Strange things happening with fuel pressure…

[Dwayne]

I’m currently working on a car for a customer, that has strange things happening with fuel pressure…

Vehicle is a 2004 Chevrolet Cavalier with Ecotec 2.2 automatic 117,000 ish miles

I have repaired numerous issues with this car over the last few monthe, and now there is another issue that need to be resolved. I’m no professional auto tech, but I Lovetowrenchit!, So here we go…

Complaint
1. engine will run rough at idle sometimes, engine will run smooth sometimes, engine will be hard to start sometimes, engine will quit running sometimes, engine will shut off sometimes when cornering, leaning ect.

2. CEL comes on sometimes.

3. I take a chance on driving the car, never know when it will quit running, and if it does…It will be hard to restart, but it can be restarted, and will run

What I have done after work hours, and what my finding are. I’m suspecting a fuel issue of some sort

1. Pulled trouble stored trouble code, cam back P0300..YUCK!! I know I’m in for a real fun time with this one Lol

2. Hooked up my fuel pressure tester, tested fuel pump for pressure KOEO got 60psi, Okay, good!

3. I decided to see if she will have a problem starting and running, fired right up, and ran smooth and without any misfire…Good:) while running fuel pressure dropped down to 57psi Good!…

4. After about 20 minute of no evidence of the initial complaint. I shut the engine down, and watched the fuel pressure needle. It dropped from 57psi down into low 50’s, but over a period of time, about 1 hour the pressure was down to low 40’S, after several more hours, pressure down to the 30″s, let the car sit over night, got up to go to work the next morning, checked the pressure gauge…it was ” 0 ” psi.

This is where it gets weird. I went to work that day, came home 12 hours later, looked at the fuel pressure gauge, and somehow the pressure went back up to the 30 ish psi range. Well i didn’t expect that Lol..now I’m scratching my head trying to figure out what is going on…

5. I decided to do a fuel pump volume test KOEO and got around 1 Qt in about 40sec..Good!
don’t think the fuel volume is a problem…maybe the fuel pump check ball is leaking, slowly…still a possibility

6. I got to thinking maybe a vacuum leak, fuel pump pressure regulator issue, leaking injector, or injectors. Well before I could start figuring out which way to go with my troubleshooting, I smelled fuel. I spotted some fuel on the outside of the fuel pressure regulator where it is mated together, and thought how could that be happening??

Well, I don’t have any fuel in the vacuum line, and the vacuum line is hooked to the intake boot, and not on the manifold, so no vacuum at idle on that hose. I’m not sure if if it has any vacuum at all on that hose. I pulled that line off the fuel pressure regulator while engine was running, for about 10 minutes or so, and no fuel pushed out of the regulator.

7. I’m going to purchase a new fuel pump regulator tomorrow, not sure if it is causing the pressure bleed off, because when I pinch the return hose I get pressure increase of 10 psi or so, that seems normal to me from what I know.

I am purchasing the regulator tomorrow to take away a fire hazard, and hoping that the diagram inside has a small rupture, and all this troubleshooting will end, without me going to troubleshoot the fuel pump…

I would appreciate any help/direction on which way to go. I don’t want to drop the tank unless I need to, and want to keep the cost as low as possible, for my buddy

thanks for taking the time to read this, I appreciate it:)

Topic

[EricTheCarGuy]

Let us know if things change after installing the fuel filter, or if you’re able to get a reflash.

[Dwayne]

[quote=”EricTheCarGuy” post=110748]Let us know if things change after installing the fuel filter, or if you’re able to get a reflash.[/quote]
We’ll do…I got the new WIX fuel filter for the owner, and plan on installing it in the morning, then I will run my test…and report back with results, good or bad
thanks!

[Dwayne]

[quote=”barneyb” post=110519]Hard to say if free or not. The thing is with the VIN you could at least find out what reflashes are available if any, what they are supposed to correct and if any have been done to the vehicle.[/quote]
Barneyb, we’re working on getting that vin number ran through the GM Technical System, what ever that is…and I’ll let you know what I find out, if anything

[Dwayne]

Okay, I changed the fuel filter today, was going to do it yesterday, but wife issues comes first:) Always:)

Here is the outcome…same symptoms, however the old filter needed changed out. The old filter was dirty, and blackish gas poured out of it.

