Rough Idle after new fuel pump.

[viper79]

On a cold start it runs rough until I give it gas. Did this before and after fuel pump replacement. Replaced the FP due to codes and light popping up. Started to day with a fast rough idle, gave it some gas and smoothed out. When I got home I shut it off and waited 30 seconds, turned to run, waited 5 seconds-heard the FP charge, turn to start. RPM went to 0 to 3k then to 600 then rested @ 1k. No rough idle. Waited 10 minutes. Repeated the process above. It stalled when it came from 3k RPM. Started again, smooth. Car on takeoff wants to "holdback" until it get hot. Then it seems to be "normal". Checked the oil, age says it need replaced, but looks good. No glitter, thank God. Friends tell me it's the plugs.

Fuel Filter replaced last week.
FP replaced yesterday.

You guys got any ideas? I can't get it to a reader today, but maybe tomorrow.

[MKMike]

It really could be one or more of a number of different things.
When a car is started cold, especially in colder weather, the fuel mixture is harder to ignite, so the mixture is intentionally richer.
Anything that affects the fuel mixture at this time is going to be a problem.

A faulty fuel pressure regulator or a bad idle air control valve , for example.
Then there's possibly a faulty throttle position sensor, a sticky throttle plate, a vacuum leak or sticking egr valve, one or more partially clogged injectors......
Checking for trouble codes can help pinpoint the cause and, with so many possibilities, it's never a bad idea to begin with a basic "tune up" to ensure that there is nothing simple, easily fixed and inexpensive causing the troubles.
A basic tune up is to install a new air filter, gap and replace the spark plugs, pcv valve and (as you've done already) replace the fuel filter.
Checking the fuel pressure can eliminate or pinpoint fuel pressure as a problem.
A fuel pressure gauge is relatively inexpensive and some parts stores even loan them out for free.
That should eliminate the fuel pressure as the culprit.
To check fuel pressures, here's what you do:

(There is a valve, covered by a plastic cap on the metal fuel rail that feeds the fuel injectors which you connect the gauge to
)
1.Turn OFF the ignition.
2.Turn OFF the air conditioning system.

Wrap a shop towel around the fuel pressure connection when connecting or disconnecting the gauge in order to reduce the risk of fire.
The towel will absorb any fuel leakage that occurs.

3.Thread the fitting on the pressure gauge hose onto the fuel pressure fitting.
4.Place the bleed hose of the fuel pressure gauge into an approved gasoline container .
5.Turn ON the ignition.
6.Bleed the air out of the fuel pressure gauge into an approved gasoline container.
7.Turn OFF the ignition for 10 seconds.
8.Turn ON the ignition.


Take the following 3 readings and write them down
A) Read fuel pressure Key On /engine OFF (KOEO) should be above 50
B)Key On /engine running (KOER ) mid to upper 40's is typical running fuel pressure
C)Key on/ engine running -- disconnect vacuum hose to fuel pressure regulator and then reconnect it
When you do this there should be approximately a 10 psi increase in fuel pressure until the vacuum hose is reconnected.
If pressure does not increase, you have a faulty FPR.
There should not be any gasoline in the FPR vacuum hose.

You also want to watch the fuel pressure with the Key off engine off and see if it rapidly drops or steadily drops.
It shouldn't do either.
If it does, this often causes hard starting due to there not being enough fuel/pressure in the fuel lines initially.
Causes are faulty fuel pump check valve or a leaky fuel pressure regulator.

Service manual lists normal fuel pressures as:
2001 - 2004 VIN 1 & K KOEO 53-59 psi
2001 - 2004 VIN 1 & K KOER 3-10 psi less than above

[viper79]

fuel pressure regulator = sucks like a harbor hooker, got good suction and no fuel spitting out.

idle air control valve = new, but on cold start the bonnie idles around 1500 - 1750ish. Also, I notice when at this point when put in drive I can get the car up to 20 and second gear w/o gassing it. Normal?

throttle position sensor = not new. Cleaned as well as the TB.

MAF = new.

Vac hoses replaced.

The only thing that sticks out to me that I have not "taken car of properly" is the plugs.

What do I use to clean the injectors with?

My wife just came in and told me you know have to step on the gas to start the car. Any thoughts?

Most of the sensors have been replaced.

[96 SSEi]

unplug MAF and see if issue changes

also, what codes were you getting?

[viper79]

Plugs have 60k on them. I will check the MAF this morning.

[viper79]

Did the MAF unplug. Started, but not a smooth idle....not a rough one either. Bunch of pepper if that makes any sense. Turned off and plugged the MAF. Smoother again. Seems I only have problems in the morning during cold starts. I live in the midwest and we have been getting really humid foggy mornings. Codes are next.

