How to remove hard carbon deposits?

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    After my 1988  4 cyl. 3S-FE Camry is driven for a few minutes the
engine loses power.  It is losing fuel pressure   (have gauge
attached). But for the first few minutes it runs fine.  Actually, when
you open the hood and watch the gauge when it has started
malfunctioning,  it's "hunting". At idle, it will rise to about 35
psi, and then go  all the way down to about 15 psi, and repeats the
cycle about once a second. The car will not accelerate when you push
the gas pedal. Will just barely keep running. THought it was the fuel
pump flaking out, (before seeing that wild fluctuation with fuel gauge
attached). So I changed the fuel pump. Still does the same thing. The
pump was in a terrible state of corrosion, so it was not wasted effort
or $$$. I am sure it must be the fuel press regulator now. I removed
it, and the port connecting to the fuel rail was narrowed down to
about 1/8 inch, less than half of the unobstructed diameter! Looks
like black carbon deposits. That deposit was  easy to remove...but I
suspect that the valve stem and seat inside probably has as much
carbon buildup, and it might be making the valve stick, which will
certainly cause a wild oscillation like this.  A new press regulator
costs $80 and I am kind of out of more $$$ for parts right now. The
diaphragm is not ruptured. You can't dissasemble it to clean the valve
seat and stem. So is there a product that will dissolve the deposits
from 18 years of gas flowing through it?

Re: How to remove hard carbon deposits?

<geronimo> wrote in message
So is there a product that will dissolve the deposits
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Identifying those deposits better would help a lot::
 -  only gasoline had been flowing through this port, I am not sure carbon
would be your most likely diagnosis...

By-products of the corrosion you found in the fuel pump would seem more
likely.  And for there to have been extensive corrosion, it would follow
that water, or another electrolyte or corrosive fluid, must have been
present at some time, or even over a long period of time.

If I could get the part out, and if I had a friend or acquaintance who had
to an ultrasonic cleaner, I might try that first.  (Labs, jewelers,
universities, etc sometimes have these.  Ultrasonic waves knock off the
deposits without the use of chemical cleaners.)

If you can get a small piece of the black deposit and heat it in a flame
from, say,
a propane torch or even an oven range burner, this will tell you something
of the
chemistry.  If it burns completely, it may be carbon or something totally
If it does not burn completely, but changes color, melts, etc.  that may
give you a
better clue.

Let us know a little more if possible.

Re: How to remove hard carbon deposits?

Daniel suggested a steam cleaning method for valve deposits that caused
excessive clearances. An interesting method but haven't tried it or
needed it (regular use of a Tier 1 detergent gas). But here is the

From:        Daniel - view profile
Date:        Thurs, Apr 13 2006 9:42 am

Yes, I have a suggestion. Don't pull the heads just yet.
If you're showing .036" clearance instead of .012 and couldn't even
purchase a large enough shim, I suspect something else is going on.
My guess - just a guess, but I'd try this first, is that you have
carbon built up on the valve faces from the prior owner perhaps idling
excessively or never getting the engine up to high speed for 200,000
Normally I would recommend Red Line complete fuel system cleaner,
because it gently and safely and continuously removes carbon - but it
takes a long time, like up to 10,000 miles, and you say you're just
fixing up the car for a quick sale.
So here's my recommendation.
There's an old mechanics trick that many people hold in high regard.
Actually you have two choices.
Seafoam or distilled water.
You can find Seafoam on the Internet or at NAPA stores and I think I
also saw some at AutoZone. Seafoam was developed to clean outboard two
stroke boat engines fouled with carbon and reportedly does a great job.
Just follow directions. Something like pour it into the intake on a
fully warmed engine at fast idle until the engine dies then let it sit
for around 10 minutes. Then restart and ignore the immense cloud of
billowing smoke at the exhaust, and drive the car until the smoke
clears up.
Method two is using plain water, which people have said works equally
well without the smoke. Seafoam's MSDS sheets show light oil and naptha
and despite their claims wasn't entirely persuaded this is completely
safe for the O2 sensor, whereas with plain water, no contamination
Same idea, with the engine hot at fast idle slowly pour water into the
intake, keeping the engine from stalling, probably a little less than
one quart.
If you have a lot of carbon build up, be careful about overheating the
catalytic converter. Some have said it can glow orange or red from
being overloaded with the exiting carbon - but they're designed to
operate at high temperature, so should be no harm, just let it cool a
while afterwards. Others have said they found a small pile of carbon
below the tail pipe afterward.
Caution: Note well --- do_not_ pour water too quickly because there is
a risk of "hydrolocking" the engine if you flood it with water filling
the cylinders with an incompressible liquid you can do engine damage --
so just trickle the water in slowly and there is no risk of hydrolock.
You are essentially steam cleaning the engine, and supposedly you are
cleaning it chemically as well it is said the carbon in the engine
combines easily with the oxygen in the water.
So by either method you should wind up with combustion chambers that
are "squeaky" clean.
I found the easy way to inject water into the throttle body, was to use
a garden sprayer I had in the garage. Had a translucent plastic two
gallon bottle with a pump to pressurize and then spray through a
nozzle, so I just sprayed a small stream of water into the intake and
white steam came out the exhaust. The catalytic converter did not
overheat, and I did not find any carbon at the tail pipe, but had
already been using Red Line, and valve clearances were in spec.

geronimo wrote:
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Re: How to remove hard carbon deposits?

