New here with my DOA '99 Burb

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efrice

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Hey everyone. Another newbie here to the forum.

I bought my '99 new from the dealer and have done all of the maintenance and some heavier work on it over the years.

Now there's a mystery. I put a little gas in and forgot to close the cap. A few miles later it died and the only codes I have are P0420 & P0430 and have been active for quite a while.

It cranks a little rough. Any ideas?

Thanks, Eric
 
Both codes point to the catalytic converter. Try disconnecting the exhaust before the converter and see if it will start.
 
Agree with Zora -

Here's the code detail:

DTC Code: P0420

Description: Catalyst System Efficiency Below Threshold Bank 1

Probable Causes:

- Sensor or solenoid faulty
- Connector terminal contact is damaged or corroded
- Wire harness - Check harness for correct voltage, open, short to ground or short to voltage
- Update control unit software - Check for the latest control unit update
- Powertrain or Engine Control Module faulty
- HO2S sensor contamination/damaged
- Exhaust leaks or restrictions
- Catalytic converter damage
- Catalytic converter improper operation

My first thoughts were catalytic converter, vacuum leak, bad HO2 sensor(s). The codes that were set are both the same - one is for Bank 1 and the other Bank 2 for the exhaust. Because this happened on both banks I would rule out the HO2 sensors because I would doubt that you would have multiple failures on the sensors at the same time.

Do you have a OBD II scanner or have access to one?

If so you could check the function of the HO2 sensors.

Another check for the CAT is to use a infrared thermometer on both CATs to make sure they're getting up to temp - IIRC they should operate in the 1200-1600 F range - they start working at about 600 F and at 2000 F they start to have problems. So, temps below or above the ideal range could indicate a problem inside the cat. If the CATs are operating at the right temp then that should rule them out.

You could also pull your NEG battery cable for 15 mins and let the codes get deleted and then run it again and see if they get set again.

Since you say it happened after you forgot to replace the gas cap I'm thinking that it might have just gotten a bad vacuum reading and either it still has a vac problem or the codes just need to be reset.

After you do some checks let us know what you find and that will help narrow it down - good luck.

ADD:

Here's a decent link to CAT failures - http://auto.howstuffworks.com/question482.htm

And a really good video on CAT diagnosis - http://www.youtube.com/watch?v=9VZ5K8n5jj0
 
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Want to clarify something you say it died, are you saying at this point the vehicle will not start? If so my thought was a clogged converter.
 
Thank you, Spriteman.

This gives me more to go on. I'll try the neg battery cable first, being the easiest one.

I do have a a code reader, an Innova 3100a made by CanOBD2. It has some details for each code, but it's all Greek to me. I've attached screen shots of the codes. There are 3 codes:

1. The first is P0430 and has FF data included with it.
2. The second is P0420 with no FF data.
3. The third is also P0420 with "Pending" at the top of the screen and no FF data.

If you can help me interpret them, I'd be grateful.

On a different note, could it possibly be a timing chain? How would I test for this?

Eric
 

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Good catch Zora - I hadn't noticed that it wasn't running - I read it as hard to start but would start eventually.

I guess we had better start from the beginning since the CAT may just have been the result of some other problem. I've not known a vehicle to no-start with a CAT problem. I don't think the PCM even starts interpreting HO2 info from the CAT until it reaches a certain temp.

Have you tried starting since the engine has gotten cold?

So, need to check spark at each cylinder - then check for fuel pressure at the fuel rail.

Are there any other codes set?

Let us know the results of these tests and we can go from there.
 
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Hey Spriteman,

There are no other codes. I disconnected the neg terminal for 30 minutes, but the codes remain.

Update -

I disconnected both exhaust connections at the manifold and it still won't start.

Next I poured a little gas into the carb and it fired right up, but won't keep running. The fuel filter is new and the fuel pump "sounds" like it is pressurizing. The tank is 1/4 full.

How would I distinguish between a faulty fuel pump and a faulty fuel pressure regulator?

