I actually don't think this has anything to do with the actual engine;
my guess is carb or timing. Reason being is that the engine is a
brand new crate engine put into my 83 Amer skier. Just about
everything is brand new - the carb is about 6 mos older than the
engine, but still relatively new... here's the issue:

When the engine is cold, it runs great - full power, no hesitation.
Even after running it for 20-30 mins, it is still good. Once I stop
and idle for a few minutes and then try to get back up to power, I've
only got about 1/4 throttle. After that, it starts back-firing and
"starving". If I keep running, it eventually gets to the point where
I can't even idle up without it starving and dies. I try to start it
and it acts like it is not getting any gas at all. I remove the air
cleaner/spark arrestor and confirm that gas is coming from the jets
when the throttle is pushed. I let it sit for a few mins and then it
will start again. But, still no power. I let it sit for 10 or 15
mins and then it starts up, has 90% power (still a slight hesitation
at full throttle). Again, after a while of running and idle, it does
the same thing.

I'm rebuilding the carb today to ensure there is no left over junk -
I've already put a new fuel filter on and new water separator on.
Plugs, wires, distributor - all new. Someone has suggested timing,
but why wouldn't it act bad consistently? Anyway, I'm going to check
that today as well.

Anybody else have any suggestions as to what else to look at?

My guess is vapor lock. Get a fiber spacer to put uunder the carb.

wrote in message
ups.com...
I actually don't think this has anything to do with the actual engine;
my guess is carb or timing. Reason being is that the engine is a
brand new crate engine put into my 83 Amer skier. Just about
everything is brand new - the carb is about 6 mos older than the
engine, but still relatively new... here's the issue:

When the engine is cold, it runs great - full power, no hesitation.
Even after running it for 20-30 mins, it is still good. Once I stop
and idle for a few minutes and then try to get back up to power, I've
only got about 1/4 throttle. After that, it starts back-firing and
"starving". If I keep running, it eventually gets to the point where
I can't even idle up without it starving and dies. I try to start it
and it acts like it is not getting any gas at all. I remove the air
cleaner/spark arrestor and confirm that gas is coming from the jets
when the throttle is pushed. I let it sit for a few mins and then it
will start again. But, still no power. I let it sit for 10 or 15
mins and then it starts up, has 90% power (still a slight hesitation
at full throttle). Again, after a while of running and idle, it does
the same thing.

I'm rebuilding the carb today to ensure there is no left over junk -
I've already put a new fuel filter on and new water separator on.
Plugs, wires, distributor - all new. Someone has suggested timing,
but why wouldn't it act bad consistently? Anyway, I'm going to check
that today as well.

Anybody else have any suggestions as to what else to look at?

On 8 Apr 2007 09:57:42 -0700, wrote:

Anybody else have any suggestions as to what else to look at?

Vapor lock. I believe you can fix it by using a spacer block under
the carb, but I'm not sure.

On Apr 8, 12:57 pm, wrote:
I actually don't think this has anything to do with the actual engine;
my guess is carb or timing. Reason being is that the engine is a
brand new crate engine put into my 83 Amer skier. Just about
everything is brand new - the carb is about 6 mos older than the
engine, but still relatively new... here's the issue:

When the engine is cold, it runs great - full power, no hesitation.
Even after running it for 20-30 mins, it is still good. Once I stop
and idle for a few minutes and then try to get back up to power, I've
only got about 1/4 throttle. After that, it starts back-firing and
"starving". If I keep running, it eventually gets to the point where
I can't even idle up without it starving and dies. I try to start it
and it acts like it is not getting any gas at all. I remove the air
cleaner/spark arrestor and confirm that gas is coming from the jets
when the throttle is pushed. I let it sit for a few mins and then it
will start again. But, still no power. I let it sit for 10 or 15
mins and then it starts up, has 90% power (still a slight hesitation
at full throttle). Again, after a while of running and idle, it does
the same thing.

I'm rebuilding the carb today to ensure there is no left over junk -
I've already put a new fuel filter on and new water separator on.
Plugs, wires, distributor - all new. Someone has suggested timing,
but why wouldn't it act bad consistently? Anyway, I'm going to check
that today as well.

Anybody else have any suggestions as to what else to look at?

If you can look down the carb, and you see fuel coming out when you
pump the throttle, it's probably not a fuel problem. I would start
looking at the ignition, check the points and distributor cap, replace
the condensor. Pull the plugs out and take a look at them. Check the
wires, are they laying on the exhaust manifold? Spray wire dryer on
them and try it. Does the ignition system have a ballast resistor, try
replacing it. How's the connections on the wires going to the
distributor?

