2007 Trailblazer SS starting issues

#1
I have a starting issue on my 2007 trailblazer SS LS2 engine. Once the car is running everything is good. No rough idle. Engine runs smooth. I turn the engine off and wait 5 min ( or 2hr). Then try to restart and it takes 5-6 cranks to start. I attached a fuel presser meter to the fuel rail. The fuel pressure is 55 to 60 psi. Turn the engine off the fuel pressure goes to zero. Should the pressure stay up when the engine is off? Do you think it is a fuel pressure regulator issue?
 

MRRSM

Lifetime VIP Supporter
#2
Ordinarily... the Fuel Pressure Ball-Check Valve or Device would be present on the Out-Flow side of the Fuel Pump. So after shutting down the Engine (With an Analog Fuel Pressure Gauge in place at the Engine...) If the Fuel Pressure Drops suddenly to "0"... the issue is probably within the Pump itself. However... if the Bleed Off Pressure diminishes more slowly... you can suspect either one or more stuck EFIs ...or a Bad Fuel Pressure Regulator.

If you are getting any Codes related to Mis-Fires... and you can 'sneak out' the suspect EFIs on those cylinders ... look for signs of congealed fuel residue that bakes on at the very bottom of the Injector Spinnerets. This is caused by the slow leak of fuel eventually boiling off from residual engine heat and leaving a tell-tale dark brown ring. Also... the presence of Fresh Gasoline on those related Cylinder Spark Plugs that appear soaking wet would indicate EFI leaks as well.
 
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JOE60ISH

JOE60ISH

New Member
#3
Ordinarily... the Fuel Pressure Ball-Check Valve or Device would be present on the Out-Flow side of the Fuel Pump. So after shutting down the Engine (With an Analog Fuel Pressure Gauge in place at the Engine...) If the Fuel Pressure Drops suddenly to "0"... the issue is probably within the Pump itself. However... if the Bleed Off Pressure diminishes more slowly... you can suspect either one or more stuck EFIs ...or a Bad Fuel Pressure Regulator.

If you are getting any Codes related to Mis-Fires... and you can 'sneak out' the suspect EFIs on those cylinders ... look for signs of congealed fuel residue that bakes on at the very bottom of the Injector Spinnerets. This is caused by the slow leak of fuel eventually boiling off from residual engine heat and leaving a tell-tale dark brown ring. Also... the presence of Fresh Gasoline on those related Cylinder Spark Plugs that appear soaking wet would indicate EFI leaks as well.
Yes the Fuel pressure drops suddenly within 2-3sec. I'm not getting any engine code. I do not smell gas at all. I was going to add a fuel check value in the supply side to see if it fixes the issue. If it fixes it,I know it is the fuel pump. Then I can replace the pump. Thanks for the info
 

MRRSM

Lifetime VIP Supporter
#4
Please make certain that whatever device it is that you use as an intermediary to take up this job is Pressure Rated at or above 60 PSI and likewise... that the type and arrangement of really good Fuel Hose Clamps get used when it gets installed.
 
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JOE60ISH

JOE60ISH

New Member
#5
I could not find a good spot to put a check value. I replace the fuel pump and that fix my starting issue. Thanks for the help.
PS
I did find very good fuel check values at JEGS.com
 

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