1999 JOHNSON 150 AT WOT

[sipcruz]

I have a 1999 Johnson 150 v6,Ocean Pro.(J150pxees)The problem I am having is that it will not go passed 4200 at wot.Once at 4200,interm. u could hear a pinging noise coming from the engine area.Like pre-detonation or pre ignition.Once i lower the throttle back to below 3800 rpm,the noise is no longer heard(3800rpm too idle).The engine starts,idles and runs fine until u reach 3800 or higher.I just rebuild all 6 carbs and replaced the gaskets between the throttle plate /intake due to one of the gaskets being pitched.I thought that as going to fix the problem,thinking it one of the cylinders was running lean were the gasket was damaged.I also replaced both thermostat due to one of them being bad.Took it out this week end and still same problem.I am thinking now it might be a timing advance problem.Thank u for any advice.

[Walker]

Compression, spark, fuel. Test them in that order. Test each cylinder for spark at the high rpms.

[peteb]

I have a 1999 Johnson 150 v6,Ocean Pro.(J150pxees)The problem I am having is that it will not go passed 4200 at wot.Once at 4200,interm. u could hear a pinging noise coming from the engine area.Like pre-detonation or pre ignition.Once i lower the throttle back to below 3800 rpm,the noise is no longer heard(3800rpm too idle).The engine starts,idles and runs fine until u reach 3800 or higher.I just rebuild all 6 carbs and replaced the gaskets between the throttle plate /intake due to one of the gaskets being pitched.I thought that as going to fix the problem,thinking it one of the cylinders was running lean were the gasket was damaged.I also replaced both thermostat due to one of them being bad.Took it out this week end and still same problem.I am thinking now it might be a timing advance problem.Thank u for any advice.

[peteb]

I have a 2000 150 and I have the exact same problem that started this season. Replaced plugs and checked compression, all checked out ok. I also drained gas tank and put in fresh gas still the same problem. 4000rpm max and pre-detonation. Have you found anything else out to solve it.