Higher RPM's = Engine Sputter
 

Guys, I took my 1999 28' Z280 out last Friday night, after I just had my fuel tank replaced (ugh), and it ran fine at low RPM's but once I got it on plane and after about 1 minute the engine started sputtering. The more throttle I gave it seemed to make it worse. Then back to cruising speed (10 knots or so) everything was fine.

Any ideas?

I am replacing the Fuel Filter so hopefully that is the problem. This all started after I had the fuel tank replaced.

Should I put some Fuel Injector Cleaner in the tank also?

Thought about replacing the plugs but what a pain. I literally have to hang upside down to get to them so thought I'd try the fuel filter first

Thank you,

Roger

Re: Higher RPM's = Engine Sputter
 

Fuel filter.

If that doesn't fix it, then start looking deeper, but it sure sounds like the filter was just doing it's job. Change it out with fresh and I bet she perks right up for you.

Re: Higher RPM's = Engine Sputter
 

I was experiencing the same exact same symptom after I had my boat for about three years. Found out my dealer/servicer hadn't changed the back 2 spark plugs on my 7.4L...they're difficult to reach without a good set of sockets/universals. The original plugs were still in there.

Ran fine at lower RPM's but sputtered at higher RPM's. A new set of plugs solved the problem.

Just a suggestion.

Re: Higher RPM's = Engine Sputter
 

Thanks for all your suggestions but that did not work. New fuel filter is on, new plugs, and everything is fine up to 2500 rpms, then the engine bogs down.

I pulled the air filter off and found a lot of carbon deposits around the throttle body intake and butterfly so I cleaned both but still does the same. However, when I removed the air filter completely I was able to hit 3000 rpms before the engine bogged down again.

Someone suggested that I put a bottle of fuel injector cleaner in the tank and spray carb cleaner inside the throttle body while underway in order to clear any possible carbon that may be clogging things deeper inside. Any problem doing this? Does this sound like a fix?

This is a 7.4l MPI (454) - fuel injection with throttle body. No carb. All electronic.

Thanks again,

Roger

Re: Higher RPM's = Engine Sputter
 

Re: Higher RPM's = Engine Sputter
 

WetWilly, nothing has changed. The tank was actually rebuilt, i.e., the bottom was replaced and everything else put back in the way it came out. So, I'm hopeful that these fluids will work. When I pulled the air filter off the throttle body, you wouldn't believe how much carbon buildup there was so if there was a lot on the outside of the butterfly I can only imagine how much is inside playing around with the injectors themselves.

Thanks for the quick response - I sure hope this works or I may be looking at a bad fuel pump, which I'll probably have to remove the engine to replace :-)

Roger

Re: Higher RPM's = Engine Sputter
 

I wonder if a Sea Foam treatment would benefit you? Bottle or two in the fuel tank, as well as fogging the intake? :confused:

Re: Higher RPM's = Engine Sputter
 

What in the world is Sea Foam in a bottle?

Fogging the intake?

I'm getting ready to put a few bottles of Fuel Injector cleaner in the tank. Is Sea Foam the same thing?

Yes, I'm confused as well. A mechanic said that there is a possibility that something in the brain (everything is electronic on this 7.4) is screwy causing the automatic air/fuel mixture to go haywire.

Roger

Re: Higher RPM's = Engine Sputter
 

http://www.seafoamsales.com/

Works wonders for cleaning out the fuel system. Sold at most automotive stores (said in my best end of commercial announcer guy voice).

Re: Higher RPM's = Engine Sputter