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

[Dwayne]

[quote=”wysetech” post=111784]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.[/quote]

I have read about that issue you described…I also want to thanks you for the input on the fuel pressure rising in the tank, and that is probably why I got the strange fuel pressure issue

[Stephen Bowen]

I’m still interested as well. Ignition switch? Yes, that makes sense. (as I kick myself, because VW has the same issues with the model car I drive….and I’m waiting for ours to take a dump..)

We need an icon for “PopCorn” on the forum. Cause this has a lot of us in suspense like a good movie cliff hanger.

S-

[Dwayne]

Well, no word yet on the cavalier. The owner said the tech got to start work on it yesterday afternoon…

I will update y’all when I know something

[Dwayne]

Update. ..the data link is getting too much voltage
Accord to the tech

It should be around 2 something but it’s over 6

This controls the module…

Now this is the info I just got, and there still trying to figure out why…I’m assuming it’s voltage there talking about

So I feel like I was on the right track with an electrical issue…

Any input from y’all on this?

What is going to be techs next move on his finding of this issue?

[Stephen Bowen]

If the data link is running to high, it can throw things off just as bad as to low. The proof will be in when the tech figures out the cause–which can be any number of things they will have to track down. It’ll be a matter of back probing the circuit using the schematic down the garden path until they find the issue.

S-

[Dwayne]

[quote=”Tedybear315″ post=112058]If the data link is running to high, it can throw things off just as bad as to low. The proof will be in when the tech figures out the cause–which can be any number of things they will have to track down. It’ll be a matter of back probing the circuit using the schematic down the garden path until they find the issue.

S-[/quote]

thanks for the input Teadybear315.

troubleshooting electrical issues can be time consuming, BTDT!, however I would have thought that the professionals would have discovered the root cause by now….

[Dwayne]

Well, I have yet another update for y’all…

The Chevrolet tech or techs had the car for over a week, and only and made their diagnosis…

Aftermarket radio wired wrong, or not wired properly causing a short, which causes the engine to just quit running ( I didn’t buy it) and thus also causing the data link voltage issue, radio removed and the cat is bad ( I didn’t buy that either). ” We got It running, but only by removing the O2 sensor.”

They told my friend that it would cost $1200.00 to replace the cat. The tech or techs that was working on it said off record ” I have a friend who will do it for 1/4 the price” ( I know the friend he mentioned, and he has a really nice shop. I have seen it)….so without a radio, and O2 sensor, off my friend goes to the other shop to have the converter replaced, and call it a day.

The other shop, going by the diagnosis of the Chevrolet techs, installs a converter ect, ect.

They give my friend a call yesterday to come pick the car up, It was ready to go, so my friend and his wife drive 30 miles to get the car, BUT! when they get to within 2 blocks of the shop, they get a call from the tech with bad news….”the converter didn’t fix the issue, we were backing the car out of the bay, then It just QUIT!…” We think there was a miss diagnosis, and we’re not real happy about that, we think it’s the ICM,( which I thought could cause this issue, but wasn’t 100% sure) I will buy one, install it and hopefully it will solve the issue, if not I’ll keep it, and not charge for it, and we’ll work out something on the converter price” (sounds like they are working with my friend)…

So this ant over yet, once the issue is finally resolved, my friend and his wife are going back over to the Chevrolet dealership, to straighten out a few things…

I will update again, when I know something else.

sorry for the errors in my grammar, I’m a bit upset! that my friends can’t get the correct diagnosis for the issue they have with the Cavalier

[Stephen Bowen]

I can relate with the frustration.

Here’s the thing about the aftermarket radio. Believe it or not? Yes that can cause a lot of computer related issues. Todays cars are all interconnected. Our VW is the same way. It has a “K-Line” in use. Basically it’s kinda like a data connection for the anti theft. I can see where a shorted wire can create that data issue. BUT that is only one possible cause of that line failing.

I am heartened to read that the shops are talking with each other in order to resolve this without going overboard with prices. (at least not any worse then it is now). Do I buy all they are selling? NO. Radio I can see in some cars causing issues. That’s possibly a good call-possibly. The converter and o2 sensor? I’m kinda struggling with that one. I can only hope that everyone steps up to the plate and makes this right for your friends.

