Merc '86 BlackMax 150hp starts and idles great. At WOT she dies down to about 1200rpm. I pump the bulb and it has no effect. However, if I hold down the choke, then it revs up. With the choke held in, it has hit as high as 4,500rpm. As soon as the choke is released, the engine dies back down again to almost nothing. I have replaced the fuel tank and fuel line to the engine. The gas is new 89 octane. I took out the filter screen before the fuel pump. I'm wondering if the effect of the choke is an indicator. Could it be the fuel pump if the choke has this effect? Is it likely carbs/jets? Could it be electronic related?
