LOW RPM'S Mercruiser 454 EFI

[klaffey]

My '99 Sea Ray 400 Sundancer Tops out at 2700 RPM. What should the WOT be and any ideas on what could be the issue. I have replaced both fuel filters. I also ran a gallon of Sea Foam through it and it improved temporarily to about 3000 RPM. Any help is appreciated.

 

[Philster]

Re: LOW RPM'S Mercruiser 454 EFI

I suggest you add a whole lotta background.

Did you wake up one day happy with your 4700 RPM WOT run from the day before when she hit 55 mph only to find out 24 hrs later she falls on her face at 2700?

Sounds like a fuel issue... but hard to say.

Give us all the info and history you can. 350 carbed V8? Merc? Volvo? 454?

 

[Bondo]

Re: LOW RPM'S Mercruiser 454 EFI

Ayuh,... Is it moored/ docked,..?? how much Marine Life on the hull,..??

 

[klaffey]

Re: LOW RPM'S Mercruiser 454 EFI

Really has been "flat" since purchase a year ago. Ran a couple of gallons of Sea Foam through and improved temporarily. Bottom is clean. Was sanded and painted when I purchased the boat a year ago and it is in a Freshwater Midwest Lake.

Have checked and changed fuel water separators. Compression is consistent and good across all cylinders.

I suspected water in the fuel, but have not picked any up in the separators.

It is a fuel injected 8.1 Horizon.

Starboard side engine is worse as it will only hit 2500 RPM WOT.

Engine starts fine and has never ran rough, just no RPM's.

 

[fishinpa]

Re: LOW RPM'S Mercruiser 454 EFI

So it is 2 engines both running poorly ??

and have since you bought it ??



fish

 

[klaffey]

Re: LOW RPM'S Mercruiser 454 EFI

One about 1000 RPM lower than the other and yes since purchase. Boat had been sitting for 2-3 years prior to purchase.