Mercury 90 hp 2 stroke - Difficulty with cold start up and sluggish

[JWBC]

Hi Guys,

For the past two weekends I have taken my boat (90 hp 2 stroke 2001) to the lake and it has been very difficult to cold start. I follow my usual procedure - high rev arm halfway, bulb primed and firm and good battery, key turn. On the latest trip today it took about two minutes to finally turn over and I kept it at higher revs on the ramp until it warmed up and I was satisfied she wouldn't stall. Good water coming from the tell tale. Once it was warm it ran like a dream (good revs and responsive). During the day at short stops and starts I had no difficulty starting it (either directly with the key or with a little key choke after a couple of no choke turns). Engine likely still warm?

However, at my last spot where I stayed longer I had the same difficulty in keeping it going. It started okay initially but as I was bringing in the anchor she stopped completely. I finally got it started after running it at higher revs to get it warm and returned to the ramp without incident (there was no apparent excessive smoke which would indicate flooding).

I brought it home and immediately went to start it again in the backyard and whilst it started after a couple of goes with the key choke it seemed 'sluggish' in revs initially. Again once it was warm it seemed to idle fine. No excessive smoke evident at start up and good water in the tell tale.

As a bit of background prior to these last two trips I changed (without incident) the fuel filter, thermostat, water impeller, spark plugs and leg oil. (I made sure the parts were a mirror image of those replaced) yet I am now getting this problem at start up?.

I am wondering if it might be starved of fuel or the fuel mix has something to do with it (?) (I didn't touch that aspect).

Any ideas would be greatly appreciated.

Jim

 

[Silvertip]

Re: Mercury 90 hp 2 stroke - Difficulty with cold start up and sluggish

Fuel mix would have to be way wrong to cause a starting problem That's not the problem. Water in the fuel may be. Starting procedure, although you may say you've changed nothing in that regard, sounds possible. Two stroke, carbed outboards are typically cold blooded and need lots of choke and a little throttle (via the fast idle lever) when cold. If the parts you changed were responsible, the engine likely wouldn't run well or start well when warm either.

 

[Texasmark]

Re: Mercury 90 hp 2 stroke - Difficulty with cold start up and sluggish

I have the same engine and have the same problem. The little sucker is just cold natured. Have the same problem if I stop for an extended period, just as you do. After chasing a ghost, I just decided to live with it and not worry about it.

HTH,

Mark

 

[JWBC]

Re: Mercury 90 hp 2 stroke - Difficulty with cold start up and sluggish

Thanks guys,

I am starting to suspect the fuel myself. I realised I have had the fuel for about 2 1/2 months stored but with some mercury stabilser in it. I thought this might take care of any water?? Anyway I will throw out the fuel and start fresh.

Also will 'pumping' the high idle lever do anything (i.e additional air) or is it still just as effective halfway?

Thanks Jim

 

[Silvertip]

Re: Mercury 90 hp 2 stroke - Difficulty with cold start up and sluggish

Pumping the high idle lever does nothing but wave the carburetor butterflies at you. There is no accelerator pump on this engine. Use the push to choke feature on the key. In fact, squeeze the primer bulb until firm. Raise the fast idle lever. Turn the key to RUN (not START), now push in and hold the key for a count of 8 - 10. Now turn to START. If the engine doesn't pop off push the key in and hold it while cranking. You shouldn't need to hit the choke with a warm engine, but I always raise the fast idle lever on my 75 HP (nearly identical to the 90) on warm starts as well as cold. I shouldn't, but I get frustrated when I see people people simply crank, crank and crank some more trying to start an engine. 60 day old fuel is also not the issue if the engine runs fine otherwise -- especially if it was treated.

 

[JWBC]

Re: Mercury 90 hp 2 stroke - Difficulty with cold start up and sluggish

Thanks Silvertip,

Your advice is greatly appreciated. If the fuel is not the issue any ideas what it could be or is it likely 'operator error'?

 

[Texasmark]

Re: Mercury 90 hp 2 stroke - Difficulty with cold start up and sluggish

Thanks Silvertip,

Your advice is greatly appreciated. If the fuel is not the issue any ideas what it could be or is it likely 'operator error'?

Silvertip and I are owners of similar/identical engines and told you what to do. You can choose to follow the free, friendly, advice or be merrily on your way. The choice is yours.

Have a glorious day.

Mark