Diagnostic Tips For Direct Injected Engines Hard Start Cold – 2008-2020 Buick Cadillac Chevrolet GMC Saturn

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Bulletin No.: PIP5180C Published date: 07/28/2020
Preliminary Information
PIP5180C Diagnostic Tips For Direct Injected Engines Hard Start Cold
Models

Brand: Buick

Model: Enclave

Model Years: 2009 – 2020

VIN:
from to
All All

3.6 LFY, 3.6 LLT

Engine:

Transmissions: All

Buick Buick Buick Cadillac Cadillac Cadillac Cadillac Cadillac Chevrolet Chevrolet Chevrolet
Chevrolet Chevrolet Chevrolet GMC GMC
Saturn

LaCrosse Regal Verano ATS, ATS-V CTS, CTS-V STS
SRX XTS
Camaro Caprice PPV Captiva Sport Equinox Impala Traverse Acadia Terrain Outlook

2010 – 2016
2011 – 2017
2012 – 2017
2013 – 2019
2008 – 2019
2008 – 2010
2008 – 2016
2013 – 2019
2010 – 2020
2012 – 2014
2012 – 2014
2010 – 2020
2012 – 2020
2009 – 2020
2009 – 2019
2010 – 2020
2009 – 2010

All All All All All All All All All All All All All All All All All

All All All All All All All All All All All All All All All All All

2.4 LAF, 2.4 LUK, 3.0 LF1, 3.6 LFX, 3.6 LLT
2.0 LHU, 2.4 LAF, 2.4 LEA, 2.4 LUK
2.0 LHU, 2.4 LEA
2.0 LTG, 2.5 LCV, 3.6 LFX, 3.6 LF4
2.0 LTG, 3.0 LF1, 3.6 LF3, 3.6 LFX, 3.6 LLT
3.6 LLT
2.8 LAU, 3.0 LF1, 3.6 LFX
3.6 LF3, 3.6 LFX
2.0 LTG, 3.6 LFX, 3.6 LLT
3.6 LFX
2.4 LEA, 3.0 LFW
2.0 LTG, 2.4 LAF, 2.4 LEA, 3.0 LFW, 3.6 LFX
2.5 LKW, 3.6 LFX
3.6 LFY, 3.6 LLT
2.5 LCV, 3.6 LLT
2.0 LTG, 2.4 LAF, 2.4 LEA, 3.0 LFW, 3.6 LFX
3.6 LLT

All All All All All All All All All All All All All All All All All

Supersession Statement
This PI was superseded to update Model Years and refer to 19-NA-044. Please discard PIP5180B. The
following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition / Concern
Hard start, extended crank, or excessive black smoke from the exhaust when starting.

NOTE: Prior to proceeding with the diagnostics in this PI ensure the concern is not covered in the
latest version of 19-NA-044 showing normal conditions with these engines.
A comparison to a known good vehicle is also recommended.

NOTE: A button push or key turn to start to event time out is not a “NORMAL” condition on any of
these vehicles.
Recommendations / Instructions

Basic Tests:
Verify Fuel Quality?
Spark Test with ST125, if a coil issue is suspected then follow Ignition System Diagnostics.
Perform a Compression Test.
You should see 150-185 Average Compression, no cylinder should be less than 140 psi on a HFV6
engine non turbo charged.
You should see 170-200 Average Compression, no cylinder should read less than 100 psi on the 4
cylinder engine or turbo charged HFV6.
If the condition is a “Hard Start Cold” only, and you suspect that you may have a carbon issue
causing a valve to stay open, follow the latest version of 16-NA-383 and perform a cold compression
test.
Also install a vacuum gauge prior to cold start and watch needle for signs of a sticking valve.
Fuel System Check:
*Follow all these steps in order.
The following tests should be done after an overnight cold soak.
Set your vehicle up with the CH 48027 digital pressure gauge and J37287 fuel line with shut- off
valve.
Run vehicle to purge all air from fuel system and then shut vehicle off and let sit overnight.
Unplug the injector harness connector.
Next Morning:
Key On and do not start engine – Using a CH 48027 Digital Pressure Gauge, verify “Key On” engine
off, prime pulse fuel pressure should be between 55-60 psi. Record reading.
This test will confirm correct operation of the in-tank fuel pump assembly.
Use your Tech2 or GDS set in PSI to also confirm what the Fuel Rail Pressure Sensor is reading as
this should always be close to what your Digital Fuel Pressure Gauge reads for low side pressure
during this test.
This will also confirm if there is an off-set with the Fuel Rail Pressure Sensor. Next you will crank
the engine to see if it fires.

With the injector harness connectors unplugged, the injectors are now electrically disabled so no
fuel should be delivered to the engine.
When cranking over the engine, if engine fires this means that one or more injectors have been
leaking and have introduced fuel into one or more cylinders.
Reconnect the injector harness connectors and start the engine, let the vehicle run for ten minutes
and then shut vehicle down.
You will now close the shut-off valve in the J37287 Fuel Line, which will now separate the engine
side of the fuel system from the rear section of the return- less fuel system.
Using the CH 48027 Digital Pressure Gauge, look for a drop in the high side of the fuel system, by
monitoring low side pressure.
With the J37287 valve closed, the system should hold at least 60 psi for a few hours.
If you see a rapid decrease in fuel pressure, this would indicate a leaking High Pressure Fuel Pump
or leaking injectors since the fuel pressure cannot bleed off to the tank as your J37287 valve is
closed.
All this is assuming that your gauge is good with no leaks or any leaks at the Schrader valve.
Warranty Information
The correction for this concern may be one of several repairs described in the diagnostic tips
above.
For vehicles repaired under warranty, please use the appropriate warranty labor operation based on
the actual cause and repair.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition
exhibited is resolved without completing every step, the remaining steps do not need to be
performed.

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