Gas in my oil
 

Greetings,

I was on the lake yesterday in my '93, 18ft Thompson 4.3L Mercruiser,
with carburetor and electric fuel pump.

The engine literally locked up when coming to a 'slow down' with the
boat. I tried to restart it and it acted like a low battery. The first
thing I thought of is: "ok we're overheated" but the temperature was way
under 150.

The engine had a pretty big jerk from the starter trying so hard. so I
knew it wasn't a low battery or bad starter. Sometimes I would get it
started and all of a sudden a lock up.
I had to be towed back to the boat ramp. This engine did not overheat. I
felt the manifolds and they wasn't barely even warm.

When I got home - I hooked up the ear muffs and it started right up. Ran
normal. It had me scratching my head.

I checked the oil and noticed it was about 2 quarts over the full mark.
It was not milky. So no water getting in the oil. I drained the oil and
it smelled like gas. I'm guessing gas is getting into the oil from the
Carb. So the engine lock up was from the crankcase being totally full of
oil (and gas in this case.)

Now my questions a Do I just need a Carb rebuild kit, or new Carb? Is
there anything else that can cause this? Has anyone ever had this
problem?
Thanks for any comments/opinions.
Sonny

Sonny H wrote:
Greetings,

I was on the lake yesterday in my '93, 18ft Thompson 4.3L Mercruiser,
with carburetor and electric fuel pump.

Ok definitely "electric" fuel pump not mounted low down on the block???


The engine literally locked up when coming to a 'slow down' with the
boat. I tried to restart it and it acted like a low battery. The first
thing I thought of is: "ok we're overheated" but the temperature was way
under 150.

The engine had a pretty big jerk from the starter trying so hard. so I
knew it wasn't a low battery or bad starter. Sometimes I would get it
started and all of a sudden a lock up.
I had to be towed back to the boat ramp. This engine did not overheat. I
felt the manifolds and they wasn't barely even warm.

When I got home - I hooked up the ear muffs and it started right up. Ran
normal. It had me scratching my head.

I checked the oil and noticed it was about 2 quarts over the full mark.
It was not milky. So no water getting in the oil. I drained the oil and
it smelled like gas. I'm guessing gas is getting into the oil from the
Carb. So the engine lock up was from the crankcase being totally full of
oil (and gas in this case.)

Now my questions a Do I just need a Carb rebuild kit, or new Carb?

Probably just a kit or it might even be as easy as just unstick the
float needle?? There's always the chance a lead plug in the carb's
drillings has come adrift & has allowed a leak.

Is
there anything else that can cause this?

With a marine carb any venting or overflow say from a stuck float
needle is directed down the carb throat. i.e. a serious over flow/leak
of fuel should stop the engine (being too rich not seized:-)) but if you
have a lesser leak it's possible raw fuel can get into the cyl (usually
after/during stops), it gets past the rings & is where you found it.

Change the oil & filter, start it & make sure it's running, idling etc
OK if there is excess fuel getting in from any source it will show in
the running. Stop it & make sure there's no excessive raw petrol smell
down the throat. If all is OK then it's probably just the float
needle/seat, renew or;

If you have an electric pump with adjustable pressure??? make sure it's
not turned up lots too high (equally don't just turn it right down,
creates another problem "lean" at power), so at high vibration & flow
the excess pressure is getting past a slightly worn needle & seat; not a
proper fix & a carb kit with new needle & seat can't be dear.

K
Has anyone ever had this
problem?
Thanks for any comments/opinions.
Sonny

WaIIy wrote:
On Sat, 04 Dec 2004 09:42:52 +1100, "K. Smith" wrote:


With a marine carb any venting or overflow say from a stuck float
needle is directed down the carb throat. i.e. a serious over flow/leak
of fuel should stop the engine (being too rich not seized:-)) but if you


The carb on my 5.7 was lunched (bad float or seal) and there a gas
puddle on top of my engine

Thanks Wally, marine carb I assume??? not supposed to happen save some
overflow can get past the accelerator pump link.


K

WaIIy wrote:
On Sat, 04 Dec 2004 10:28:26 +1100, "K. Smith" wrote:


WaIIy wrote:

On Sat, 04 Dec 2004 09:42:52 +1100, "K. Smith" wrote:



With a marine carb any venting or overflow say from a stuck float
needle is directed down the carb throat. i.e. a serious over flow/leak
of fuel should stop the engine (being too rich not seized:-)) but if you


The carb on my 5.7 was lunched (bad float or seal) and there a gas
puddle on top of my engine

Thanks Wally, marine carb I assume??? not supposed to happen save some
overflow can get past the accelerator pump link.


