merc 90 power probs

[gooner]

hi have merc 90 [serial # 6473622]that will not go over 200rpm when in the water,[out of water she will go to 450rpm no probs] have changed plugs, coils, new stator installed, stripped 3 x carbs, engine starts first time and sounds great until you try to open her up then she sounds like she not firing on all cylinders and try as she might she will not go above 200 rpm under 200 rpm she's great please help it driving me mad

 

[achris]

Re: merc 90 power probs

Check that the ignition timing is advancing when you open the throttle.<br /><br />Chris.........

 

[gooner]

Re: merc 90 power probs

thanks chris for replying have also checked ignition timing [advance and retard] and it makes no difference any other ideas?

 

[Silvertip]

Re: merc 90 power probs

200 rpm and 450 rpm? Don't you mean 2000 rpm and 4500 rpm? A two stroke won't idle at 200 rpm or 450 either for very long. 1) Compression check, 2) spark check 3) link & sync 4) fuel pump check 5) line, pump & fittings check 6) carb rebuild required to name just a few things to consider.

 

[gooner]

Re: merc 90 power probs

yeah mean 2000 and 4500 rpm [sorry about that]thanks for reply will check as you have said cheers

 

[Clams Canino]

Re: merc 90 power probs

I'm assuming you've run it on this boat before with normal results??<br /><br />-W

 

[gooner]

Re: merc 90 power probs

yeah engine was working fine then one day coming in to port she just would not plain and go over 2000rpm works fine under 2000rpm checked plugs and she was not fireing on 2 x plugs so replaced stator and new plugs now she is fireing on all 6 x plugs and have good sparks on all plugs , stripped the 3 x carbs checked all leads, fuel pump, the plugs do seem to be very oily [is this normal] out of water she sounds ex and easily gets to 4500rpm but as soon as we put her in the water she just will not go over 2000rpm and sounds like she is not fireing on all 6x cylinders any ideas? the suns out and the med looks ex so frustrating <br />[steve, javea, spain]