I have a 1999 Chevy Silverado 1500 4.8ltr engine..the engine runs but then dies after a few minutes. Also when its cranked there is a strong smell of gas. I hooked it up to a computer, was given the code P0452. Don't know what this is or how to fix it...any help would be appreciated. Thanks

GM has had problems with deposits on the
ends of the fuel injectors. While checking
ohm readings they read ok, but the correct
amount of fuel cannot be distributed to the
cylinder. GM has a tsb for rough idle on cold
start up for this vehicle, but I have also
seen it while warm. I would perform the
injector flush they say to do. Gm has a
special flushing fluid to remove these
deposits. Here is the tsb.
File In Section: 06 - Engine/Propulsion
System
Bulletin No.: 00-06-04 -003B
Date: February, 2003
TECHNICAL
Subject:
Rough Idle After Start, And/Or A Service
Engine Soon (SES) Light
(Unstick And Clean Central Sequential Fuel
Injection (CSFI) Poppet
Valves or Convert to MFI)
Models:
1995-2002 Chevrolet and GMC S/T Models
1996-2002 Chevrolet and GMC C/K, M/L, G,
P Models
1996-2001 Oldsmobile Bravada
1999-2000 Cadillac Escalade
with 4.3L, 5.0L or 5.7L Engine (VINS W, X, M,
R - RPOs L35, LF6, L30, L31)
Except 2002 VIN X - RPO LU3 Models
This bulletin is being revised to update the
Warranty Information. Please discard
previous copies of Corporate Bulletin
Number 00-06- 04-003 B with warranty chart
(Section 06 - Engine). This copy is for
Dealers in the state of CALIFORNIA ONLY.
Condition
Some customers may comment on rough
idle after start-up , especially if the vehicle
has sat overnight. These symptoms may be
intermittent. The Service Engine Soon (SES)
light may also be illuminated. Current
misfire or history misfire codes may be
detected with the Tech 2 scan tool.
Cause
A deposit build-up on the CSFI poppet
valve ball and/or seat may cause the poppet
ball to stick open or closed. In either case,
the specific cylinder will be mis-fueled,
resulting in a cylinder mis-fire condition.
Correction
A new injector unsticking and cleaning
process has proven to be effective in
restoring poppet valves to an "as new"
condition. CSFI injector replacement should
NOT be considered as a correction for this
customer concern.
Check the vehicle history to determine if the
vehicle is returning for a second fuel system
repair for this condition. If the fuel system
has been repaired for this condition
previously, then inform the customer that an
alternate fix is available. A new MFI fuel
system has been developed that will back
service the CSFI fuel system. The MFI fuel
system eliminates the CSFI poppet valve ball
and seat. The CSFI fuel system will need to
be replaced as a unit. Refer to Central SFI to
MFI Conversion instructions in this bulletin.
Notice : Individual CSFI injectors can not be
replaced with MFI injectors. The entire CSFI
fuel meter body will need to be replaced.
The bracket used to retain the injectors in
the fuel meter body is different between the
CSFI and MFI unit. The unit may not seal if
you mix injectors. Severe engine damage
could result.
Cleaning the CSFI injectors is the preferred
repair. The CSFI unit should not be replaced
until cleaning has been attempted. If the
vehicle should return for the same repair,
then the CSFI unit can be replaced with an
MFI unit. If the vehicle is out of warranty,
the customer should be given the option of
which fix to pursue.
Important : "GM of Canada" dealers
require District Service Manager approval
prior to replacing the CSFI unit with a MFI
unit under warranty.
The first step of this process is to use the J
41413 Evap Pressure/Purge Station, in
conjunction with the J 44466-10 pressure
regulator/hose assembly, to provide the
required high pressure (150 psi) source to
perform the unsticking procedure. The J
39021 fuel injector tester and accessories
provide the means to "energize" the
injector. Some later model-year vehicles
may utilize the Tech 2(R) to "energize" the
injectors.