K


Yup, marine carb on a 1989 5.7 Mercruiser. I was surprised to see the
gas puddled in my manifold.

I bet you were!!!:-) Take care.


K

Leaks past the throttle shafts.

"WaIIy" wrote in message
...
On Sat, 04 Dec 2004 10:28:26 +1100, "K. Smith" wrote:

WaIIy wrote:
On Sat, 04 Dec 2004 09:42:52 +1100, "K. Smith" wrote:


With a marine carb any venting or overflow say from a stuck float
needle is directed down the carb throat. i.e. a serious over flow/leak
of fuel should stop the engine (being too rich not seized:-)) but if you


The carb on my 5.7 was lunched (bad float or seal) and there a gas
puddle on top of my engine

Thanks Wally, marine carb I assume??? not supposed to happen save some
overflow can get past the accelerator pump link.


K

Yup, marine carb on a 1989 5.7 Mercruiser. I was surprised to see the
gas puddled in my manifold.

JamesgangNC wrote:
Leaks past the throttle shafts.

Yes!!!!! thanks James, I knew it was supposed to end up in the throat,
but as you say if the throttles are shut, then ....

Thanks.

K


"WaIIy" wrote in message
...

On Sat, 04 Dec 2004 10:28:26 +1100, "K. Smith" wrote:


WaIIy wrote:

On Sat, 04 Dec 2004 09:42:52 +1100, "K. Smith" wrote:



With a marine carb any venting or overflow say from a stuck float
needle is directed down the carb throat. i.e. a serious over flow/leak
of fuel should stop the engine (being too rich not seized:-)) but if you


The carb on my 5.7 was lunched (bad float or seal) and there a gas
puddle on top of my engine

Thanks Wally, marine carb I assume??? not supposed to happen save some
overflow can get past the accelerator pump link.


K

Yup, marine carb on a 1989 5.7 Mercruiser. I was surprised to see the
gas puddled in my manifold.

Does sound like a stuck carb float. An electric fuel pump with a regular
carb is not a common combination for a 4.3 merc. Are you sure about the
electric fuel pump? 93 is old enough to still have a regular carb. I'd
certainly try a rebuild kit and I'd probably only go as far as the float
bowl when I did it. 4 barrel or 2 barrel?

"Sonny H" wrote in message
...
Greetings,

I was on the lake yesterday in my '93, 18ft Thompson 4.3L Mercruiser,
with carburetor and electric fuel pump.

The engine literally locked up when coming to a 'slow down' with the
boat. I tried to restart it and it acted like a low battery. The first
thing I thought of is: "ok we're overheated" but the temperature was way
under 150.

The engine had a pretty big jerk from the starter trying so hard. so I
knew it wasn't a low battery or bad starter. Sometimes I would get it
started and all of a sudden a lock up.
I had to be towed back to the boat ramp. This engine did not overheat. I
felt the manifolds and they wasn't barely even warm.

When I got home - I hooked up the ear muffs and it started right up. Ran
normal. It had me scratching my head.

I checked the oil and noticed it was about 2 quarts over the full mark.
It was not milky. So no water getting in the oil. I drained the oil and
it smelled like gas. I'm guessing gas is getting into the oil from the
Carb. So the engine lock up was from the crankcase being totally full of
oil (and gas in this case.)

Now my questions a Do I just need a Carb rebuild kit, or new Carb? Is
there anything else that can cause this? Has anyone ever had this
problem?
Thanks for any comments/opinions.
Sonny

"WaIIy" wrote in message
...
On Sat, 04 Dec 2004 09:42:52 +1100, "K. Smith" wrote:

With a marine carb any venting or overflow say from a stuck float
needle is directed down the carb throat. i.e. a serious over flow/leak
of fuel should stop the engine (being too rich not seized:-)) but if you

The carb on my 5.7 was lunched (bad float or seal) and there a gas
puddle on top of my engine

Should not happen if a marine carb! The vent tubes are J shaped to dump the
extra fuel from a stuck float into the throttle bore. Probably what
happened on the original post. The electric fuel pump kept pumping way
longer than it should have. Does it have a pump while engine running
circuit? Should have. Also the throttle shafts on a marine carb have flats
and grooves there they ride in the carb housing to keep fuel inside the
carb.
Bill

Check and make sure you still don't have the mechanical fuel pump attached
to the motor. It the electric fuel pump is down stream of the mechanical and
the mechanical pump has a blown diaphragm you could be pumping fuel directly
into the crankcase.

