340DA 2005 8.1L "popping" at high RPMs

[markrinker]

Sea Trial failed for 2005 340DA due to a 'popping' sound (not pre-detonation 'ping') >4000rpm. All other operation normal.

Generator makes similar sounds under high amp load, with or without mains running.

Fuel, right? Not so quick...50 gallons fresh on each side with additive on top of 1/4 tanks...no improvement. Boat goes to mechanic, new fuel filter all three, slight improvement...maybe...but not solved.

All fuel being removed from boat, replaced with fresh at direction of Buyer / Seller agreement. If that doesn't solve it, we are looking at fuel pickups and fittings next.

Anyone experienced this?

 

[bmac]

When was the last time your plugs and wires were changed?

 

[Woody]

Sea Trial failed for 2005 340DA due to a 'popping' sound (not pre-detonation 'ping') >4000rpm. All other operation normal.

Generator makes similar sounds under high amp load, with or without mains running.

Fuel, right? Not so quick...50 gallons fresh on each side with additive on top of 1/4 tanks...no improvement. Boat goes to mechanic, new fuel filter all three, slight improvement...maybe...but not solved.

All fuel being removed from boat, replaced with fresh at direction of Buyer / Seller agreement. If that doesn't solve it, we are looking at fuel pickups and fittings next.

Anyone experienced this?

Can you reach WOT rpms? Did you check fuel tank vents for restrictions?

 

[Do Over]

plugs.......it's ALWAYS plugs with 8.1's.......seriously :grin:

 

[markrinker]

Can you reach WOT rpms? Did you check fuel tank vents for restrictions?

(Thanks for the responses. I will answer them as I have data to do so...checking on last spark plug / wire replacement and remember, the genny is doing this, too!!!)

The marina that serviced the boat after the first failed Sea Trial was able to hit the rev limiters and also noted that no codes are being set. From first hand experience at the Sea Trial, the engines start and run smoothly, cruises nicely, etc. Only under high load does the genny 'cough', and similarly only above 4000 rpm did the mains (particularly starboard main) 'pop'.

I am not aware of anyone checking the fuel tank vents. I will have this done when the fuel is removed from the boat on Monday. Thanks for this idea.

Again, I am very familiar with pre-detonation 'ping' or 'rattle' as timing is advanced on poor fuel. This is not the case. This is why I am now leaning more towards air or fuel starvation, but perplexed that the generator could be suffering from the same malady, unless they share a faulty pickup, or common fuel line.

 

[Ctsearay]

Plugs and Wires, I had it happen to me also. Good luck and let us know how it goes.