backfire out of exhaust at idle

[islandboat]

I have '99 225 johnson that ran great until I had the vro pump replaced under warranty. A slight external oil leak allowed the vro to be replaced by dealer free. Now I notice a slight popping out of exhaust during idle while flushing engine (about once every 3-4 seconds, causes engine to idle down and then pick back up to normal 1000rpm idle). Compression is same as 6 months ago- 105/110psi. Engine seems to miss or flutter at about 2500 rpm during full throtle excelleration, but runs great at cruise 4500rpm and tops out at 5600rpm. 3 hours on new plugs, one looks slightly darker. Drained fuel bowls, clean fuel. starts easy and no exess smoke. What should I look at now, coil/plug wire?

 

[vegard]

Re: backfire out of exhaust at idle

btw-- its not a backfire if its coming out the exhaust . I would geuss its a fuel problem

 

[Dhadley]

Re: backfire out of exhaust at idle

If one plug looks dry and "sooty" there is an air leak on that cylinder. That means that cylinder is running lean and would account for what you are describing.<br /><br />Regardless, it needs to go back to whoever changed the pump. Obviously since it was not happening before it has to do with the new pump or the installation. I would not run it anymore until its corrected.<br /><br />Good luck!