John

On Apr 9, 12:27 pm, "Capt John" wrote:
On Apr 8, 12:57 pm, wrote:





I actually don't think this has anything to do with the actual engine;
my guess is carb or timing. Reason being is that the engine is a
brand new crate engine put into my 83 Amer skier. Just about
everything is brand new - the carb is about 6 mos older than the
engine, but still relatively new... here's the issue:

When the engine is cold, it runs great - full power, no hesitation.
Even after running it for 20-30 mins, it is still good. Once I stop
and idle for a few minutes and then try to get back up to power, I've
only got about 1/4 throttle. After that, it starts back-firing and
"starving". If I keep running, it eventually gets to the point where
I can't even idle up without it starving and dies. I try to start it
and it acts like it is not getting any gas at all. I remove the air
cleaner/spark arrestor and confirm that gas is coming from the jets
when the throttle is pushed. I let it sit for a few mins and then it
will start again. But, still no power. I let it sit for 10 or 15
mins and then it starts up, has 90% power (still a slight hesitation
at full throttle). Again, after a while of running and idle, it does
the same thing.

I'm rebuilding the carb today to ensure there is no left over junk -
I've already put a new fuel filter on and new water separator on.
Plugs, wires, distributor - all new. Someone has suggested timing,
but why wouldn't it act bad consistently? Anyway, I'm going to check
that today as well.

Anybody else have any suggestions as to what else to look at?

If you can look down the carb, and you see fuel coming out when you
pump the throttle, it's probably not a fuel problem. I would start
looking at the ignition, check the points and distributor cap, replace
the condensor. Pull the plugs out and take a look at them. Check the
wires, are they laying on the exhaust manifold? Spray wire dryer on
them and try it. Does the ignition system have a ballast resistor, try
replacing it. How's the connections on the wires going to the
distributor?

John- Hide quoted text -

- Show quoted text -

I don't agree. Fuel coming out of the accelerator pump doesn't mean
the main jets are delivering fuel. When you press the gas all you are
seeing is the accelerator pump. The main jets need the engine to be
drawing air though the carb in order to supply gas. But I won't argue
it could be ignition as well.

It definitely sounds like it is heat related. Boat engines often get
hotter when dropped to an idle after running a while. The cooling
water supply gets reduced because of the drop in engine rpm's but
there is still lots of heat accumulated in the block that needs to get
removed. It could be detonation as well if the heads are heating up
too much. Backing the advance off would be another good test.

On 9 Apr 2007 12:06:32 -0700, "jamesgangnc"
wrote:

On Apr 9, 12:27 pm, "Capt John" wrote:
On Apr 8, 12:57 pm, wrote:





I actually don't think this has anything to do with the actual engine;
my guess is carb or timing. Reason being is that the engine is a
brand new crate engine put into my 83 Amer skier. Just about
everything is brand new - the carb is about 6 mos older than the
engine, but still relatively new... here's the issue:

When the engine is cold, it runs great - full power, no hesitation.
Even after running it for 20-30 mins, it is still good. Once I stop
and idle for a few minutes and then try to get back up to power, I've
only got about 1/4 throttle. After that, it starts back-firing and
"starving". If I keep running, it eventually gets to the point where
I can't even idle up without it starving and dies. I try to start it
and it acts like it is not getting any gas at all. I remove the air
cleaner/spark arrestor and confirm that gas is coming from the jets
when the throttle is pushed. I let it sit for a few mins and then it
will start again. But, still no power. I let it sit for 10 or 15
mins and then it starts up, has 90% power (still a slight hesitation
at full throttle). Again, after a while of running and idle, it does
the same thing.

I'm rebuilding the carb today to ensure there is no left over junk -
I've already put a new fuel filter on and new water separator on.
Plugs, wires, distributor - all new. Someone has suggested timing,
but why wouldn't it act bad consistently? Anyway, I'm going to check
that today as well.

Anybody else have any suggestions as to what else to look at?

If you can look down the carb, and you see fuel coming out when you
pump the throttle, it's probably not a fuel problem. I would start
looking at the ignition, check the points and distributor cap, replace
the condensor. Pull the plugs out and take a look at them. Check the
wires, are they laying on the exhaust manifold? Spray wire dryer on
them and try it. Does the ignition system have a ballast resistor, try
replacing it. How's the connections on the wires going to the
distributor?

John- Hide quoted text -

- Show quoted text -

I don't agree. Fuel coming out of the accelerator pump doesn't mean
the main jets are delivering fuel. When you press the gas all you are
seeing is the accelerator pump. The main jets need the engine to be
drawing air though the carb in order to supply gas. But I won't argue
it could be ignition as well.

It definitely sounds like it is heat related. Boat engines often get
hotter when dropped to an idle after running a while. The cooling
water supply gets reduced because of the drop in engine rpm's but
there is still lots of heat accumulated in the block that needs to get
removed. It could be detonation as well if the heads are heating up
too much. Backing the advance off would be another good test.

Putting a fuel pressure gage near the carb might be easiest cheapest
way to pin it down. Could be the pump itself heating up. I've seen
that electric pumps are the way to go for the 351 marine application
but my experience is limited to 352 car engines.

--Vic