1995 70HP Johnson Surging/Stumbling

[bdsandman]

Here's the story... 1995 70HP Johnson that sat for almost 5 years. Emptied the gas tank, added new fuel lines, rebuilt the carbs, new water pump, new plugs, changed the inline fuel filter. Compression checks out at 128-126-127.

After some intial problem which have been solved, the motor idles and runs great throughout the exceleration range. However soon after getting over 5000 RPMs it will run great for a few seconds and then begin to surge and stumble. The higher I go in the RPM range the worse it gets. Eventually if I throttle up and back off it will settle in and run almost perfectly up to about 5000-5200 RPM's. After that if I throttle up again after a few seconds it will start to surge and stumple again. It seems like it wants to go but just wont break thru. It will jump up to 6000 RPMs for a few seconds and then drop back to 4500-5000 and back and forth.

The ball stays hard. I'm on my second new tank of gas. I tried it on a portable tank to eliminate tank vent or pick up tube problems and it did the same thing. I'm contemplating the fuel/VRO pump but don't want to go down that road until I'm sure because they're not cheap. Besides it almost seems to inconsistent a problem to be that. One note, it almost seems to be worse when I'm cornering or bouncing but I'm not really positive about that.

Any suggestion??

[tashasdaddy]

did you replace fuel bulb. it should be plyable, and not stay hard, once the fuel pump starts pumping. did you remove all the jets and clean them. not just shoot cleaner thru them.

[bdsandman]

Brand new... It is pliable. I just meant that it's not going soft. I also ran it on a portable tank with it's own fuel line and primer bulb and it made no difference.

Forgot to mention. I did instal a fuel/water separator also and replaced the filter cannister after burning through the first tank of gas to be sure I had all the water out of the system.

[bdsandman]

Any Suggestions??

[Daviet]

Maybe an ign problem. Do you see any crackes in the coils? Sometimes you can run an engine on muffs, use a mister bottle and spray the coils and wires and check for spark shorting to ground. Check the plug boots for shorting to ground. Just thinking?

[bdsandman]

Appreciate it... I was thinking maybe coil. Definitely worth a shot.