Eric
 
2 Tests -

1 - Carefully remove the small vacuum line on the fuel pressure regulator and see if there is any gas or signs of gas in the line. If there is then you have a bad FPR.

2 - Attach a fuel pressure tester to the schrader valve on the fuel rail and see if you get a 30-50 psi there. If so, then the fuel pump is probably good - not absolute but probably.


BTW - you can borrow a fuel pressure tester from an Autozone type parts place - you could probably test it while you're there.
 
Spriteman,

I'm not as advanced in my knowledge as you and others.

Where would I find the fuel pressure regulator?

What is a schrader valve, fuel rail and where would I locate these?

Thanks for your patience with this apprentice...

Eric
 
Ah - no biggie - let's see if I can find some pics that will help you get your bearings.

Okay - check out this link - http://parts.nalleygmc.com/showAssembly.aspx?ukey_assembly=371985&ukey_make=1024&ukey_model=14543&modelYear=1999&ukey_category=19485&ukey_driveLine=6218&ukey_trimLevel=14208


I looked up your part for a 1999 Chevy Burb 2WD 1500 LS - the setup for your vehicle should be the same if this isn't your exact trim. If this is NOT your setup then let me know and we'll track down some better diagrams. If you want to private message your VIN that will make it easier to nail that down.

All of these parts are below where the airbox connects to the throttle body.

Part numbers 9-13 are the fuel pressure regulator parts - the port on #9 is where the vacuum hose attaches. Just ease it off and check for gas.

#23 is the schrader valve - just like a bike tire valve - and #24 is the cap.

As I said before you can borrow one at Autozone or what ever parts store you go to.
 
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Again, I feel a little out of my league. I'm not sure my Burb has fuel injection. It has a carburetor and I don't see any injectors.

Here's the VIN: 3GNFK16R4XG183352.
 
VIN Decode 3GNFK16R4XG183352

3 - Built in Mexico
G - General Motors
N - Chevy
F - Gross Vehicle Weight Class - 7000-8000 And hydraulic brakes
K - Line and Chassis type - Conventional Cab 4 X 4
1 - 1/2 Ton
6 - Body type - Suburban
R - Engine Type
Engine Option - L31
Disp (L) - 5.7
Cylinders - V8
Fuel System - CPI = Central Port Injection
Made in U.S.

4 - Check Digit
X - 1999 Model Year
G - Plant - Silao, Mexico
183352 - Production Sequence Number


Notice your Fuel system = CPI or central port injection - also known as Spider Injection - see pic - http://www.amazon.com/ACDelco-217-3029-Fuel-Injector/dp/B000NW8EU8/ref=au_pf_ss_2?ie=UTF8&Make=Chevrolet%7C47&Model=C1500%20Suburban%7C425&Year=1997%7C1997&carId=002&n=15684181&s=automotive

Let me know if you see this type of system on your burb. Notice the brass colored metal part on the bottom of the plastic bowl - that's your fuel pressure regulator - look at the bottom of the FPR and see the metal tube coming out - that's where your vacuum line will attach. That's what you need to inspect for gas in the vacuum line.


Are you seeing a carb? Could you post a few pics of your engine setup? You shouldn't be seeing a carb? I wonder if your burb has had an engine swap?


After a little more research I think what you're seeing is the Throttle Body - which looks like a carb. Check out this link that shows your exact setup - click on the blue VIEW INFO button and you'll see the diagram - click the image to enlarge -
http://www.gmpartsgiant.com/Page_Product/PartDetail.aspx?Vin=3GNFK16R4XG183352&Make=Light%20Truck&Model=Models%2003,53,06,16,43%20-%20Carryover%20Model&Year=1999&MakeCode=L&ModelCode=K&CatalogCode=54C&RPO=UG1%20UP0%20UQ3%20VK3%20VP6%20VXS%20V22%20V54%20V73%20XBX%20X88%20YBX%20YD3%20YD6%20YE9%20ZBX%20ZM9%20ZQ3%20ZW9%20ZY1%201SC%201SZ%2013I%20132%2039U%206GH%207GH%20AG2%20AG9%20AJ1%20AS3%20AT5%20AU0%20AU3%20AXP%20A31%20A95%20BVE%20B35%20B39%20B58%20B71%20B85%20C36%20C49%20C6A%20C60%20C69%20DD0%20DF5%20DK6%20D55%20EVA%20FE9%20FF6%20FF7%20FG5%20F60%20GT4%20G80%20JB6%20KA1%20KG9%20KNP%20K34%20K47%20L31%20MSL%20M30%20NA1%20NF2%20NP5%20NP8%20NY1%20NZZ%20N33%20PF4%20QBX%20R6B%20R7V%20R9U%20SLM&eCode=L31&tCode=M30&mCode=CK10906&majorIndexID=03&PartSortBy=Key&minorIndexID=TX03-012&SortKey=97