The second step of this process is to run the
engine on a solution of 10% Top Engine
Cleaner and 90% gasoline. This will
effectively clean any deposits from the ball
and seats of the poppets. It is very
important that the engine fuel system is
separated from the vehicle fuel system. Top
Engine Cleaner may have detrimental effects
on the fuel pump. GM has had problems with deposits on the
ends of the fuel injectors. While checking
ohm readings they read ok, but the correct
amount of fuel cannot be distributed to the
cylinder. GM has a tsb for rough idle on cold
start up for this vehicle, but I have also
seen it while warm. I would perform the
injector flush they say to do. Gm has a
special flushing fluid to remove these
deposits. Here is the tsb.
File In Section: 06 - Engine/Propulsion
System
Bulletin No.: 00-06-04 -003B
Date: February, 2003
TECHNICAL
Subject:
Rough Idle After Start, And/Or A Service
Engine Soon (SES) Light
(Unstick And Clean Central Sequential Fuel
Injection (CSFI) Poppet
Valves or Convert to MFI)
Models:
1995-2002 Chevrolet and GMC S/T Models
1996-2002 Chevrolet and GMC C/K, M/L, G,
P Models
1996-2001 Oldsmobile Bravada
1999-2000 Cadillac Escalade
with 4.3L, 5.0L or 5.7L Engine (VINS W, X, M,
R - RPOs L35, LF6, L30, L31)
Except 2002 VIN X - RPO LU3 Models
This bulletin is being revised to update the
Warranty Information. Please discard
previous copies of Corporate Bulletin
Number 00-06- 04-003 B with warranty chart
(Section 06 - Engine). This copy is for
Dealers in the state of CALIFORNIA ONLY.
Condition
Some customers may comment on rough
idle after start-up , especially if the vehicle
has sat overnight. These symptoms may be
intermittent. The Service Engine Soon (SES)
light may also be illuminated. Current
misfire or history misfire codes may be
detected with the Tech 2 scan tool.
Cause
A deposit build-up on the CSFI poppet
valve ball and/or seat may cause the poppet
ball to stick open or closed. In either case,
the specific cylinder will be mis-fueled,
resulting in a cylinder mis-fire condition.
Correction
A new injector unsticking and cleaning
process has proven to be effective in
restoring poppet valves to an "as new"
condition. CSFI injector replacement should
NOT be considered as a correction for this
customer concern.
Check the vehicle history to determine if the
vehicle is returning for a second fuel system
repair for this condition. If the fuel system
has been repaired for this condition
previously, then inform the customer that an
alternate fix is available. A new MFI fuel
system has been developed that will back
service the CSFI fuel system. The MFI fuel
system eliminates the CSFI poppet valve ball
and seat. The CSFI fuel system will need to
be replaced as a unit. Refer to Central SFI to
MFI Conversion instructions in this bulletin.
Notice : Individual CSFI injectors can not be
replaced with MFI injectors. The entire CSFI
fuel meter body will need to be replaced.
The bracket used to retain the injectors in
the fuel meter body is different between the
CSFI and MFI unit. The unit may not seal if
you mix injectors. Severe engine damage
could result.
Cleaning the CSFI injectors is the preferred
repair. The CSFI unit should not be replaced
until cleaning has been attempted. If the
vehicle should return for the same repair,
then the CSFI unit can be replaced with an
MFI unit. If the vehicle is out of warranty,
the customer should be given the option of
which fix to pursue.
Important : "GM of Canada" dealers
require District Service Manager approval
prior to replacing the CSFI unit with a MFI
unit under warranty.
The first step of this process is to use the J
41413 Evap Pressure/Purge Station, in
conjunction with the J 44466-10 pressure
regulator/hose assembly, to provide the
required high pressure (150 psi) source to
perform the unsticking procedure. The J
39021 fuel injector tester and accessories
provide the means to "energize" the
injector. Some later model-year vehicles
may utilize the Tech 2(R) to "energize" the
injectors.
The second step of this process is to run the
engine on a solution of 10% Top Engine
Cleaner and 90% gasoline. This will
effectively clean any deposits from the ball
and seats of the poppets. It is very
important that the engine fuel system is
separated from the vehicle fuel system. Top
Engine Cleaner may have detrimental effects
on the fuel pump.