My mom has a 96 regal with a series II L36. The car has been acting funny during start up. When the car is cold, like staring up in the moring after it has sat all night, the car starts fine. When the car is driven and it's started throughout the day, the car will sometimes not start when turning the key. When it does start, the engine will die unless the gas pedal is pressed to rev the engine a couple times. It's been doing it more and more lately.

I replaced the fuel filter but that did not do anything. It needed a new one anyway. The vacumm lines are good. I did notice a slight leak that sounds like its coming from the UIM. Would a warped or not perfectly bolted UIM cause something like this?

What other options should I consider looking at?

Also there are no engine codes.

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1999 GT|SLP CAI|Borla Catback| Shift kit|18" Koblenz|GMPP Lowering|GMPP handling|Blk Headlights|ER Rcokers|HV3|HV TB http://www.fquick.com/The_Guz

Check engine light on? Could be an intake leak, does it smell like or feel like its running hot. Thats usually what how most people describe it when a car is running lean. Also check the fuel pressure regulator, pull the vacuum hose from it and see if theres any gas on the vacuum side. A little gas is ok(very little, like smelling gas is ok but if its wet its bad) the diaphragm might be going bad. More info like a trouble code or somthing, it could be all kinds of stuff.

Could be a dirty throttle body as well.

I'll check this out. There is no engine lights so no code.



I'll look at this as well.


The car was running fine as the LIM gaskets were replaced two years ago with the new metal gaskets. It's also got a MAF that was replaced last year.

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1999 GT|SLP CAI|Borla Catback| Shift kit|18" Koblenz|GMPP Lowering|GMPP handling|Blk Headlights|ER Rcokers|HV3|HV TB http://www.fquick.com/The_Guz

Just because the is not on does not mean there isn't a pending code that takes multiple drive cycles to illuminate the light. Scan if you can.

Well I found a low mileage UIM at a local salvage yard. I suspected the original UIM was showing signs of it being warped. I removed the old one that has been on the car for 14 years and there was some oil in the UIM. Cleaned that out and installed the low mileage one. Cleaned the throttle body as well even though it was not very dirty. The car started right up with no hesitation. Took it on a test drive to get the car hot. Turned it off and it started right back u with no issues. I told my parents to drive it around for a few days to see if a warped UIM was causing this.

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1999 GT|SLP CAI|Borla Catback| Shift kit|18" Koblenz|GMPP Lowering|GMPP handling|Blk Headlights|ER Rcokers|HV3|HV TB http://www.fquick.com/The_Guz

Hmm... Mine has been doing this since I bought it, but it hasn't really bothered me. I might need to check into this a little more...

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x2

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2004 Grand Prix GT AGGRESSOR
PRJ PCM, Custom Exhaust, 180 stat, FWI Custom Intake, DIC upgrade.

Well it's been a few months and the car has begun with the same starting symptoms as before. I scanned the car for error codes and there was nothing reported back.

I have cleaned the IAC and that helped a little bit. But the car still has a hard time starting after it has been running. It starts up fine in the morning after sitting overnight. The MAF sensor is good so I know that is not the issue. I also have a replacement O2 sensor to replace on the car as part of a tune up. What are the odds of the PCM going bad? Could the crankshaft position sensor be the problem? Or possibly a weak fuel pump?

Again the mechanic I took it to, could not find any issues with the car. He specializes in GM cars and tested the cols, plugs, battery, battery cables, alternator and various other electrical connections.

Any other suggestions?

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1999 GT|SLP CAI|Borla Catback| Shift kit|18" Koblenz|GMPP Lowering|GMPP handling|Blk Headlights|ER Rcokers|HV3|HV TB http://www.fquick.com/The_Guz

I had a similar problem with the Grand Prix. It would start up fine when cold, but would never start up on the first try when hot, even if the car was sitting for several hours. I had already replaced the fuel pump, filter and relay before this problem showed up. Turned out to be a bad fuel pressure regulator.

Yeah, a crank sensor that takes some heat could be failing. It does seem awful coincidental though, that when you replace the UIM, the problem went away, and in time it came back. I'm not sure what to think on this. My first GUESS would be crank sensor, and then check fuel pressure, and see if a regulator is failing.

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One Big Ass Mistake America

So I ended up picking up a replacement fuel pressure regulator. The car has been starting with no issues fro the past couple of weeks. I told my folks to keep an eye out to see of the problem persists. But so far so good with the new regulator.

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1999 GT|SLP CAI|Borla Catback| Shift kit|18" Koblenz|GMPP Lowering|GMPP handling|Blk Headlights|ER Rcokers|HV3|HV TB http://www.fquick.com/The_Guz

^^Glad to hear you found the problem with it..in my case I suspected the regulator was probably bad, so I pulled off the vacuum line and sure enough, there was gas dripping out of it.

Sorry if I am in the middle of this topic and maybe a little off track. I have had and still have starting issues with my 2004 Pontiac Grand Prix GTP. It will start when it is cold 100% of the time. Some say that they have a bad fuel pump resistor, but my 2004 does not have the fuel pump resistor. I have looked all over and I am not sure which way to turn right now. I have changed the ignition switch, the starter, the fuel filter, heck even put in my spare PCM. Again the car will start 100% of the time when it has been sitting for an hour or more. If I shut the car off after I have driven it for a half hour or more and then try and start it within 15 minuets it normally will not start right away. I need to crank it quite a few times to get the engine running. When the motor is running it runs fine and you can drive it all day with no problems, until you shut it off. I have seen postings on the GM complaint site of the exact issue, but I am not sure what the resolution to the problem is.??

