"K. Smith" wrote in message
...
Eisboch wrote:
"Wayne.B" wrote in message
...

On Wed, 25 Jan 2006 00:31:55 +0100, "Steve Lusardi"
wrote:


I think you should identify symtoms,
if you want meaningful help.

It's a 1981 Johnson & Towers marine conversion, supposedly rebuilt
within the last 1,000 hours or so by the previous owner.

My port side engine is taking longer to cold start than it used to,
sometimes needing 8 to 12 seconds of cranking. It used to start on
the first or second turn even when stone cold, and the starboard
engine still does. If it has been run within a day or two it still
starts very quickly. There is very little exhaust smoke at startup
even when cold, and what little there is goes away quickly. The
engine is running well and making full power as far as I can
determine.



There's a guy at our marina who had a somewhat similar problem for a
couple of years. Turns out he had a very small air leak in the fuel
supply line for one engine. It would run fine after starting, (I assume
because the leak was overcome by fuel, but that is pure speculation), but
was hard starting.

Ain't boats fun?

Eisboch (grandkid #5 is a girl!)



Hi again, you say it's making full revs??? a fixed pitch prop is an
excellent dynomometer so if it were seriously down on compression I think
you'd see it in the top end max revs performance.

I think before you go too much further you might check the fuel supply
especially as you say it starts easier after a day, but by then it's well
cold so any mechanical defect in the compression etc would still be there.

Seems granddad Eisboch is on the trail here (he's having a good
day???:-)), fuel filters are a good source of air leaks also. It might be
slowly allowing the fuel to go back down the lines & air in.

These engines as with many Cummins, don't have an injector pump in the
commonly known sense, they have a moderately pressurised fuel rail not
unlike the one in your petrol car. Along this rail (they call it a fuel
manifold in the manual) the unit injectors are sited. There is a
restriction in the fuel rail outlet to maintain feed pressure to the unit
injectors, if the fuel rail isn't properly pressurised by the gear pump
supply it won't start ......... easily. The injectors are driven by the
camshaft & rocker arms the same as the valves are & do the final pressure
increase & injection all in the one movement (pump injector combination).

You can imagine if your fuel system, the gear fuel rail pressure pump as
mentioned (which is also the lift pump usually), the fuel rails & the unit
injectors themselves, get any air in there it will need a few turns to
pump it through & clear it. Once started they can live with a tiny
airleak becasue it just goes straight through the system & out the return
line.


K

I think some people put pressure guages before and after the fuel filter.
You would know what the pressure is when starting and if the fuel filter is
getting clogged.

I agree with the fuel system diagnosis. Have you changed the fuel filters,
checked the fuel water separator etc.
Fredo

"K. Smith" wrote in message
...
Eisboch wrote:
"Wayne.B" wrote in message
...

On Wed, 25 Jan 2006 00:31:55 +0100, "Steve Lusardi"
wrote:


I think you should identify symtoms,
if you want meaningful help.

It's a 1981 Johnson & Towers marine conversion, supposedly rebuilt
within the last 1,000 hours or so by the previous owner.

My port side engine is taking longer to cold start than it used to,
sometimes needing 8 to 12 seconds of cranking. It used to start on
the first or second turn even when stone cold, and the starboard
engine still does. If it has been run within a day or two it still
starts very quickly. There is very little exhaust smoke at startup
even when cold, and what little there is goes away quickly. The
engine is running well and making full power as far as I can
determine.



There's a guy at our marina who had a somewhat similar problem for a
couple of years. Turns out he had a very small air leak in the fuel
supply line for one engine. It would run fine after starting, (I assume
because the leak was overcome by fuel, but that is pure speculation), but
was hard starting.

Ain't boats fun?

Eisboch (grandkid #5 is a girl!)



Hi again, you say it's making full revs??? a fixed pitch prop is an
excellent dynomometer so if it were seriously down on compression I think
you'd see it in the top end max revs performance.

I think before you go too much further you might check the fuel supply
especially as you say it starts easier after a day, but by then it's well
cold so any mechanical defect in the compression etc would still be there.

Seems granddad Eisboch is on the trail here (he's having a good
day???:-)), fuel filters are a good source of air leaks also. It might be
slowly allowing the fuel to go back down the lines & air in.

These engines as with many Cummins, don't have an injector pump in the
commonly known sense, they have a moderately pressurised fuel rail not
unlike the one in your petrol car. Along this rail (they call it a fuel
manifold in the manual) the unit injectors are sited. There is a
restriction in the fuel rail outlet to maintain feed pressure to the unit
injectors, if the fuel rail isn't properly pressurised by the gear pump
supply it won't start ......... easily. The injectors are driven by the
camshaft & rocker arms the same as the valves are & do the final pressure
increase & injection all in the one movement (pump injector combination).

You can imagine if your fuel system, the gear fuel rail pressure pump as
mentioned (which is also the lift pump usually), the fuel rails & the unit
injectors themselves, get any air in there it will need a few turns to
pump it through & clear it. Once started they can live with a tiny
airleak becasue it just goes straight through the system & out the return
line.


K

Wayne.B wrote:

On Wed, 25 Jan 2006 00:31:55 +0100, "Steve Lusardi"
wrote:


I think you should identify symtoms,
if you want meaningful help.


It's a 1981 Johnson & Towers marine conversion, supposedly rebuilt
within the last 1,000 hours or so by the previous owner.

My port side engine is taking longer to cold start than it used to,
sometimes needing 8 to 12 seconds of cranking. It used to start on
the first or second turn even when stone cold, and the starboard
engine still does. If it has been run within a day or two it still
starts very quickly. There is very little exhaust smoke at startup
even when cold, and what little there is goes away quickly. The
engine is running well and making full power as far as I can
determine.


