86 Mercury 115 A907543 power issue

[blackdog1970]

A couple weeks ago I was at the lake. Boat started and ran fine for maybe 3 minutes. It got up on plane and was running then started cutting out. It will start and idle but only run a little over idle at half throttle. Full throttle it will almost die out. I had all 3 carbs rebuilt and synced. That didn't fix the issue. I have since ran boat with fuel cap open and had a buddy pump prime ball while moving forward and there was no difference. The tank vent is clean. From what I have read it could be a check valve on top of tank where primerline hooks up. Or possible my fuel pump needs rebuilt. Power packs and stator have been replaced in the last 7 years roughly. So I'm thinking it's a fuel issue. I'm thinking on rebuilding fuel pump next. I see what I think may be a check valve on fuel pump as well. I have old style pump on mine.

 

[jimmbo]

When you say "cutting out", do you mean suddenly dying, a misfire, or a bog?

I doubt the fuel pump as having your buddy actting as an additional one didn't improve things. Garbage in the lines, possibly. I suspect Ignition. Switchboxes, Stators, and Triggers can go bad at any time, so being they were replace 7 yrs ago means little. Does it have a strong spark at each cylinder, able jump 3/8"? Condition of the spark plugs? You may have to check the spark at higher RPMs, an inductive timing light will work for that. Check for lose, corroded, damage wiring in the ignition circuit.