'99 Johnny cuts off at high speed

[jeffbob]

J150plees Starts fine and idles fine. Goes great out of the hole. While running at around 38 mph/3600-3800rpm it goes great will do it all day with about 1/3 pedal left in the hot foot. When I mash it down to go to WOT the motor just cuts off, and when I lift off the throttle it picks back up and starts running great at the lower speed. I know there are bad parts out there, but it recently had almost all electrical replaced with no difference. I am lost. I did check the low-high timing adjustment check but it made no difference

[jeffbob]

BTW we are going to put the old OMC test wheel on it and do some running tests at the ramp. Wish me luck

[ChampioNman]

Did the float bowls get replaced with all the work done? If they did were the high speed orifices moved to the new float bowls?

[jeffbob]

Yes the carbs were rebuilt about 6-7 years ago and it ran fine until last year. It has been 11-12 years since I replaced the fuel lines and bulb, and i'm starting to think it's a WOT fuel delivery problem. Maybe VRO not keeping up?? Could a bad anti siphon valve cause this?

[jeffbob]

When I hold the choke/key in while running it will attain full speed. I obviously have a fuel delivery problem at high speed. Any thoughts as to what my motors problem is?

[DaleH]

Well, if running any ethanol or E10 fuels ... this is what it will do to the lines eventually, see photos ... delaminates the insides, that can then cause the lines to suck flat and not deliver the fuel desired. But with that said, I believe those OMSs have a vacuum-related fuel restriction alarm ...