Hi everyone and thanks for looking. I need some pro opinions here I've found myself mystified by this issue I'm having.


Little background first:

• 1999 Chevy Blazer 4X4 W engine code
• Fuel pump replaced last year (Delphi)
• Fuel filter done

When all of this started I was getting the classic signs of spider injector leakage as the truck kept flooding itself. It flooded BAD BAD probably 5 times before I could get time to work on it. I had to use quick start to get the thing to start as it was flooded so bad... when it eventually would start it would run on like 4 cylinders for a minute or so until it would come back to life.

• Changed spider injectors with the upgraded MPFI design
• That of course includes a new fuel pressure regulator in the unit
• Changed oil fearing gas got in it
• Changed spark plugs and wires
• Changed distributor cap and rotor
• Changed PCV valve
• Cleaned throttle body very well

So after all of that you would think it would be running great... but no. For the most part it starts ok but it's weird sometimes it's trying to start of the first or second starter crank instead of waiting for the normal cranks to start (5 maybe? Hope you know what I mean here) and of course it sputters because it tried to start too quickly, then it's fine.


Next is the idle - it is idling horribly, missing etc...gas mileage is horrific I'm getting 250 km to a tank! It accelerates fine, smooth, would never know there is an issue until it idles! Has power etc.

• Did the soapy water spray test... no arching... cannot find any vacuum leaks

I bought an ODBII Bluetooth dongle off eBay and bought the Torque program as I had a check engine light come on. Good 'ol P0420 code bank 1 catalyst low efficiency.


Any ideas here? My thoughts are - from all of that flooding could the O2 sensors have gone on me? Does that even make sense for a starting problem or idle problem?


The Torque program allows you to see the O2 voltage readings live but I'm not sure what I'm looking for. It shows a graph and it looks like the readings should go up and down smoothly but they aren't. I ran a test with the tool on the O2 sensors and this is what came out (I have no clue what this means!):


Mode $06 report generated by Torque for Android
================================================

Vehicle VIN: Not present
Vehicle Manufacturer: Unknown
Vehicle Calibration ID: Not present

Unit and scaling information are not supplied with the data from the ECU for this type of vehicle. Consulting the manufacturers service book for this information is recommended.

Test report:
------------------
TID:$02 CID:$04
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$10
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$11
- Lean to Rich sensor threshold voltage(constant)
Min: 375
Test result value: 376
PASS
----
TID:$02 CID:$12
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$20
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$26
- Lean to Rich sensor threshold voltage(constant)
Max: 70
Test result value: 65,530
FAIL
----
TID:$02 CID:$30
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$31
- Lean to Rich sensor threshold voltage(constant)
Max: 120
Test result value: 65,530
FAIL
----
TID:$02 CID:$36
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$40
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$46
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$06 CID:$35
- Lean to Rich sensor switch time(calculated)
Max: 95
Test result value: 27
PASS
----
TID:$06 CID:$47
- Lean to Rich sensor switch time(calculated)
Max: 212
Test result value: 46
PASS
----
TID:$06 CID:$55
- Lean to Rich sensor switch time(calculated)
Max: 85
Test result value: 43
PASS
----
TID:$07 CID:$0c
- Minimum sensor Voltage for test cycle(calculated)
Max: 0
Test result value: 56,320
FAIL
----
TID:$07 CID:$0d
- Minimum sensor Voltage for test cycle(calculated)
Max: 155
Test result value: 63,431
FAIL
----
TID:$0c CID:$20
- Misfire counts for last/current driving cycles(calculated)
Max: 0
Test result value: 47
FAIL
----

End of report.


Only other thing is I smell gas back by the tank. I think it's my fault I used to top up the tank and I read later that on these trucks that will fill the charcoal canister with raw fuel...ooops FML. Is this a concern? Do I need to change this canister and does or can it affect how the truck is running?

Please help!!! Thank you!!!

 

First need to find out if it's getting too much fuel, or if there's a problem with ignition. This thread explains how to test fuel delivery: https://blazerforum.com/forum/2nd-ge...eakdown-88305/ Post both sets of numbers and we can analyze it for you.

 

Hi captain thank you. I went and bought a pressure tester. At the service port with the engine off turn key forward it spikes to max 58psi then something in the engine bay clicks and it immediately drops to 50-52psi. With the engine running, the needle bounces quickly back and forth between 48psi and 50psi at idle. If I Rev to 3000 rpm it's at 47psi and jog the throttle it will go to about 50psi.

For the leak down test I shut the engine off and it was just north of 50psi then the pressure rose to 54psi during and fell to 52psi at the 10 minute mark. What is going on here!?

Im not sure when I will be able to get the 2nd max test done...little more involved.

 

There is definitely a fuel delivery problem. Key on, engine off, fuel pump running, is too low, and leakdown to 50-52psi is excessive. There are no engine running fuel pressure specs for this system, far too many variable involved. The 4psi rise is due to engine heat, (normal with a hot engine). Best to check it cold to avoid that and give a more accurate reading. Don't bother though, we already know there's a bigger issue somewhere


When checking pressure and leakdown at the service port, it gives the LOWER of regulated pressure, and fuel pump maximum output pressure. If the pump can only build 58psi, you'll never know what regulated pressure is. This is why we need pump max output pressure & leakdown to make a diagnosis.

 

Makes sense...isolate the fuel pump and run another test. It's supposed to be nice out tomorrow (Ontario, Canada...unpredictable this time of year ) so I will try to get to the pump. No access to a hoist tho

 

Exactly, the pump needs to be isolated. There is a list at the bottom of the link in post #2. It includes part numbers for the necessary items you'll need to do the test. Don't need a hoist, but it helps if you jack it up a bit

 

Cool thanks. I'd hate to think a Delphi pump is gonzo after 6 months...sigh

 

--it happens

 

Just to be sure - when I turn the key forward the fuel pump runs for a second or two and stops. When it's done running and the system is pressurized, at this point I should be seeing 60-66psi? Tx

 

In the link it explains. With your 1999, there is a vacant terminal in the underhood fuse panel. Apply battery voltage to it and check pressure while the pump is running. Do this for both test locations. When you check pressure, the pump must be running. When you remove voltage from the terminal, wait 10 minutes and see what the pressure is.