Surging 4.l3 at WOT, only on port engine

[Josh28161]

Hey All, I need some advice on where to look next. I have an 04 280 DA. Twin 4.3 MPI. Alpha drives. My port engine is only getting up to about 3000 RPM at wide-open throttle when trying to get on the plane. As I move the throttle forward and back a little, it surges and varies. The starboard engine at full throttle at full throttle is running about 4000 RPM. I was hoping it was distributor cap related so I replaced the cap and rotor but that did not help. Fuel filter has been replaced and no avail either.
once it finally gets up on plane I can cruise both engines around 3500 RPM with no problem and they sound fine. Both engines idle perfect and start right up. Not sure what I should try next. Any advice would be appreciated.

 

[scoflaw]

Recent tune? Check your fuel pressure

 

[blaster]

In this thread you stated you cracked the distributor mounting base.

http://clubsearay.com/index.php?threads/2004-4-4l-mpi-distributor-issue.105608/

If you did indeed crack the distributor cap mounting this could be the issue.

 

[Josh28161]

In this thread you stated you cracked the distributor mounting base.

http://clubsearay.com/index.php?threads/2004-4-4l-mpi-distributor-issue.105608/

If you did indeed crack the distributor cap mounting this could be the issue.

No that was the other motor.

Also failed to mention in first post, While trying to get on plane, I cold slightly pull back on throttle and that would actually increase rpm’s by a few hundred.

 

[ColoSR]

Most people check bad gas, filters, cap & wires, then fuel pump (cool fuel). Personally, I just got my cool fuel 2 unit changed out and it runs like a different boat. There is another active thread on this under “Any Ideas?”

http://www.clubsearay.com/index.php?threads/any-ideas.105009/page-3#post-1242707

 

[Jimmy Buoy]

If backing the throttles off increases the engine rpm's sounds like fuel starvation. Lack of fuel to the system results in a lean condition the more you introduce air into the engine. Backing off the throttle will reduce air to the engine and allow a more appropriate fuel/air ratio for the engine to produce power again.

 

[scoflaw]

Agree with Jimmy

 

[Josh28161]

Problem solved, thought I would share. Spark plugs. As a buddy used to say, “I would have bet my next paycheck” that the plugs were not the issue. But, I figured they have not been changed since I purchased the boat, so I should do it just to rule that out even though I was convinced it was fuel related. Can’t believe plugs caused that type of issue. SO glad it was not fuel related because the access to the cool fuel systems on twin 4.3’s in a 280 is just about impossible. I’m no engineer but I did stay at a Holiday Inn Express and I cannot fathom why they would not have mounted that system in a more accessible location……