Save vacation! Sputtering at high RPM/Load

[superbenk]

We have one day left of our vacation on the lake and our boat has developed a problem with sputtering/bogging down at hogh RPM under load. I've replaced the plugs, cleaned the fire arrester, sprayed lots of carb cleaner in the carb & added carb/injector cleaner to a new tank of fresh gas. Sputtering & bogging down seems to be moderately better, but it's still worrisome. I'm afraid there might be gunk in the fuel line or pickup, but I'm not sure as the fuel filter at the pump & at the carb were perfectly clean.

Anything else I can try without getting into the tank or the carb so we can enjoy at least one day on the lake? It seems to be okay under 3k RPM.

 

[gadget73]

Re: Save vacation! Sputtering at high RPM/Load

Did you replace the fuel filter, or just inspect it? How about the water seperating filter? usually thats the first thing I change when having these sort of problems.

 

[superbenk]

Re: Save vacation! Sputtering at high RPM/Load

Did you replace the fuel filter, or just inspect it? How about the water seperating filter? usually thats the first thing I change when having these sort of problems.

The fuel filter is new as of last week. I just inspected it today, but didn't attempt to replace it again since it is brand new. I cleaned the screen filter at the carb, but there was hardly anything in it (couple tiny specs).

 

[P 0 P E Y E]

Re: Save vacation! Sputtering at high RPM/Load

Double check to see if all the plug wires are on all the way

Check to see the throttle cable is actually causing the throttle body arm to fully open.

Look at all the linkage, vacuum hoses and fuel hoses for kinks or pinches

Perform an inspection of the engine for anything loose, chafed or leaking.

Hope you can find the problem, try to enjoy the vacation at under 3k if needed.

Good luck

 

[Robj]

Re: Save vacation! Sputtering at high RPM/Load

What type of engine are we talking about??

Have a great day

Rob.

 

[superbenk]

Re: Save vacation! Sputtering at high RPM/Load

What type of engine are we talking about??

Have a great day

Rob.

3 liter GM (1980 OMC 140 attached to an OMC 400 Stringer). It's the boat described in my signature.

 

[TBTOsterman]

Re: Save vacation! Sputtering at high RPM/Load

Try checking your alternator and battery connections. Three weeks ago my chev 305 started bogging and missing under load. Turned out the alternator wire was loose enough on the nut (alternator side) that the eye was bouncing around on the post. The battery was not providing enough juice for the ignition.

Good luck.

 

[superbenk]

Re: Save vacation! Sputtering at high RPM/Load

Well, the boat came out of the water today. The carb/injector cleaner I dumped in the ta.nk seems to be helpping, but things still aren't 100%. We took a short cruise today at about 2-3k RPM without a problem and I ran it to the marina at around 4k RPM also without problem. Anything over that and it starts sputtering again (it was sputtering at 3k RPM before).

I guess when we get it home, we'll replace the fuel line, clean the pickup screen and inspect/replace the anti-siphon valve (can they just be cleaned?). If none of that solves it, I guess the carb gets rebuilt next.

Does that sound like a reasonable course of action? Am I missing anything?