I had the same problem with my boat.
the float is sticking in the carb, which allows the gas flow to increase
drematicaly. YOU DON'T HAVE TO REBUILD THE CARB!!! Just open it up
carefully. clean out the the area where your float is located. try not to
damage the gasket.
Make sure the float will move up and down very easly.
However, if it does not, then you will need to install a carburater kit.

On Sat, 04 Dec 2004 05:14:35 GMT, "SamW" wrote:

It the electric fuel pump is down stream of the mechanical and
the mechanical pump has a blown diaphragm you could be pumping fuel directly
into the crankcase.

====================================

That sounds backwards to me unless we are using different terminology.

I think of downstream as being toward the engine and upstream as being
toward the tank.

The engine literally locked up when coming to a 'slow down' with the
boat. I tried to restart it and it acted like a low battery. The first
thing I thought of is: "ok we're overheated" but the temperature was way
under 150.

The engine had a pretty big jerk from the starter trying so hard. so I
knew it wasn't a low battery or bad starter. Sometimes I would get it
started and all of a sudden a lock up.
I had to be towed back to the boat ramp. This engine did not overheat. I
felt the manifolds and they wasn't barely even warm.

When I got home - I hooked up the ear muffs and it started right up. Ran
normal. It had me scratching my head.

I checked the oil and noticed it was about 2 quarts over the full mark.
It was not milky. So no water getting in the oil. I drained the oil and
it smelled like gas. I'm guessing gas is getting into the oil from the
Carb. So the engine lock up was from the crankcase being totally full of
oil (and gas in this case.)

When you come off plane and the backwash rams the rear of the boat there is
a possibility of water being rammed back into the engine and causing a
condition called hydrolock. I would think that that mostly happens with
thru-hull exhaust. I don't know if that is what you had, or why it went
away by itself on occasion.
The gas in the oil is possible not related to the lockup condition. If
there were gas being pumped into the manifold, I don't think it would allow
the engine to run, if there were enough of it to cause a hydrolock type
situation, and you imply that the engine was runnning when it happened "as
you were coming to a slowdown". Perhaps you could look into the carb before
and immediately after running the engine to see if the electric pump is
pumping extra fuel past the fuel bowl due to a float valve not completely
closing.
Check the side of the block to see if there is an old manual pump still in
the circuit.
I have a '95 4.3L with electric pump and a 4-bbl carb. On mine, the power
to the pump goes through an oil-pressure switch to prevent the pump from
filling the engine with gas when the engine is shut off. If your pump runs
before you start the engine, or continues to run after shutdown, then look
for that switch, and see if it's working(though that shouldn't cause any
problems on a "slowdown").
You might pull the plugs and look for any signs of water ingestion in the
cylinders by checking the condition of the plugs.

K. Smith:

Yes. Electric fuel in or near tank. There is also some other electric
pump in-line with the fuel line that runs at all times when the key is
on.

When I turn the key switch to the on position, you can hear the fuel
pump come on for about 4 seconds.

Thanks

JamesgangNC:

The fuel pump sounds like the one on my Chevy Silverado.
The tank is located in the middle of the boat under the floor. And it's
got a big "wheel" that you can turn and take off to see the top of the
tank, where the wires go into the tank for the sending unit.
It's a 2 barrel Carb (I think!)
It's got the choke on one side with two "holes" and the other side has 2
more. Maybe it's a 4 barrel?! Who knows!

Thanks,
Sonny

SamW:

I checked again just to make sure. The fuel line coming out of the Carb
goes directly to a fuel filter and then to the gas tank. No mechanical
pump on this rig.
Thanks,
Sonny

skinny32:

Thanks, I'll keep a note of that. I'll try that before I buy anything
for it.
And I better make sure I bring a backup motor when I test it out, just
incase !

Sonny

Floyd in Tampa:

The hydrolock sounds possible. But wouldn't the water in the cylinders
leak through the rings and cause a milky color to the oil?

I'm going to pull the plugs and see if and signs of water appear.
Thanks,

Sonny

Sonny H wrote:
K. Smith:

Yes. Electric fuel in or near tank. There is also some other electric
pump in-line with the fuel line that runs at all times when the key is
on.

When I turn the key switch to the on position, you can hear the fuel
pump come on for about 4 seconds.