I thought the GM oil pressure switch was part of the fuel circuit on this car( like it is on most GM vehicles, so I have read) and possibly causing the engine to just shut down because of it being defective(since the pump relay only operates at start up)that was not the case.

I looked at the wiring diagram in the manual I have, and it showed only one Tan/Blk wire for the oil pressure sensor, thus blowing one of my possible causes of this issue

I guess once the pump relay drops out, the PCM takes over supplying the voltage to the pump? my book is vague in lots of troubleshooting areas.

Well,today I have done the Power Balance test, and all cylinders have the same drop in RPMS.

I put the fuel pressure gauge back on the Cavalier, and get 50psi on initial KOEO, and get 48psi while engine is running at idle. When the engine dies, the fuel pressure only drops a few psi, and when I manually cut the ignition off I get 44psi for for a short while like 20 minutes or so. The fuel pressure acts more normally now, but I’m still not ruling out the fuel pump at this point.

Now the other part that I thought was causing this issue was the fuel pump relay, however I think I have ruled that out, by taking the cover off and watching the contacts when Initial KOEO, and when the engine just quits.

I have checked all the grounds per the electrical schematics, and all are clean, tight, and in correct places.

I’m now trying to figure out which direction to go with my troubleshooting…I feel like it’s an electrical issue, and possibly the ICM which is part of the CSI system, however my manual doesn’t give basic testing on this system, or my OTC book is crap.

I do have a cheap code reader with limited LD and will post my PIDs , and maybe someone who is better trained reading these could point me in a direction I need to go, and again thanks for all the help in resolving this issue. I don’t give up easily, and may be getting close to my limit when it comes to troubleshooting this issue.

LD Pids at Idle

Fuel System 2 N/A
Calc Load (%) 22.4
ECT (*C) 84-85
STFT B1 (%) 5.5-7.0
LTFT B1 (%) 0.0
Map (Kpa) 32
Engine RPM 612-625
Veh Speed 0
Spark Advanced (*) 7.0-10.5
IAT (*C) 46
TPS (%) 10.6

O2s Loc B1S1_ _ B2s_ _

O2s B1 S1 (V) 0.85-0.840
STFT B1 S1 (%) 6.3-8.6

O2s B1 S2 (V) 0.085- 0.720
STFT B1 s2 (%) 99.2

thanks for any help interpreting these numbers. I do understand some things but not all

[Dwayne]

http://youtu.be/4cTr7hgyYoU
here is a short video of the stalling issue after start up
this is 1 of 2 videos I will post

video 2. the engine was stable enough to let me raise the RPMs a bit, then back to idle, and it quit
http://youtu.be/2sTf_gDmD68

[Dwayne]

Where did everyone go..Lol…has anyone had a chance to watch the two videos I posted…

I have found something of interest, and will post it tonight, after work

[Stephen Bowen]

LOL.

We’re still here. During the week I’m at work. I try to sneak on here using the laptop. Let us know the interesting part! I’ll bring out the popcorn for the ‘movies’

S-

[EricTheCarGuy]

Based on what you’ve posted there I would say that fuel pressure is not the issue. I believe it’s time to turn your attention to the ignition system. Have you replaced any parts there recently? I also noticed a bunch of wires that looked like they would belong in a harness on the back side of the engine. Have these wires been tampered with in some way?

[Dwayne]

[quote=”EricTheCarGuy” post=111686]Based on what you’ve posted there I would say that fuel pressure is not the issue. I believe it’s time to turn your attention to the ignition system. Have you replaced any parts there recently? I also noticed a bunch of wires that looked like they would belong in a harness on the back side of the engine. Have these wires been tampered with in some way?[/quote]

Thanks for the input Eric…I too think it’s an electrical issue.
This car was purchase at a used car lot, and yes someone was into most of the wiring at some point. I have noticed old electrical tape over wires, also some new wire looms,skinned wires for probing, which was all covered up.

I have done major work to this car in the past, but never bothered the wiring harness, except for unplugging electrical connectors. This issue just popped up a few months after I completed the work, and after sever thousand miles were put on the engine.

I don’t have the car here at my home to work on at the moment, and will explain where it is in a separate post

thanks again

[Dwayne]

for all who have been interested in this thread, I thought y’all would like to know where I’m at with the issue.

The owner, who is a vary close friend decided to come pick up the car and take it to a Chevrolet dealership to have it a professional tech try and pinpoint what is causing the issue. I thought it was a good idea at this point since I’m not a professional tech, just a ” Shade Tree Tech “. I hope that whoever works on it, graduated from ScannerDanners class with top honors!!

