Mercury 500EFI Blue Motor Running Poorly
 

I have a 500 blue motor. Last Season i was having a bogging/backfire issue when trying to power up. i took it in and they said the fuel system was the issue so i had the fuel redone. New fuel pump/lines. I was only able to run it one time before i had to winterize. it ran good. I ran it twice this year. The first time i had no issue. On the second run, the motor ran good for about the first half hour, then i had to go thru a no wake zone for about 15 minutes. when i went to power up, to take off the motor wouldn't power up past 3000 rpm. I receive no engine beeps, the temp is good, the oil level is good. I am starting to wonder if it is electronic/sensor related? Has anyone experienced this. Any idea's to look at? Is there any good motor place to take it to around the Detroit Michigan area.

I have just bought this boat 272 fastech at the end of last season. I have a fountain and one thing i am shocked about this boat is it only has one battery.

Check fuel pressure

May be the injectors they are known to go bad on these motors. Might be able to just get them cleaned

Yup, but no guessing....let's get to diagnosing. :)

MAT sensor

Figured it out. It was the lower fuel pump. Thanks for all the help.

Unfortunately I’m back! My question is how did you know which pump?