[MKMike]

Misfires when the weather is humid can be caused by spark plug wires that are arcing.
Have a look at night when it's dark and you may see a light show of sorts underhood as the wires arc to various things.
If it isn't apparent, then you can then mist the wires to simulate very humid conditions and see if there is arcing going on.

fuel pressure regulator = sucks like a harbor hooker, got good suction and no fuel spitting out.

Had me laughing with the colorful description of this one.
Seriously though, there are definite pressures that must be present for the car to run well.
If your fuel pressure falls outside these parameters, it won't run well even though it runs.

What do I use to clean the injectors with?

Not an inexpensive deal.
The cheapest option overall may be this one which some forum members have used http://www.witchhunter.com/
The downside is that you won't have the vehicle to use for a while.

The proper way to clean them on the vehicle is for the fuel pump to be disabled and a fuel injector cleaner kit is attached which then runs the vehicle on a fuel injector cleaner, instead of gasoline.
This can either be done by a trusted mechanic or you can purchase a fuel injector cleaning kit and the cleaning solution from someplace like Amazon (didn't see any on Rockauto).
The former is significantly less expensive, but may have the "it's not my car" factor which is why so many of us opt for the latter.
The second advantage of owning a kit is that you can repeat the cleaning for only the cost of another can of cleaner, if the injectors are seriously munged up.

Not sure which ones are truly the most effective.
There are in-tank additives but I can't believe they would be as effective as running the vehicle on a fuel injector cleaner.

My wife just came in and told me you know have to step on the gas to start the car. Any thoughts?

Sure, the fuel pressure is dropping while the vehicle sits.
You may have missed it in the fuel pressure test I listed earlier, where I said

You also want to watch the fuel pressure with the Key off engine off and see if it rapidly drops or steadily drops.It shouldn't do either. If it does, this often causes hard starting due to there not being enough fuel/pressure in the fuel lines initially.

Causes include a faulty fuel pump check valve, leaky fuel pressure regulator, as well as one or more leaking injectors.

[viper79]

At the time of topic birth, the FP was band new. $300 Airtec. I hear it, but need to test pressure. I need to check the fuel pressure regulator. Can this be replaced?

[96 SSEi]

yes, the regulator can be replaced if needed .have you checked for vacuum leaks? listen when engine running
and you may hear a hiss indicating a leak. you can do a propane test also.
engine running, put nozzle of propane on all the hose connections and listen for increased engine idle: if idle goes up with propane, you have leak there

this can be done with carb cleaner also but start with a cold engine so you don't go up in flames

[viper79]

I will check both of them. How do I induce carb cleaner? Where is the regulator at? Is it on the injectors, the brass looking thing wrapped around the plenum?

[MKMike]

At the time of topic birth, the FP was band new. $300 Airtec. I hear it, but need to test pressure. I need to check the fuel pressure regulator. Can this be replaced?

You will find the parts prices are far more reasonable at RockAuto plus forum members use a code found in the Vendors Forum to get additional 5% discount.
The fuel pressure regulator is shown here when you click on fuel injection pressure regulator: http://www.rockauto.com/catalog/raframe ... el%252FAir
On the vehicle, the fuel pressure regulator is found on the fuel rail, which is the metal tubing that the injectors also connect to.
The fuel rail also has a Schrader valve, located underneath a black plastic cap, where you can connect a fuel pressure gauge to check fuel pressures.

The vacuum hose that connects to the FPR should not have any gasoline smell, nor should the regulator.
A bad FPR can take more than a minute before you'll see gas spitting out after you pull off the vacuum hose.
Here is an example of that happening:https://www.youtube.com/watch?v=AKtR_yF7bi8

[viper79]

Fair enough. Honestly, this is cheap enough to fix with out checking, but im going to any way. Is there a "how to" on changing this out?

[MKMike]

I had forgotten that there was actually a recall on the fuel pressure regulators
You can see if your car ever has the fuel pressure regulator recall done by GM.
The intake manifold can explode when the original defective regulator fails.
You can enter your VIN on GM's website and see which recall or recalls have not been addressed on your car https://my.chevrolet.com/recalls
View the recall description here http://www-odi.nhtsa.dot.gov/owners/Sea ... ids=202603

I don't think there are any write-ups on replacing one but you can do a forum search.
There is also a techinfo section and there's a sticky at the top of this forum with the common problems you can expect.

[viper79]

https://www.youtube.com/watch?v=9r8jdluu98o

Found this. Check this out guys, please. Let me know if this is legit, because if this is...I'd rather just change this and be done. If this doesn't fix it, I now narrowed it down.

Thanks for the help!!!!!

[viper79]

https://www.youtube.com/watch?v=AKtR_yF7bi8

Yes...Start, Stall. This is it. my smoking gun. Mike, when I get some more wiggiams this friday, I'll swap this slut out for a new one.

