Portside engine losing rpm after plane

[Sundancer280]

Hello,

quick question—05’ 28 ft sundancer— I’ll get the boat on plane just fine and about 5 minutes later, the port side engine will drop from 4K rpm (cruising speed) down to 3.5k rpm’s and won’t let me go over that even if I push full throttle, it cuts off at 3.5k. In order to keep the boat on plane I’ll have to bring my right engine to 4.5k, but we obviously don’t want to have unmatched rpms all the time. One time I lost the speed, then idled for 20 mins, then got up on plane right after just fine and then ended up losing the rpm’s again. I changed the fuel filters last week but that did nothing. Any suggestions?

 

[scoflaw]

Check fuel pressure while this is happening.

 

[Espos4]

Do you have 1 or 2 separate tanks on that boat?

A clogged fuel tank vent is an easy thing to check.

Once you start to lose rpm’s have someone remove the fuel filler cap. See if it improves

 

[Sundancer280]

Do you have 1 or 2 separate tanks on that boat?

A clogged fuel tank vent is an easy thing to check.

Once you start to lose rpm’s have someone remove the fuel filler cap. See if it improves

Just one tank. Do you happen to know how to check the fuel tank vent? Or where the fuel filler cap is?

 

[scoflaw]

Cap is on port side and the vent is under the cap