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Maybe I misunderstood his post.  I understood the black deposits to be
in the fuel rail or regulator port.  This is why I questioned carbon

If it is carbon (as is often seen in the plenum area, etc), then please
my questions.

Re: How to remove hard carbon deposits?

If not carbon, then what other impurities can precipitate out of
gasoline? The hard black deposits (which must have been impurities in
the fuel) that were narrowing the port that connects directly to the
fuel rail I was easily able to remove with a scribe. Now the
controller port is clear again.  But its * inside*  the assembly---
where the valve actuator stem and valve seat are---that I cannot get
to! I can pour Berrymans carb cleaner down into this port and it
doesn't leak out, I guess with no vacuum on the presure controller,
the valve is closed.  I see there is another Berrymans product
specifically for cleaning deposits from fuel injectors. I can imagine
undiluted injector cleaner would be pretty potent!  Maybe if I let it
sit in a jar of this stuff for a day or two, the deposits on the
internal valve stem and seat will dissolve?

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Re: How to remove hard carbon deposits?

There is a better method than just a simple pour-and-go for things like
Seafoam, Marvel Mystery Oil, and such.
My method for Seafoam is rather extensive. Ready for it?

Go and buy 4 cans of SeaFoam. Best price I've seen is at Advance Auto Parts.
This is a driveway method.
With your tank around 6 gallons (typically about half in most cars) pour a
full can into the tank. Drive the car about 1 mile, then allow to idle for a
few minutes, then kill it. Take the other can, and find the best place to
pour the liquid. The throttle body or carb is typically best, but anything
that flows evenly to all cylinders will do. After about 15 minutes of cooling,
fire it up again. Begin SLOWLY pouring in the SeaFoam. The engine will
stumble, but do not let it die just yet. If you need to, manipulate the
throttle a bit to keep it alive. When about 1/4-1/2 of the can (depending on
engine size. More for big 454 V-8's, less for 1.5L I-4s) is in the engine,
pour enough to kill it. Allow it to sit for about 1/2-1 hour. After it has,
fire it up. It will likely be flooded, so do what you must, BUT DO NOT REV IT
JUST YET. Allow to idle for 20-30 seconds, then floor it. Rev it from idle to
4 or 5,000 RPM. After a few bounces, maintain 2500RPM for 15 seconds. You
will be visited by a dark greyish cloud that ranges from annoying to the
firetrucks showing up. Drive the car around for a mile or 2. Idle for a few
minutes, then shut fown for 15. Repeat for the last half of the can of Sea-
Foam. After this is done, drive the car to as low as you dare, then pour in a
can of Seafoam and top it off. Save the last can for your next tank. This
method will blow away dang near any carbon that can be removed without a wire
The water method typically involves closer to 2 quarts of water, but it is
very important to do it slowly. With this method, try to keep the car running.
After you've done as much water as you want to (a pint will help, but 2
quarts will blow away) drive the car until all steam stops. Otherwise you'll
have water in your oil rusting your block inside and water in the exhaust
rusting it out.

Catalytic converters are designed to run hot, but not too hot. Overheat a
catalytic converter and the element inside begins to melt, blocking flow, and
if hot enough, will cause a fire.

Re: How to remove hard carbon deposits?

<geronimo> wrote in message
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If you have had corrosion in the gas tank and gas pump, then impurities,
not necessarily soluble in gasoline, can form.  The particle size can be so
that they can actually penetrate filters and precipitate on down the line.
particles are called 'colloidal' and are extremely small.

Some possibilties include:
Iron oxide (magnetite)...a black iron oxide compound, from the gas tank
Tin oxide .........................from attack of the terneplate gastank by
alcohol or water
Lead oxide.......................same as terneplate
Rubber particles.............from decomposition of elastomers, packings,
rubber parts

There are a lot of possibilities.. Carbon would possibly be an easier answer
than some
of the others.

Re: How to remove hard carbon deposits?

Actually, I was referring to his "valve stem" part of the message. But
if its in the fuel rail, I wonder if the fuel filter should have gotten
it. Unless it's the part of fuel hose after the fuel filter
disintegrating from the inside to give black carbon like deposits.

Re: How to remove hard carbon deposits?

<geronimo> wrote in message
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Have you checked the exhaust is clear, specially the cat converter?

Re: How to remove hard carbon deposits?

 Black deposits in the fuel line are varnish not carbon. But even with
the restriction I will bet that you get enough gas to run, more than
enough. You can measure output into a can. But your description of
running fine cold is a description of a secondary electric issue such as
a bad coil not fuel. Idleing fine but not getting power or bogging is
exactly what a shorting coil did for me for 3 years, it started, ran
till motor reached full temp then it would not move when stopped, it
would even rev up, but under the load needed to ignite enough gas to
move the car it would even stall the motor. A bad plug wire will do this
to a cilinder, 2 bad wires to 2 cilinders and bad coil to all 4. The
camrys of many years in that era are now experiancing this, shorting
coils, a common issue. Since the coil is covered you cant see it short.
Im not sure your real issue is fuel related at all, a coil is cheap and
easy to replace compared to what you are doing with the fuel system. I
would not say it is electrical if it had not been my same issue
undiagnosed for years and the same ive seen as a common Camry issue that
a new coil fixed.  Remember its fine cold, even 15lb should accelerate
the car hot, maybe not fully-full throttle, but not making it
undriveable. I still bet your issue is electrical, a mechanic with a
scope would prove this instead of you guessing and parts changing

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