S-

[Dwayne]

[quote=”Tedybear315″ post=112498]I can relate with the frustration.

Here’s the thing about the aftermarket radio. Believe it or not? Yes that can cause a lot of computer related issues. Todays cars are all interconnected. Our VW is the same way. It has a “K-Line” in use. Basically it’s kinda like a data connection for the anti theft. I can see where a shorted wire can create that data issue. BUT that is only one possible cause of that line failing.

I am heartened to read that the shops are talking with each other in order to resolve this without going overboard with prices. (at least not any worse then it is now). Do I buy all they are selling? NO. Radio I can see in some cars causing issues. That’s possibly a good call-possibly. The converter and o2 sensor? I’m kinda struggling with that one. I can only hope that everyone steps up to the plate and makes this right for your friends.

S-[/quote]
tedybear315, my friends car radio has been in that Cavalier for quite some time, and the radio had plug and play connectors on it, so apparently the radio wasn’t causing the problem, because it still has the same issue it went in for. I get that it could possibly cause an issue with the pcm if shorted out somehow,but now the techs say that they can wire it up correctly, so I think that was a misdiagnosis, and if they know how to wire it correctly, why did they leave it out…

The converter, I’m no expert..but all the experiences I have had with a converter are, they either are bad, and engine will not run because of excessive back pressure, or the engine will run at idle, but once you start to drive it under load it will hardly move when accelerating, and the bad egg smell from the exhaust. I’m sure that there are other symptoms of a going bad, or bad converter that I’m unaware of, and would like to know, because I’m kinda old school, and are learning some of this stuff as I go along through life:)

I hope too, that all involved with my friends, and the car that there trying to get back on the road for ther daughter, resolve the issue and make things right for them…

[Dwayne]

Update…problem was the ICM cassette
Now engine doesn’t shut down without warning…been running perfect all weekend, they put 150 miles on it:)

[Stephen Bowen]

While I love to see a happy ending and a successful repair?

This one is kinda bitter sweet.

This will be one that gets ‘filed’ away in the listing of oddball issues and likely solutions should this one kick up for anyone else.

Thanks for keeping us up to date–

S-

[Dwayne]

[quote=”Tedybear315″ post=112778]While I love to see a happy ending and a successful repair?

This one is kinda bitter sweet.

This will be one that gets ‘filed’ away in the listing of oddball issues and likely solutions should this one kick up for anyone else.

Thanks for keeping us up to date–

S-[/quote]
tedybear315
I agree, bitter sweet it is…but I feel good that the issue was resolved, and hopefully this thread will help others
thanks for hanging there with me:)

[Dwayne]

Please mark this thread “Problem Solved”
thanks for all the input folks…I enjoyed the ride:)

[EricTheCarGuy]

Glad you got it solved, thanks for the update. A couple of things.

First, a sulfur smell from the exhaust does not mean a catalytic converter is going bad. That smell is sulfur. There is no sulfur in the catalytic converter, it’s found in some fuels. As that fuel burns the sulfur is released and you get the smell.

As for checking for a clogged catalytic converter, that’s actually quite simple.

It’s not always a catalytic converter either. It can be a muffler or double wall pipe that goes bad internally that can cause an exhaust restriction.

Once again I’m glad you got it sorted out. Thanks for the updates and for using the ETCG forum.

[Dwayne]

[quote=”EricTheCarGuy” post=112886]Glad you got it solved, thanks for the update. A couple of things.

First, a sulfur smell from the exhaust does not mean a catalytic converter is going bad. That smell is sulfur. There is no sulfur in the catalytic converter, it’s found in some fuels. As that fuel burns the sulfur is released and you get the smell.

As for checking for a clogged catalytic converter, that’s actually quite simple.

It’s not always a catalytic converter either. It can be a muffler or double wall pipe that goes bad internally that can cause an exhaust restriction.

Once again I’m glad you got it sorted out. Thanks for the updates and for using the ETCG forum.[/quote]
thanks Eric! and I watched the video,vary informative, and easy for the DIYers to do
thanks

[Author]

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