1998 Merc 60 DISASTER heavy smoke & rough idle

[EDDYSTONE EEL]

SORRY FOR THE LONG POST WANTED TO GIVE ALL INFO I KNOW

I have a merc 60 elpt 1998

3 cly 3 carb auto mixing 2 stroke.

Saw it run upon collection went well, Its just been transported (layed down) then put on my boat and its now running very bad.

Starts easy on the key (no choke), starts to idle ok. Its quite a heavy smoker (white/blue not thick black) upon start up but it eases off once its been run for a short while.

The problem I am finding is that when I bring the revs up a little it struggles (seems to be struggling due to lack of fuel) when it comes back to idle its "hunting" up and down almost like a misfire trying to find its idle.

If you do bring the revs up it clears and has the power there until you drop back to idle.

So far we have changed the plugs twice, all have good sparks, compressons are all within 3-5psi of eachother at around 115ish. I have removed and cleaned the carbs as good as I can and re-set the idle screws to the handbook 1 & 1/2 + 1/4 screws out. The float levels look all the same too.

We have also tried a differant set of carbs from a similar motor (50hp) and the problem is still there but a little better. We have found it seems to idle better with the auto-syncro (cold starting choke) engaged but I cannot run it with choke on forever I know.

We have messed around with the idle screws and air mixes etc, as well as a little with the timing and throttle screws we had it idle better and better but still struggling to find the fuel to power her through the revs.

Im told it could be coils etc. There was quite a bit of oil (unburnt) around the plugs when I removed them the first few times less as I played around with the idle screws.

Can anybody suggest what we should do next please im a NOVICE who is at my witts end. I cannot understand how it can be so bad when I seen it run from cold for quite a while prior to purchase.

I have been quoted mega bucks for testing. I am frightened to put it in and be told the oil mixing pump or something just as expensive is faulty.

Would it be possible to cure this by playing further with the timing/mixture etc.

Thank you so much in advance you guys are amazing

 

[achris]

Re: 1998 Merc 60 DISASTER heavy smoke & rough idle

Do you have a manual? If not, then go and buy a Merc manual (Not seloc or cylmer). It sounds like an oil pump adjustment. There is a link lever between the oil pump and the carbs. It sets the oil ratio for the different engine speeds. If you are getting full oiling at low speeds, that could be the problem... The manual also details how to check the flow rate of the pump, to determine if it's faulty or not.

Chris...........

 

[EDDYSTONE EEL]

Re: 1998 Merc 60 DISASTER heavy smoke & rough idle

Hi

Thanks for taking the time to read and reply Chris,

I do have the manual yes, I have run it (for a very short while) with that link removed but it still does the same thing. Is there any way to disconnect the oil mix completley and pre-mix it just to prove thee fault.

I was expecting it to be a fuel problem more than anything else does any one know any other possible things to check

thank you

 

[longshanks]

Re: 1998 Merc 60 DISASTER heavy smoke & rough idle

Hi Eddystone

I have a '98 60 with a jet pump on it, and it is doing very similar things as yours is. starts a bit smoky (no problem). idles fairly smoothly. runs fine at 1/3 to full throttle. sounds great. However, when I gun it out of the hole, it is almost as if can hear cylinders #2 and #3 coming online as the engine accelerates. I'd call it a clear stumble/hesitation, etc. I'd like to be able to give it full power to jump up out of the hole more quickly. I've posted on here before, and others suggested timing.

that may be the same as with your motor. A guys called 'Clams' posted a procedure for motors up to 1988, but ours are 10 years older, so I'm not sure if the same procedure applies.

I just checked, search for my thread called '60 triple hesitates'

good luck, and let me know what you find out.

cheers

 

[CharlieB]

Re: 1998 Merc 60 DISASTER heavy smoke & rough idle

Check your service manual for the oil pump linkage.

I have seen these installed 180 degrees out on the oil pump, leaving the pump near WIDE OPEN at idle and turning down the oil as throttle is opened, WRONG!!!!

Look closely at the manual to ensure that you have your linkage installed correctly.

 

[CharlieB]

Re: 1998 Merc 60 DISASTER heavy smoke & rough idle

Also check carbs for flooding.

Just because you have cleaned and adjusted does NOT mean that one has a poor needle/seat.

With the engine OFF, look down the carb throats while holding pressure on the primer bulb. Any fuel leaking into a throat?

 

[longshanks]

Re: 1998 Merc 60 DISASTER heavy smoke & rough idle

ouch!

thanks for those ideas CharlieB. I just winterized my motor, and it's ready for the -30 that we could soon see here in northern Canada. So any real maintenance on this motor isn't going to be happening until spring.

It's a '98, and I've probably put 25 trouble-free hours on it since any service was done to it. It is a dependable, smooth runner, at any speed. However, when throttling up/accelerating, it has a predictable stumble, almost sounds like what Eddystone Eel is describing, but my motor is at least consistently performing, not hunting up and down.

In the meantime I'm going to look at my manual, and look at the motor, as you've suggested. Come spring, I'm thinking it could be helpful to post a good old UTUBE video of this motor accelerating. The problem isn't that much of a handicap, but it would be nice to get the motor to power up more sharply and smoothly. Some have told me this is a characteristic of triples...

cheers