4.3L Stalls/Kills at Higher RPMs
 

Ah... the latest in a string of mechanical problems. (Grrrrr.)

Here's what's happening now:

1. At higher RPMs (above 3500 or so, typical holeshot), the engine smoothly revs up, brings the boat up on plane, then dies. RPM gauge drops almost instantly from 4200 to zero. Sometimes at 3500+ RPMs, it'll caugh, start up again on its own for a second, then die.

2. It restarts easily. On the next attempt, it may or may not do the same thing again.

No problems at idle, no problems at slow speeds, no problems starting or restarting.

Some sort of kill switch with an intermittent problem?

Re: 4.3L Stalls/Kills at Higher RPMs
 

UPDATE:

The problem was definitely worse tonight. As soon as the boat would reach about 3000 rpm and plane out, the engine would kill. It would still start easily and run at no-wake speeds without a problem.

THEN...

[dramatic music]

...after trying it a number of times, all with the same result, we motored at no wake back towards the slip. When shifting into neutral prior to entering a downstream channel, the engine died and wouldn't restart. Slow cranks, clicks, etc. Clearly, there wasn't enough oomph to start the engine.

So that $20 paddle on eBay came in real handy -- had to ROW THE FREAKING THING about 200 yards to the slip. :mad:

Any ideas? Would a bad alternator explain all this? Did I kick a dog in my last life?

Help!

Re: 4.3L Stalls/Kills at Higher RPMs
 

Is It An Efi? I Had Problems With My 5.7l Efi That Sounds Just Like Your Problem. Turns Out It Was Just The Batteries. Replaced Them And I Never Had The Problem Again. The Old Batteries Seem To Take A Charge But Was Not Enough For The Efi To Function Right. About 3500 Rpm The Engine Would Just Die, Start Right Back Up And Run Fine Below 3500 Rpm. Hope This Helps.

Re: 4.3L Stalls/Kills at Higher RPMs
 

Nope, not EFI -- good ol' carburetor.

And that was the problem. Apparently the carb was the original (18+ years old) and was badly corroded. The Merc techs at my local place suggested that its age, water in the fuel, and the ongoing effects of ethanol were all playing a role.

Bottom line: A new (well, rebuilt) carb solved the problem, as does ethanol-free gas or treating fuel with Sta-Bil. (Marine formula.)