Thanks


Ok thanks for that.

The electric pump running with "just" the key is unusual?? usually it's
setup so if the engine isn't "turning" the pump isn't running (mostly
they use the ignition pulses to sense) but;

if that's the case then there wasn't a time when the key got left on???
when the motor wasn't running??? It does sound like the fuel got in
while the engine wasn't actually running, the sudden lockup being a
consequence.

If you don't think that's the cause then it really does sound like the
float needle & seat. No big deal really.

Thanks for getting back.

K

"K. Smith" wrote in message
...
Sonny H wrote:
K. Smith:

Yes. Electric fuel in or near tank. There is also some other electric
pump in-line with the fuel line that runs at all times when the key is
on.

When I turn the key switch to the on position, you can hear the fuel
pump come on for about 4 seconds.

Thanks


Ok thanks for that.

The electric pump running with "just" the key is unusual?? usually it's
setup so if the engine isn't "turning" the pump isn't running (mostly
they use the ignition pulses to sense) but;

if that's the case then there wasn't a time when the key got left on???
when the motor wasn't running??? It does sound like the fuel got in
while the engine wasn't actually running, the sudden lockup being a
consequence.

If you don't think that's the cause then it really does sound like the
float needle & seat. No big deal really.

Thanks for getting back.

K

I don't know about the newer boat setups, but the last gas powered I/O with
an electric fuel pump that I had - ran the power to the fuel pump through an
oil pressure switch. The only time the fuel pump would run was if there was
sufficient oil pressure (either engine running, or, if bowl was dry, the
result of cranking over for a bit.

You don't want an electric fuel pump to run without the engine running.

Eisboch

On Sat, 4 Dec 2004 12:11:46 -0500, (Sonny H)
wrote:

The hydrolock sounds possible. But wouldn't the water in the cylinders
leak through the rings and cause a milky color to the oil?

===============================

That is generally true.

"skinny32" wrote in message
lkaboutboats.com...

YOU DON'T HAVE TO REBUILD THE CARB!!! Just open it up
carefully. clean out the the area where your float is located. try not to
damage the gasket.
Make sure the float will move up and down very easly.
However, if it does not, then you will need to install a carburater kit.


The condition commonly referred to as a "stuck float" is rarely caused by
the float actually sticking. It is usually caused by the valve that the
float operates either sticking, getting worn to the point it won't seal, or
having something jam in it, keeping it open.

I have seen cases where the float was damaged and didn't float anymore, but
that is pretty rare.

I would recommend getting a rebuild kit that included a new float valve and
seat and a complete set of gaskets. If you don't feel up to rebuilding it
yourself you might be better off to take the carburetor to a place that
specializes in rebuilding carburetors and let them do it.

Rod

Floats can hang up if they are bent out of shape.

I have an older 4GC rochestor setup. The float alignment in these carbs is
critical and everything looked fine when the top was off. But put it back in
and it would slowly flood. The problem was the float would rise up and
slightly hit the backside of the float bowl preventing the needle valve from
seating fully. I only discovered this after I installed an electric fuel
pump setup. So much fuel drained into the cylinder it locked and would not
even crank over. I have to assume the engine was wasting a lot of expensive
gas.

"Sonny H" wrote in message
...
Greetings,

I was on the lake yesterday in my '93, 18ft Thompson 4.3L Mercruiser,
with carburetor and electric fuel pump.

The engine literally locked up when coming to a 'slow down' with the
boat. I tried to restart it and it acted like a low battery. The first
thing I thought of is: "ok we're overheated" but the temperature was way
under 150.

The engine had a pretty big jerk from the starter trying so hard. so I
knew it wasn't a low battery or bad starter. Sometimes I would get it
started and all of a sudden a lock up.
I had to be towed back to the boat ramp. This engine did not overheat. I
felt the manifolds and they wasn't barely even warm.

When I got home - I hooked up the ear muffs and it started right up. Ran
normal. It had me scratching my head.

I checked the oil and noticed it was about 2 quarts over the full mark.
It was not milky. So no water getting in the oil. I drained the oil and
it smelled like gas. I'm guessing gas is getting into the oil from the
Carb. So the engine lock up was from the crankcase being totally full of
oil (and gas in this case.)

Now my questions a Do I just need a Carb rebuild kit, or new Carb? Is
there anything else that can cause this? Has anyone ever had this
problem?
Thanks for any comments/opinions.
Sonny