Mercury Marine 115ELPT4S, 2005

by Ryan W
(Ithaca, NY)

Motor starts and runs great at RMP less than 4000. As the throttle is increase motor will run smoothly and then begin to run rough/misfire and lose power for approximately 5-10 second then return to smooth operation for 20-25 second then loose power again. This cycle repeats for as long as I have the guts to keep it at the higher RMP.

I have replaced the tank to filter fuel line and the fuel filter. I will be replacing the low-pressure fuel pump and spark plugs this week. But I suspect the issue is inside the VST. I'm concerned about opening in cleaning the high-pressure pump filter because I cannot find anywhere to purchase a replacement gasket or any of the components. Is there a cross-reference table available to translate old part numbers to modern numbers or some other way to identify the correct pump and parts that I should look at?

Additionally, are there other items that might cause this problem that I should investigate?

Thank You in advance