what octane to use, Motor cuts out every 2 minutes

[jyenney]

I have a 1999 75 hp merc. My elevation is 3700 ft. I've been using the highest octane I can get at the pump. Is this correct ?

Also, while running at WOT every two minutes or around there My motor cuts out, it sound like a high pitched baww. It does this for 1 to 2 seconds then returns to normal. Any Ideas ?

Thankyou

 

[sschefer]

Re: what octane to use, Motor cuts out every 2 minutes

I have a 1999 75 hp merc. My elevation is 3700 ft. I've been using the highest octane I can get at the pump. Is this correct ?

Also, while running at WOT every two minutes or around there My motor cuts out, it sound like a high pitched baww. It does this for 1 to 2 seconds then returns to normal. Any Ideas ?

Thankyou

90-91 octane is fine. The high pitched baww sounds like a fuel starvation problem. Check the tank vent. If it is starvation, continued operation could severely lean out the engine, scuff piston skirts or melt down piston(s).

 

[jyenney]

Re: what octane to use, Motor cuts out every 2 minutes

Thankyou,

That is what the guy riding with me said it sounded like. I also have problems filling my fuel tank. I'll check out my fuel tank vent.

Thanks a bunch

 

[JB]

Re: what octane to use, Motor cuts out every 2 minutes

87 octane regular is what you need to use.

The notion that "premium" fuel is higher quality than regular is a myth. It is more likely to harm your engine than help.