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Author Topic:   2004 Mercury 60 2-stroke stall at idle

Sal A posted 06-29-2014 07:12 PM ET (US)
My engine seems to stall after it has run a while healthily at nice speed (4-5000 rpm), followed by 15 minutes at low idle through no-wake zones.
Is this common? The confidence stream is healthy, and the engine seems to run nice and smooth in general. Any thing I should trouble check?
And no, Jeff I am not looking to repower :)

tedious posted 06-30-2014 09:26 AM ET (US)
It's certainly not unusual - the symptoms you describe are probably the #1 problem associated with carbed 2-strokes. If there is an idle mixture adjustment, that may help. If you haven't changed the plugs recently, that might too, for a while.
Tim
Sal A posted 07-01-2014 07:06 PM ET (US)
Thanks tedious.
It ran fine today, but we did not do the 15 minute no wakes.
vze2gbs4 posted 07-03-2014 11:37 PM ET (US)
Something fuel related-clogged carbs,colapsing primer bulb,water fuel separator.
Maybe idle rpm screws has to be adjusted (higher )so she doesnt stall at idle (600-1000) RPM.
jimh posted 07-04-2014 10:36 AM ET (US)
You might gain some insight into the nature of the problem by this procedure:
--run the engine normally, at which time you probably have normal operation;
--then run the engine at slow speed, at which time you should experience the onset of the problem (stalling);
--shut off engine; remove a spark plug;
--inspect the spark plug to see if the electrode and insulator are wet or fouled with oily residue.
If you find the plugs are becoming fouled after low speed idle, perhaps there is a fuel-air mixture ratio problem at low speed operation.
Also, try using some fuel additives that are intended to promote removal of carbon deposits. Mercury has a 1-2-3 sequence of fuel additives that they recommend for normal operational use in their engines. See
http://continuouswave.com/ubb/Forum4/HTML/007434.html
and also see
http://www.mercurymarine.com/parts-and-accessories/product-overview/ fuel-care-system/
Also, what type of two-stroke outboard oil are you using? If you are using low-cost oil, consider changing to a premium clean-burning low-ash oil like Evinrude XD50. There must be a similar Mercury-branded premium oil--I just don't know the brand name.
If the engine has not been run on premium oil, and has not been treated with any fuel additive, consider running a high-dose of fuel additive as a strong treatment; run the engine at high load and high RPM until you have run several gallons of the treated fuel though the fuel system. This may help burn off any accumulated deposits. Then begin a new fuel regimen using better oil and running a bit of additive all the time in the fuel.
jimh posted 07-04-2014 10:41 AM ET (US)
Oh--forgot to add:
When you have the spark plugs removed, check the spark electrode gap. It is common for the spark gap to erode and the gap distance to become larger than the recommended gap. This may contribute to poor spark at low speeds, when spark voltage might be lowest. Check the general condition of the plugs. Spark plugs for these older engines tend to be inexpensive, about $4 typically.
I have found that spark plug gap erosion often occurs in only 25-hours of running. Annual replacement of spark plugs is often helpful to keep the ignition system working at optimum. Since the plugs are cheap and usually do not need to be indexed when installed, they're easy to replace.
Sal A posted 07-04-2014 05:54 PM ET (US)
Thanks Jim. I have already started the additives... I will try your suggestions, although I need to acknowledge that I have never changed a spark plug before.
:)
Tom Hemphill posted 07-04-2014 08:20 PM ET (US)
From the symptoms you describe, I think air could be entering your fuel supply line. Check the fittings.

quote:
...I have never changed a spark plug before.

Be very careful not to cross-thread the spark plug when installing it. That happens easily but it's difficult to repair. And don't over tighten it.
rtk posted 07-05-2014 07:32 AM ET (US)
Give Fullers a call. They're local Merc experts. They even do housecalls.
http://www.fullersmarine.com/
Rich

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Author	Topic: 2004 Mercury 60 2-stroke stall at idle
Sal A	posted 06-29-2014 07:12 PM ET (US) My engine seems to stall after it has run a while healthily at nice speed (4-5000 rpm), followed by 15 minutes at low idle through no-wake zones. Is this common? The confidence stream is healthy, and the engine seems to run nice and smooth in general. Any thing I should trouble check? And no, Jeff I am not looking to repower :)
tedious	posted 06-30-2014 09:26 AM ET (US) It's certainly not unusual - the symptoms you describe are probably the #1 problem associated with carbed 2-strokes. If there is an idle mixture adjustment, that may help. If you haven't changed the plugs recently, that might too, for a while. Tim
Sal A	posted 07-01-2014 07:06 PM ET (US) Thanks tedious. It ran fine today, but we did not do the 15 minute no wakes.
vze2gbs4	posted 07-03-2014 11:37 PM ET (US) Something fuel related-clogged carbs,colapsing primer bulb,water fuel separator. Maybe idle rpm screws has to be adjusted (higher )so she doesnt stall at idle (600-1000) RPM.
jimh	posted 07-04-2014 10:36 AM ET (US) You might gain some insight into the nature of the problem by this procedure: --run the engine normally, at which time you probably have normal operation; --then run the engine at slow speed, at which time you should experience the onset of the problem (stalling); --shut off engine; remove a spark plug; --inspect the spark plug to see if the electrode and insulator are wet or fouled with oily residue. If you find the plugs are becoming fouled after low speed idle, perhaps there is a fuel-air mixture ratio problem at low speed operation. Also, try using some fuel additives that are intended to promote removal of carbon deposits. Mercury has a 1-2-3 sequence of fuel additives that they recommend for normal operational use in their engines. See http://continuouswave.com/ubb/Forum4/HTML/007434.html and also see http://www.mercurymarine.com/parts-and-accessories/product-overview/ fuel-care-system/ Also, what type of two-stroke outboard oil are you using? If you are using low-cost oil, consider changing to a premium clean-burning low-ash oil like Evinrude XD50. There must be a similar Mercury-branded premium oil--I just don't know the brand name. If the engine has not been run on premium oil, and has not been treated with any fuel additive, consider running a high-dose of fuel additive as a strong treatment; run the engine at high load and high RPM until you have run several gallons of the treated fuel though the fuel system. This may help burn off any accumulated deposits. Then begin a new fuel regimen using better oil and running a bit of additive all the time in the fuel.
jimh	posted 07-04-2014 10:41 AM ET (US) Oh--forgot to add: When you have the spark plugs removed, check the spark electrode gap. It is common for the spark gap to erode and the gap distance to become larger than the recommended gap. This may contribute to poor spark at low speeds, when spark voltage might be lowest. Check the general condition of the plugs. Spark plugs for these older engines tend to be inexpensive, about $4 typically. I have found that spark plug gap erosion often occurs in only 25-hours of running. Annual replacement of spark plugs is often helpful to keep the ignition system working at optimum. Since the plugs are cheap and usually do not need to be indexed when installed, they're easy to replace.
Sal A	posted 07-04-2014 05:54 PM ET (US) Thanks Jim. I have already started the additives... I will try your suggestions, although I need to acknowledge that I have never changed a spark plug before. :)
Tom Hemphill	posted 07-04-2014 08:20 PM ET (US) From the symptoms you describe, I think air could be entering your fuel supply line. Check the fittings. quote: ...I have never changed a spark plug before. Be very careful not to cross-thread the spark plug when installing it. That happens easily but it's difficult to repair. And don't over tighten it.
rtk	posted 07-05-2014 07:32 AM ET (US) Give Fullers a call. They're local Merc experts. They even do housecalls. http://www.fullersmarine.com/ Rich