From the bottom up you'll see the lower intake manifold which sits on top of the engine block in between the heads, on top of that is the central port injector, over that is the upper intake manifold, and sitting on the front of that is the throttle body, the air intake duct goes on top of that (not pictured).
 
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Yep, this is my configuration. I always assumed that the air intake (with the butterfly valve) was a carburetor. I just picked up a fuel pressure tester at Autozone and will check it tonight. Man, this has been really helpful.

If there is pressure and the relay is functioning is it assumed that the FPR is bad? From what I can tell, I'll have to remove the upper intake manifold to access it.

I'll report back tonight.

Thank you, again!

Eric
 
You never mention anywhere what the issue is with the engine. Why do you think you have a fuel related problem?
 
Okay - looks like I may have misidentified your injector type - instead of a CPI yours is a CSPI - Central Sequential Port Injection. "In a nutshell, the CPI system does not use a Mass Air Flow (MAF) Sensor and the Intake Manifold Plenum is aluminum metal and was used from 1992-1995 on the 4.3L V6 Engines only. The CSFI does use a MAF Sensor and the Plenum is plastic and was used from 1996 on up on the 4.3L, 5.0L and 5.7L Engines."

COMPLETELY READ THROUGH EACH TEST BEFORE YOU BEGIN SO YOU UNDERSTAND THE WHOLE PROCEDURE AND TOOLS YOU'LL NEED

The most common failure on these is a bad fuel pressure regulator - here a link to a test procedure for this possibility - http://troubleshootmyvehicle.com/gm/4.3L-5.0L-5.7L/testing-the-spider-fuel-injector-1

When you do the pressure test - with the fuel pump energized you should see a fuel pressure between 61-66 psi. If not then the CSFI system won't work.

There is another test that is labeled as a no-start test which I will give the link for as well but, I would do the leak test first as that indirectly checks the fuel pressure regulator and rules that out. Also, to do the first test you don't have to remove the upper intake manifold so it's a good first test.

Here's the no-start test link - http://troubleshootmyvehicle.com/gm/4.3L-5.0L-5.7L/spider-injector-troubleshooting-case-study-1 The probable cause here is something is clogged.

The great thing about having the CSFI system is that you don't have to replace the whole system if just one injector is broken.

When you're doing these tests I would have a bunch of extra rags to catch any escaping gas and if you have one a fire extinguisher. When doing the spray test on the injectors I wouldn't spray the injector into a rag - I would get a clear water bottle and spray it into that. If will capture the gas and you can see how well the nozzle spray looks.


Here's some interesting info - it's a conversion kit for the CSFI system for a new MPFI system with no mods or special tools - http://www.fuelinjector.citymaker.com/Vortec_spider_fuel_injection_conversion.html

Or on Amazon - http://www.amazon.com/gp/product/B000NW8EU8/ref=s9_simh_gw_p263_d0_i1?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-2&pf_rd_r=049548P0ABFKH88C5YFG&pf_rd_t=101&pf_rd_p=1688200382&pf_rd_i=507846

This is a lot of new info but it's really not that hard if you just take it step by step.

If you have any more questions just give us a post.
 
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Have you had a chance to read the replies efrice? Just wondering if you found them helpful and whether or not you feel up to doing the tests in the supplied links?
 
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