Change the fuel filter, and if that doesn't help, look for a leak in
your supply lines.

--
"A prudent man foresees the difficulties ahead and prepares for them;
the simpleton goes blindly on and suffers the consequences." - Proverbs 22:3

On Tue, 24 Jan 2006 18:59:06 -0600, dazed and confuzzed
wrote:

look for a leak in
your supply lines.

Any advice on how to do that?

"Wayne.B" wrote in message
news
On Tue, 24 Jan 2006 18:59:06 -0600, dazed and confuzzed
wrote:

look for a leak in
your supply lines.

Any advice on how to do that?



Thinking about it, why not just fire up the hard starting engine then, using
a small container of fuel and an acid brush or similar, lightly wet each
fitting on the fuel lines from your Racors forward to the last fitting you
can get to on the engine. Watch for *suction*. Sort of the opposite of a
pressure bubble test for leaks. I don't know if this would work, but it
might. Or, talk to someone who, unlike me, knows what he is talking about.
:-)

It seems logical though that if that engine is otherwise running fine, you
are getting your RPMs and you are not producing smoke more than the other
engine, that a compression problem due to rings or valves is not likely.

Eisboch

Wayne,
This is simple. You have fuel feed leakdown on that engine. On the detroits,
you have a gearpump that draws fuel from the tank and pushes the fuel
through a strainer and then a filter. From the filter it enters the Cylinder
head where it passes through a cast feed log. Unused fuel is turned around
and again passed through the return log in the head. From there it is
returns heated to the tank. Fuel pressure at the out side of the pump should
be about 45 lbs. Your problem is that the feed line to the inlet of the pump
is draining back to the tank. Probably a very small leak in that line.
Steve


"Wayne.B" wrote in message
...
On Wed, 25 Jan 2006 00:31:55 +0100, "Steve Lusardi"
wrote:

I think you should identify symtoms,
if you want meaningful help.

It's a 1981 Johnson & Towers marine conversion, supposedly rebuilt
within the last 1,000 hours or so by the previous owner.

My port side engine is taking longer to cold start than it used to,
sometimes needing 8 to 12 seconds of cranking. It used to start on
the first or second turn even when stone cold, and the starboard
engine still does. If it has been run within a day or two it still
starts very quickly. There is very little exhaust smoke at startup
even when cold, and what little there is goes away quickly. The
engine is running well and making full power as far as I can
determine.

"Steve Lusardi" wrote in message
...

Wayne,
This is simple. You have fuel feed leakdown on that engine. On the
detroits, you have a gearpump that draws fuel from the tank and pushes the
fuel through a strainer and then a filter. From the filter it enters the
Cylinder head where it passes through a cast feed log. Unused fuel is
turned around and again passed through the return log in the head. From
there it is returns heated to the tank. Fuel pressure at the out side of
the pump should be about 45 lbs. Your problem is that the feed line to the
inlet of the pump is draining back to the tank. Probably a very small leak
in that line.
Steve



Wayne, I might add that the guy with the similar problem that I mentioned
before also had DD671s, FWIW

Eisboch

On Thu, 26 Jan 2006 04:50:08 -0500, "Eisboch" wrote:

Wayne, I might add that the guy with the similar problem that I mentioned
before also had DD671s, FWIW

Thanks, do you happen to know how he located the leak?

On Thu, 26 Jan 2006 10:00:09 +0100, "Steve Lusardi"
wrote:

This is simple. You have fuel feed leakdown on that engine. On the detroits,
you have a gearpump that draws fuel from the tank and pushes the fuel
through a strainer and then a filter. From the filter it enters the Cylinder
head where it passes through a cast feed log. Unused fuel is turned around
and again passed through the return log in the head. From there it is
returns heated to the tank. Fuel pressure at the out side of the pump should
be about 45 lbs. Your problem is that the feed line to the inlet of the pump
is draining back to the tank. Probably a very small leak in that line.
Steve

Thanks, good description. I think I'll start by replacing the engine
mounted fuel filters and gaskets since there seems to be a consensus
that the problem is somewhere in that area. The fuel tanks are 75%
full right now which puts the fuel level above the engines, so that
should rule out an issue with the Racors if I understand this
correctly.

Wayne,
One more time, you have a leak on the SUCTION side of fuel pump. Hint, just
change the hose!
Steve

"Steve Lusardi" wrote in message
...
Wayne,
This is simple. You have fuel feed leakdown on that engine. On the
detroits, you have a gearpump that draws fuel from the tank and pushes the
fuel through a strainer and then a filter. From the filter it enters the
Cylinder head where it passes through a cast feed log. Unused fuel is
turned around and again passed through the return log in the head. From
there it is returns heated to the tank. Fuel pressure at the out side of
the pump should be about 45 lbs. Your problem is that the feed line to the
inlet of the pump is draining back to the tank. Probably a very small leak
in that line.
Steve


"Wayne.B" wrote in message
...
On Wed, 25 Jan 2006 00:31:55 +0100, "Steve Lusardi"
wrote:

I think you should identify symtoms,
if you want meaningful help.

It's a 1981 Johnson & Towers marine conversion, supposedly rebuilt
within the last 1,000 hours or so by the previous owner.

My port side engine is taking longer to cold start than it used to,
sometimes needing 8 to 12 seconds of cranking. It used to start on
the first or second turn even when stone cold, and the starboard
engine still does. If it has been run within a day or two it still
starts very quickly. There is very little exhaust smoke at startup
even when cold, and what little there is goes away quickly. The
engine is running well and making full power as far as I can
determine.