fuel supply area?

[charlie09]

Bull...!!! Mate I sit and read this post in pure amazement. I have a 40 hp Merc XR Lightning with exactly the same problem. I'm in the process of putting a video of how my motor was running if someone might be able to diagnose it.

Cheers
Vince

[charlie09]

Ok it would seem that I cant upload the video :(. So the symptoms are the same as what ThePinkPanther mentioned. I also done the same things as remove the fuel cap of the tank and made sure that the line wasnt kinked or loose connections. Still no joy. I used to get 25 or 26 knts at WOT but now barley managed 18.

Fresh fuel, oil injected, new motor only 40 hrs or so. Had its first service at 20 hrs and nothing wrong with the motor. Motor sounds like one of those old victa mowers from the '70's

So what gives? Any ideas? Any commenst appreciated.

Cheers
Vince

[Bay_Ray]

I have had the same issue, but with an old 60 hp mariner. I thought it may have been air leaking into one of the fuel fittings either at the tank or engine, but ended up selling as is before I figured out what it was. Maybe check your o rings on the connections? Bieng a relatively new engine it should not have these issues, Maybe try and run a hotter spark plug? Is it possible that the plugs are fouling up?

[ThePinkPanther]

Thanks for yhour reply Vince - worth a post wasn't it, in the faint hope somebody else had the same problem!

Sounds like you haven't had any luck with it so far?

What have you tried so far and other than the video, what options do you have left?

Cheers

PP

[charlie09]

I took out the plugs and had a look at them. Plugs 1 and 3 were ok but No 2 was a little "darker" than the other two. By darker I mean almost sooty looking. I'm not a mechanic but I would think it might be the "Capacitor Charging Modual or CDM". I assume that this is what generates the spark for the plugs. Does this sound right?

Vince

[Bay_Ray]

As far as I know the plugs should all be burning evenly, I would give the local mercury dealer a buzz and see if they can steer you in the right direction, Sounds a little odd that one plug is oily? Maybe replace it and see how she runs?

[Bay_Ray]

How did you guys go? My father in law has a new 60 hp mercury 3 cyl engine and it has been recalled to have the fuel bulb and line re-fitted. Similar symptoms to what you guys were experiencing with your engines.

[ThePinkPanther]

OK, all fixed but what a disgrace that Mercury knowingly produce outboards with confirmed defects. Rather than recall the product, they just provide a fix to the dealer who then does the tweaking and the motor then runs as it should.

Apparently about one of twenty come out with these defects - don't ask me how.

So, fix was:

1. New "hot plugs"

2. Oversize carbi jets

3. New spark plug leads

All this was done and the motor that had failed four times out of four from brand new, ran like a charm, never missed a beat in four hours of running.

Hope this helps others with the same problem.

[tunaticer]

At least you ended up with a good result, pretty crap that merc took so long to rectify the problem though.
Until you made your final post I was going to suggest checking the pressure supply from the fuel pump to see if it is a gasket or pump problem.

Did they fit surface gap plugs or standard electrode types?

For two strokes I will only run the surface gap plugs, they never oil up or wear out. My current plugs are just shy of 16 yrs old now and still like new where it counts, the outside has now got surface rust showing after all that time. They sure make a difference if you do periods of trolling or slow going.