1998 Mercury 225 EFI Outboard Issues!!!

[IH8Merc]

I have a 1998 Mercury 225EFI Outboard and I have had a laundry list of issues over the years but that's another story. The latest problem is that it acts as if I have fouled a plug or more at idle to 2,000 rpm but then cleans up and runs fine. I have compression and spark, I have drained my tank and added new fuel. Even when I come off plane as soon as it hits 2,000 rpm it runs rough and sounds like there's a knock. Could it be something to do with the ECU? Any help would be appreciated. And for thoughs that will say get rid of it and replace it with whatever brand they like believe me I have thought about it already.

 

[Sandjob]

Re: 1998 Mercury 225 EFI Outboard Issues!!!

I have had similiar issues. Check these 2 things-Stator and reeds. My issues were at about 1200 rpm to 2000 rpm. Ran fine wot. Replaced reeds and ran 200% better at lower rpms. If you run high rpms you may have some damage to reeds. The stator was giving me problems also. I had a few wires that had rubbbed through and subsequently were screwing with the stator-2 mechanics tried to change my ecu but it was stator.

 

[jesse3]

Re: 1998 Mercury 225 EFI Outboard Issues!!!

I have a 1998 Mercury 225EFI Outboard and I have had a laundry list of issues over the years but that's another story. The latest problem is that it acts as if I have fouled a plug or more at idle to 2,000 rpm but then cleans up and runs fine. I have compression and spark, I have drained my tank and added new fuel. Even when I come off plane as soon as it hits 2,000 rpm it runs rough and sounds like there's a knock. Could it be something to do with the ECU? Any help would be appreciated. And for thoughs that will say get rid of it and replace it with whatever brand they like believe me I have thought about it already.

I have had the same problem with my 2001 250 efi. the mechanic's tell me its normal. Doesn't sound or feel right to me.

 

[jesse3]

Re: 1998 Mercury 225 EFI Outboard Issues!!!

I have had similiar issues. Check these 2 things-Stator and reeds. My issues were at about 1200 rpm to 2000 rpm. Ran fine wot. Replaced reeds and ran 200% better at lower rpms. If you run high rpms you may have some damage to reeds. The stator was giving me problems also. I had a few wires that had rubbbed through and subsequently were screwing with the stator-2 mechanics tried to change my ecu but it was stator.

This is exactly what I have been dealing with. Two mechanics said they just do that. I like your suggestion.