[96 SSEi]

How do I induce carb cleaner?

you will spray it on a small area of intake manifold and see if the idle changes, then you carry on to the rest of manifold- you do a small area so you can pinpoint the leak. do the vacuum hoses and connections the same way...'...good to know for future diagnosis

[viper79]

How do I induce carb cleaner?

you will spray it on a small area of intake manifold and see if the idle changes, then you carry on to the rest of manifold- you do a small area so you can pinpoint the leak. do the vacuum hoses and connections the same way...'...good to know for future diagnosis

Like I said before, I am not a car guru. You guys might be laughing, but spray...where? I build computers and make them run, so I pic cars up pretty quick. If you can take a pic and point where to spray. If I understand the concept is to spray on the IM and the fumes will get sucked in, thus changing idle?

UPDATE: I replaced the fuel regulator...after I smelled da da daaaa gas.... I am still getting a rough start in the cold morning. After warm up, fires every time and no start stalls....to my knowledge. I'm thinking tune. Last tune was 87k, I have 144k now.

I would like some dummy picks on "how to" where to spray carb cleaner.... Laugh if you want...we were all rooks at some point.

[MKMike]

How do I induce carb cleaner?

you will spray it on a small area of intake manifold and see if the idle changes, then you carry on to the rest of manifold- you do a small area so you can pinpoint the leak. do the vacuum hoses and connections the same way...'...good to know for future diagnosis

Like I said before, I am not a car guru. You guys might be laughing, but spray...where? I build computers and make them run, so I pic cars up pretty quick. If you can take a pic and point where to spray. If I understand the concept is to spray on the IM and the fumes will get sucked in, thus changing idle?

UPDATE: I replaced the fuel regulator...after I smelled da da daaaa gas.... I am still getting a rough start in the cold morning. After warm up, fires every time and no start stalls....to my knowledge. I'm thinking tune. Last tune was 87k, I have 144k now.

I would like some dummy picks on "how to" where to spray carb cleaner.... Laugh if you want...we were all rooks at some point.

Glad to hear that one issue has been fixed.
It goes to show you that while problems can have a single cause, there can also be multiple components of what seems to be a single issue.

It is easy to overcomplicate things and hunt for issues that can instead be easily solved.
When you know the car is already in need of a basic tune-up (spark plugs, air filter, fuel filter, pcv valve), then don't waste a bunch of your time chasing down troubles.
Tune it up and see if the problem is solved.
If the spark plugs wires are old, it certainly wouldn't hurt to change them, too.

Because the car is older, you can also expect that the vacuum tubing and seals, such as the ones sealing the fuel injectors, may have deteriorated over time with the further help of engine heat and vibrations.
There may be a vacuum hose routing diagram under the hood, to help you know where to look.
Typical vacuum leak spots include any vacuum hose (they crack/split, often where you can't see or get disconnected accidentally), the o rings on the injectors where they plug in to the engine, sometimes the pcv valve gets gunked up and sticks (cheap to replace) or it gets replaced and someone forgets to replace 1 of the o rings it requires.
The gasket beneath the EGR or the metal tube for the EGR can split and be a vacuum leak.
Vacuum leaks can sometimes be difficult to pinpoint,
If you look on youtube, Eric The Car Guy and Scotty Kilmer are 2 mechanics who post many instructional videos on how to do things like cleaning the throttle body and checking for vacuum leaks.
https://www.youtube.com/watch?v=9CPqbaSgcok is one by Eric the Car Guy that should help you out.

Another common issue is the throttle body getting gunked up over time. This can result in the air passages for the IAC getting restricted or clogged , the IAC (idle air control valve) itself getting gummed up and not seating fully , the MAF (mass air flow sensor) becoming unable to properly sense the air flow and the throttle plate sticking.
There is a special MAF sensor cleaner that is used, since other cleaners can ruin the sensor, and the rest of the throttle body can be cleaner with something such as CRC Throttle Body and Air-Intake Cleaner.

[viper79]

http://engineguy.com/media/wysiwyg/sensors_3800.JPG

1, 2, 3, 4 (cleaned) and MAF are all new.

FP is new. Fuel Filter is new.

The ACS Certified mechanic that installed the FP will be at the house on Saturday. He has a very expensive computer reader...this could get the bitch running. I love my Silver Slut,....yes I do.

He will look under her skirt and we will tag team this girl like two sailors on a 1 day leave....

[viper79]

Had my mechanic stop by and we discovered that we did NOT need to replace the FP in the first place. It was......a sparking wire. So winner winner chicken dinner to Mike! Cylinder 1 misfires 447 times and cylinder 2 misfires 40 out of a 3 minute idle test. Moisture played a key on why it did not start.

He hooked up some light gun and showed me that the misfire with a light show.

new plugs and wires are going in after Christmas, or when Ohio sees that Florida weather again like last Monday....

ADDED: Could this be a PK3 issue. I did a count of 3 and it stalled.