I feel like I have failed, because I had the car for a few weeks, and could only work on it a limited time after work, and weekends. I ran some test, and replaced a leaking fpr, and installed a new fuel filter, but couldn’t pinpoint what was causing the stalling, because of limited time. I felt like I was in the right track with it being an electrical issue, but it would have taken me a bit longer, and more troubleshooting procedures on the CSI system.

My friend is in no way upset at me or nothing,he and his wife are cool folks, but they need to know what exactly is causing the issue, instead of throwing parts at it…and I agree

I will post what is going on, or what the tech thinks is going on with the enging, ASAP.

I would like to know too, and are awaiting for the diagnosis

[Stephen Bowen]

There is no shame in having to see the project go to a dealership. They have some special tools and test thingies that hopefully will allow the issue to be found.

Please keep us informed as to what the final resolution is. Most of us have our PopCorn at the ready and have been following this with great interest.

Don’t feel bad at all!! This has stumped the bulk of us as well.

Plus everything you have done? Was NEEDED repair, and not throwing unwarranted parts.

Sometimes you just gotta keep the faith!

(That’s my RAH RAH speech. Any good?)

Just kidding. Actually we’ve all been there at some point in time. I’ve had issues stump the batcrap out of me on some of the complex games I work on. And it pains me to say “I can’t do this, Can we send it back to the field support center and have the bench techs look it over?”

So while it might hurt the pride? It’s the right call.

Just let us know what they find out!!

S-

[Dwayne]

[quote=”Tedybear315″ post=111708]There is no shame in having to see the project go to a dealership. They have some special tools and test thingies that hopefully will allow the issue to be found.

Please keep us informed as to what the final resolution is. Most of us have our PopCorn at the ready and have been following this with great interest.

Don’t feel bad at all!! This has stumped the bulk of us as well.

Plus everything you have done? Was NEEDED repair, and not throwing unwarranted parts.

Sometimes you just gotta keep the faith!

(That’s my RAH RAH speech. Any good?)

Just kidding. Actually we’ve all been there at some point in time. I’ve had issues stump the batcrap out of me on some of the complex games I work on. And it pains me to say “I can’t do this, Can we send it back to the field support center and have the bench techs look it over?”

So while it might hurt the pride? It’s the right call.

Just let us know what they find out!!

S-[/quote]
Thanks for the ” RAH RAH ” speach, and yes it was good:) and made me feel better already 🙂
So, for now it’s back to building my boat engine, which I have neglected to work on over the weeks…it’s calling my name Lol..

With the cavalier, watch it turn out to be the battery…I have a load tester but didn’t think about using it…
When I know what the tech think the problem is, I’ll post it so we’ll all know and could help others in this form

Thanks again Tedybear315

[Bill]

I didn’t read carefully through all of the help replies (seems like I missed or ignored this post) but did anyone ever consider that it might be the infamous G.M. ignition switch issue? Everyone’s brain is locked on fuel pressure even though fuel pumps on those cars were a pile of turds. From the videos I watched it looked like the ignition was turned off when it quit. Fuel pressure was perfect.

I don’t know of any vehicle that will hold fuel pressure forever after shut down. The heat of the day could make the fuel pressure rise by itself also.

Guess we will have to wait and see what the dealer Gods come up with.

Just some random thoughts :unsure:

[Dwayne]

[quote=”wysetech” post=111781]I didn’t read carefully through all of the help replies (seems like I missed or ignored this post) but did anyone ever consider that it might be the infamous G.M. ignition switch issue?

I don’t know of any vehicle that will hold fuel pressure forever after shut down. The heat of the day could make the fuel pressure rise by itself also.

Just some random thoughts :unsure:[/quote]
thanks you for your input, I appreciate it… GOOD CALL!

The Cavalier is an 04, and there was no recall for the ignition switch, however the owner mentioned to me that it maybe an ignition switch issue, because of the GM ignition switch problems.

I know that I was going to test that switch at some point, but to me it seemed like the ICM was just shutting the engine off…we’ll know at some point what the techs find

[Bill]

Yeah…..G.M. had issues with older cars as well. The switch smoked sometimes so they recalled them and installed a relay for the starter solenoid on the radiator support.

[Author]

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