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I am having a nightmare with my 2003 Chevy Trailblazer. Here is the history of the current repair so I can get some advice from you FINE GENTS hopefully.
OK, so I had the fuel pump bust a sending line the other day which dumped all the gas out and noticed it in a parking lot where it finally ran outta gas just as I was about to turn it off (idling).
So I replaced the fuel pump with a new one from advanced auto (Aftermarket) and then when I started it there was a slight knocking sound coming from the vehicle. I traced the sound and it didnt really seem to be coming from motor but instead from the exhaust and there was no physical pounding vibration being put out from the knocking through the motor I could feel with my hand. Then I was getting a P0300 or random misfire…so I drove it for a few miles and it finally registered a P0306 or cylinder 6 misfire. So, I swapped the ignition coils and spark plug from cylinder 6 to cylinder 2 and drove a min and the misfire migrated to cylinder 2.
I replaced the ignition coil and spark plug on the now misfiring cylinder #2 and no more misfire! So, I figured it was just happenstance that had a ignition coil went at same time as the fuel pump.
Well…then I drove the car about 30 miles after this repair and noticed a reduction in power gradually and at same time the SES light came on now kicking out a P0172 code or SYSTEM TOO RICH (Bank 1).
Figuring the system was just catching up I reset the code and carried on, well got halfway home from family on christmas and lost almost all power on highway dropping down to about 20 mph on expressway and had to take back roads home rest of the way. Basically it didnt have enough power to maintain speed above 30mph and if u lightly touched the gas it would speed up, but if you went any more then lightly feathering the gas pedal it would bog down and loose speed.
I drove next day and seems like it is running better when cold and when it warms up it looses even more power and runs even worse.
Freeze Frame INFO Data:
Calc Load% 95.7%
ECT(c) 91
STFT B1% 0.0
LTFT B1% -11.7
MAP(kPa) 74
Eng RPM 1461
Veh Speed (km/h) 7
fuel sys CL
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Concerning Live Data Info02S B1 S1(V) .765
STFT B1 S1(%) -19.5
O2S B1 S2(V) .785
STFT B1 S2(%) 99.2 <------ (This Seems Wrong To ME) ??? Also running LTFT numbers are regularly showing anywere from -5 to -15 or so while under load while STFT are holding steady between +5 - -5 depending on loads while runing. but LTFT seems to always go into the -15 or so anytime load is put on...NEVER to POSITIVE numbers side. My concern is that all this is happening right after installing this new fuel pump...I dont wanna keep chasing down problems if the fuel pump has something wrong with it and seems odd that all this happens after I swaped out the fuel pump but not before...However, the vehicle did run outta gas at a stop and this might have had an effect on the systems. Please, any advice will be hugely appreciated and I WILL CHECK this forum regularly for any questions or updates any places here. Thanks. Brad!
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There seems to be a string of people having issues with aftermarket fuel pumps being bad from the store. I would say take it back and get the ac delco brand one or a good brand name one.
BTW the STFT is really high and what you are saying both point to it starving for fuel. Most I have ever seen a properly running car with was +- 25 for stft or ltft.
I would just check any connections you may have made/fixed real quick first and if they are all good id take the pump back and get an OEM Part from a good brand name.
would a problem with the fuel pump in there be detectable with a fuel pressure tester, testing at the fuel rail?
Should be able to hook one up and check it. I would check it at idle and rev it also just tape the gauge to the window (painters or masking tape) or have someone rev the car while you are looking at it. Just remember safety glasses and that you have it tight on there. Also make sure you are clear with your commands I have nearly had my hand amputated by older techs that can’t hear well.
Check the intake manifold gasket for air leaks and ensure the bolts that hold it on are snug/tight.
Fuel pressure testing the system wouldn’t hurt either.
[quote=”DormanPartFail” post=123066]Check the intake manifold gasket for air leaks and ensure the bolts that hold it on are snug/tight.
Fuel pressure testing the system wouldn’t hurt either.[/quote]
Are the Intake Manifolds known for coming loose? Also…none of these problems were occuring before the pump line busted and I replaced the fuel sending unit…just seems strange that all these problems are suddenly occuring at same time/just after I replaced the pump.
Also…I replaced just one of the spark plugs on the same cylinder that I replaced the ignition coil on…could this kinda problem be occuring because I put a new plug in one cylinder and didnt replace the others???
I wouldn’t worry about a leak from the intake manifold. If the intake did have some kind of a vacuum leak, the PCM would have set lean codes instead of rich codes. The rest of your plugs should be replaced at some point in the near future, but the other five plugs shouldn’t be causing any rich mix problems if they’re firing normally. If you’re not feeling another misfire or some other kind of rough running, I’d forget about the spark plugs relative to the rich code.
I’m with everybody else in that it’s just time to test fuel pressure. Look at and record pressure when cycling key on, engine off, and then again with engine running at idle and during throttle. When you cycle KOEO, the fuel pump should prime up for a couple seconds and then shut off. The fuel pressure should drop a few PSI once the pump shuts off. Record that rest pressure too. Come back when you’ve got some numbers to throw at us.
Good Luck.
Here are all the Scanner Graphs that I have taken…Please keep in mind I have only driven this about 10 minutes since manually resetting the computer and I have not driven it enough yet to get the P0172 code to kick off yet…I figure another 10 – 20 minutes of driving will get the code and a freeze frame to be generated….till then this is what I have.
Please offer any suggestions or thoughts you might have with this live data info added into the infomation now provided…
My concerns… Is the rear O2 Sensor bad causing the loss of power…or would it be more likely for a bad catalytic converter to be causing this, or could this possibly be an injector problem or something else??? Please, any input is helpful!!!
Thanks,
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Check fuel pressure regulator, could be leaking internally. I have tested some pressure regulator by removing the vacuum line at the regulator right after running vehicle and found fuel in the line. I have also just removed the vacuum line while engine running held finger over vacuum line and the regulator spit out fuel just be careful, fuel can ignite. one other thing I seen done is to temporally replace the vacuum line with clear line then you will see fuel being sucked into the vacuum line. if you find fuel then it is leaking inside the diaphram.
ok…so I checked the fuel pressure regulator and it is fine…I tested to check if it was stuck open and tested to ensure that it wasnt stuck closed. Any other suggestions for the Rich Condition?
Someone suggested it could be a leak in the exhaust manifold gasket or that area but from my understanding a leak on the exhaust side would cause a lean condition not a rich condition correct? Well more specifically it would register in the O2 sensors as a lean condition cause exhaust gas would be escaping b4 the sensor and it would cause the fuel trim to richen not lean out…if I am misunderstanding how this works please do correct me! Same with a leak on the intake manifold…it would cause a lean condition not a rich condition…however I checked and intake manifold bolts are snug so not finger loose.
Please advise!
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