My motors is a 99 Mercury 200 EFI Ser # 0G897614. The boat & motor is new to me and I never had a boat with an outboard motor on it, so I have a lot to learn. 1st off, it sat for a few years before I got it, I removed all old gas, and filter before trying to start. Once replaced, it started right up and ran good on the muffs, when I put it in the water, it would troll around at idle fine but when I would try to get the boat on plane, it was like the motor had no power (no rev in engine or rpm). It did this for about 10-15 minutes, then out of no where, it jumped up on plane and I was able to get my 20' Champion up to 58 mph om my GPS. It ran fine the rest of the trip. I took it out yesterday, and it did the same thing, but wouldn't get up on plane for about 30 minutes. Sometimes the engines surges, but most of the time, it just seems like a loss of power. Once the engine started running good, it was fine the rest of the day.
I suspect I have a fuel flow issue. The previous owner said a marine shop installed the electric fuel primer pump to solve a wot issue. I would like to simplify everything and go back to a manual primer pump system, and change the electric fuel tank selector with a manual valve. The electric pump is a Carter 4070 which is rated at 4 - 6 psi output & 72 gph free flow. I found a manual for my Mercury that states if a electric pump is used, it should not exceed 4psi max.
I appreciate any suggestion, hints, or advice. I just never seen one run so bad, and out of no where it takes off and runs well oiled machine