forward idle and stalling.. on and off problem

[MiracleDriver]

so have had the boat running very well after replacing the distributor and having the carb completely rebuilt.

we've been chasing a forward idle forever, and it still is not corrected 100% of the time.

sometimes the engine runs perfect in all categories, and other (like just now)it will sputter and stall in forward idle.

had it out for a ski this morning and no problems.

just went out for a cruise and I could tell it wasn't running right. pulled it back to neutral and then into gear and yep... it stalled out.

so I opened the hatch and started it up to tune the idle speed screw. didn't help... I backed it off almost completely and the idle would hang high. then I got it into gear by throwing it into gear and past idle. got up to speed and gave it some good gas. then it stalled out at speed, which it has never really done before, at least not since rebuilding the carb and new dist.

when it stalled I opened the hatch and could hear a hissing sound coming from the alternator side of the motor, from the top of the engine by the carb or valve cover, riser area. couldn't pin point it.

I pulled the vacume hose off the carb and tried to suck and blow. didn't seem to do anything. put it back on and went to the idle speed screw...
so I backed the idle screw right out after starting it up (no problem starting it) until it almost died and turned it in until it wouldn't stall. put it in gear and turned it in 1/4 turn. then tested it by putting it in neutral then forward and repeat.

was perfect.

then gave it nearly wot and it ran flawlessly. took it back to the dock. shut it down. start, neutral, forward, reverse. no problems and no hissing like before.

I'm completely stumped. how does it run flawlessly one minute and horribly the next without really doing anything?

[Rick]

RE: forward idle and stalling.. on and off problem

It sounds like a vacumn leak somewhere on the manifold. You can take a can of starting fluid and at idle carefully spray it lightly at the base of the carb. If the rpm increases, it's leaking. Replace the gasket between the plate and carb and the plate and intake manifold. Try again. Don't use to much ether just a short spray at the base of the carb. Good Luck

[MiracleDriver]

RE: forward idle and stalling.. on and off problem

I am leaning that way as well. we've just had the carb rebuilt, new dist. cooling system has completely been gone over. comp test on all cylinders. and numerous people have looked at it.

today is the first time I noticed the hissing sound coming from the the carb or manifold area. because we've had the carb rebuilt and from where the sound came from I will order some manifold gaskets.

is there anything to know when replacing them? pop off the cover, replace and put the cover back on? anything I should do while i"m in there?

thanks!

[MiracleDriver]

RE: forward idle and stalling.. on and off problem

just went out for a ski and it ran great... no doubt later today on a longer run it will act up again

could it be the valve cover gasket?

[MiracleDriver]

RE: forward idle and stalling.. on and off problem

did the quick start technique.

at first it seemed to rev up very slightly, when spraying towards the bottom of the carb at the intake manifold gasket (bottom one, right?). It was hard to tell because my gauges are wacked, but I could hear a definite increase in rpm from the motor.. but very small increase and it did not last more than a second. I repeated a few times to make sure.

then I tried spraying further up the carb; along both spacer plate gaskets and the rev's dropped drastically to the point of almost stalling.

what gives you think?

[MiracleDriver]

RE: forward idle and stalling.. on and off problem

I have received this info - what do you guys think?:

Replacing the gaskets may not
help at all. If this carb has been rebuilt a few times it is likely that
the throttle plate bushings are worn out. From new there are no
bushings, but when they wear out you can remove the throttle plates and
shaft and drill and install bushings.

You can check to see if there is any play there. Grab both sides of the
primary throttle shaft and move it back and forth to see if it is loose.
Then check the secondary throttle shaft.

Another problem, if you can hear a vaccuum leak, might be either the
secondary vaccuum diaphram leaking or a power valve might be screwed.

[bobchris]

RE: forward idle and stalling.. on and off problem

well you have all ready answered what your problem is and verified it as well when the rpms picked up and then again when it stalled, your carb guy did a half *** job rebuilding the carb and you have more than one vaccum leak oh well never listen keep chasing it you'll never reach your tail but its entertaining watching you run around in circles.

[MiracleDriver]

RE: forward idle and stalling.. on and off problem

I screwed the carb down and no more stalling. If I have another leak it is minimal at best because I don't stall at all anymore.