1998 Mercury 3.0 225 EFI

[2boys]

I have a 1998 Mercury 3.0 225 EFI that recently will on turn 5100 RPM. It use to turn 5800 - 5900 RPM without any problem. I have changed the plugs, fuel line, fuel filter. It does not appear to miss at low or high RPM's. I have ran injector cleaner in the last 3 or 4 tanks, but no change.
Any suggestions?

[western angler]

Check to see if the butterflys are fully open, check the throttle position sensor voltage. That's a start and I am sure Don will have some more ideas.

[Props4u2]

Check compression io make sure all are healthy.
Also check fire to all six cylinders with a timming light.

[EuropeanAM]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Props4u2 &raquo;</td></tr><tr><td class="quote">Check compression io make sure all are healthy.
Also check fire to all six cylinders with a timming light.


</td></tr></table>

+1

Would also be a good idea to verify your FUEL PRESSURE.

Report back with your results..... and we'll go from there.

[buckchsr]

I am going to jump in, I have the exact engine with the exact problem. Compression is perfect, fuel pressure is good, and I have fire on all six. So far I have replaced the plugs, coil packs, fuel filter. What do you think it is? Injector, ECM, Reed, Stator??? The engine starts and runs great, just not getting the rpm's it should and kind of drops back a bit when you give all the thottle if that makes sense. Thanks for any help


Modified by buckchsr at 10:48 AM 6/23/2010

[Ranger200c]

I had that same problem, motor wanted to bog at WOT and I could only get about 4800 rpms, ended up being clogged injectors, had them cleaned and flow check and now I'm hitting the 5800 mark and no probs.

[EuropeanAM]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by buckchsr &raquo;</td></tr><tr><td class="quote">I am going to jump in, I have the exact engine with the exact problem. Compression is perfect, fuel pressure is good, and I have fire on all six. So far I have replaced the plugs, coil packs, fuel filter. What do you think it is? Injector, ECM, Reed, Stator??? The engine starts and runs great, just not getting the rpm's it should and kind of drops back a bit when you give all the thottle if that makes sense. Thanks for any help&lt;br /&gt;&lt;br /&gt;
Modified by buckchsr at 10:48 AM 6/23/2010</td></tr></table>

Are you running FACTORY reeds? VERY important question!

[buckchsr]

I am honestly not sure, I haven't replaced the reeds, I assume they are factory.

[EuropeanAM]

As a starting point, you might want to check into this:

http://www.bbcboards.net/zerot...first