Mercury 40hp 4 stroke stalling

[AMG08]

I have a 2003 Mercury 40hp ELPTO motor. Got the boat on the water yesterday and noticed a bit of an issue. Last year when I would first start the motor, it seems like it wouldn?t be firing on all cylinders at first. I?d shut it down, re-start and it was fine the rest of the day. It only did this a few times. Now any time I fire up the motor, unless I just shut it down a few minutes prior, it seems be missing. It shakes really hard and sounds rough. I turn it off, turn it back on and it?s good. The motor also wants to stall out when throttle is applied, even after the motor is warmed up. Ill push the throttle down and it will bog or even stall. And once I get up and running, when I back the throttle down to stop the motor doesn?t turn down smoothly like it used to. It almost tries to stall again even while still going 15 mph.

Any ideas on what is going on or what I can check? Thanks for any help.

 

[racerone]

Does the motor have carburetors ?--------------Do you leave fuel in the carburetors between outings ?

 

[sutor623]

In '03 the ELPTO was the carbed motor and the ELPT EFI was the EFI. Serial number would help though.........
What kind of fuel have you been running (ethanol? use stabilizer)? Has basic maintenance been performed?
Some motors have a fuel water separator on them stock, and if you don't change them yarly the filter gets saturated allowing water to make its way past the filter.

Has this engine been setting for a while?

 

[AMG08]

In '03 the ELPTO was the carbed motor and the ELPT EFI was the EFI. Serial number would help though.........
What kind of fuel have you been running (ethanol? use stabilizer)? Has basic maintenance been performed?
Some motors have a fuel water separator on them stock, and if you don't change them yarly the filter gets saturated allowing water to make its way past the filter.

Has this engine been setting for a while?

Thanks for the responses. I'm pretty sure it is the ELTPO, but I will verify tonight. I normally run non-ethanol 91 octane gas in it, though it is possible regular gas was put in at some point. Motor was last ran before fall. Maybe September time frame. I changed plugs and the inline fuel filter last year about this time, and oils have been changed recently as well. I have not noticed a stock fuel/water separator but that's not to say one isn't there.

My plan tonight was to pump out the gas, put verified non-ethanol in with some seafoam and see if that helps.

 

[sutor623]

Ok. First thing we need to do is figure out if it is in fact and ELPTO or not. Did you happen to notice 4 carburetors on the starboard side of the engine? Or an intake manifold with fuel injectors going to it?

Do you need to push the neutral idle lever forward to get it to start/warm up?

Does your motor look like this under the hood? This is the EFI model (which I do not believe you have.)

https://www.youtube.com/watch?v=vMnzBAsZfjk

 

[Yegboats]

Isn't ELPT O oil injected?

 

[sutor623]

Isn't ELPT O oil injected?

I think you are right! But he said 4 stroke so I am thinking maybe ELPT.

 

[AMG08]

Just got home to look at it. It is actually a 2002. Sticker says 40ELPT 4S and SN is 0T425755. I must have got the ELPTO from my buddys motor I guess.

 

[racerone]

Cleaning the carburetors might be step # 1 here.