You're going to kick yourself when you find out that the solution costs about 3 bucks and you didn't need to replace all those parts. Your throttle body is dirty and just needs cleaning. What happens is the carbon/dirt/oil buildup on the throttle plate restricts airflow into the engine while starting, but the problem doesn't happen during cold starts because the throttle body opens slightly to allow more air in until closed loop operation. But that does not happen when the engine is warm, hence why the problem only happens when the engine is warm or recently running.

Here's a DIY:
do-it-yourself-f12/clean-your-maf-throttle-body-t3899.html

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Dubs:00 VW GTI VR6, Low and Slow; 91 VW GTI 8v, Restoration Project; 91 VW Cabriolet 8v, bitch Basket
GP's:04 GP GT, Past now G-Ma's; Ex-Girlfriend's 97 GP GT, "Project Pink Power"

Thanks Playboy, I will give the cleaning of the TB a try. If I use carb cleaner will that work ok also, or does it need to be specific TB cleaner ?

I've used carb cleaner before without any problems. Just be careful when cleaning and try not to actually push on the throttle plate with too much force cause it could mess up the electric servo in the TB.

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Dubs:00 VW GTI VR6, Low and Slow; 91 VW GTI 8v, Restoration Project; 91 VW Cabriolet 8v, bitch Basket
GP's:04 GP GT, Past now G-Ma's; Ex-Girlfriend's 97 GP GT, "Project Pink Power"

[b]
Planeboy18[/b]

Update,

I cleaned the Throttle Body, it did not fix the problem. The Throttle Body looked like the other pictures posted, black on the inside and also the inlet of the Supercharger. I cleaned things the best I could.
I did find a wire on the fuel pump that seemed to be bad, I repaired it. I am NOT sure if the bad wire is the problem or not?

I still feel it could still be something like the Cam Sensor. The issue with a Cam Sensor is that it acts up when it gets hot, maybe after it sets for a few being hot it brakes down, I REALLY HAVE NO IDEA AT THIS TIME WHAT IS WRONG. The Snap On Scanner did not pick up any codes or anything pending wrong. One day at a time I guess !

It sounds like the same issue I had with the regal. I got no codes and replaced the maf, cleaned the idle control valve and the upper intake plenum, a new starter, a new fuel filter and finally the fuel pressure regulator. The fpr was the thing causing the issue. Yours could be bad as well. My last step would have been to replace the cam position sensor. You might want to try one of those.

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1999 GT|SLP CAI|Borla Catback| Shift kit|18" Koblenz|GMPP Lowering|GMPP handling|Blk Headlights|ER Rcokers|HV3|HV TB http://www.fquick.com/The_Guz

Watch your tachometer and see if it jumps around while driving. Usually a bad cam sensor will give sporadic rpm reading on the dash. Also, when the engine is cold, do you get a "long start" condition where it cranks a while before it fires?

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Dubs:00 VW GTI VR6, Low and Slow; 91 VW GTI 8v, Restoration Project; 91 VW Cabriolet 8v, bitch Basket
GP's:04 GP GT, Past now G-Ma's; Ex-Girlfriend's 97 GP GT, "Project Pink Power"

First, the motor runs PERFECT when COLD. When I start the car and let it run to operating temperature for about 15 minutes tes and then shut it off for about 10 minutes its " then is when it acts up " Just to note the car does not have some of the effects of other mentioned problems like using the gas pedal to get it going, that does not work on this issue.

If the MAF was defective, I should be able to just unplug it and start it, I know the calibration of air flow would not be proper, but the motor should start and run. I have no problems related to MAF as far as the car running, gas mileage or anything else.

The car acts like it is out of time as sometimes it starts and acts just like the cam sensor is telling it to fire at the wrong time and it bucks and runs rough for a few short period of time. I know the Cam Sensor SHOULD show a code, but Should may mean most of the time.

The Mass Air is in this same category, it should show a code if it is bad, the Mass air would normally act up when idling, when the motor starts it runs perfect, I say WHEN it starts. If you let it set for about a half hour it will start ok and idle and run fine. There is NO lack of power or economy as I have checked that part several times.

Fuel pressure is 60 PSI so that part is fine. I have the carpet pulled back and the cover off the fuel pump access hole so I can hear the pump kick on, which it has each time.

One thing mentioned was the Fuel Pressure Regulator, where is it on the 04 Grand Prix GTP?? There is no fuel pressure regulator on the fuel rail like other 3800 motors, my fear it is in the fuel pump and that is not good. I replaced the fuel filter which is the return pressure line for the fuel pump as the 04 has one fuel line going to the fuel rail NOT TWO.

GUS, The issue you describe is like what I have seen posted for the Throttle Body needing to be cleaned, mine does not start by using the
gas pedal.

The pressure regulator on the 2004 Pontiac Grand Prix is in the tank. that is a gen III 3800 it has a return less fuel system so ther is not a regulator on the engine. That was the first year for that system.

NO CHECK ENGINE LIGHT ON AT ALL. SCANNER CHECKED WITH THE NEW SNAP ON SCANNER AND NO CODES OR PENDING CODES

For what it's worth, my girlfriends dads Buick LeSabre with the series 2 had a bad cam sensor and it never threw a code. It sometimes wouldn't start when warm, but during cold starts it would also take a long crank to fire, but most of the time it was completely fine. Also, it would just randomly shut off if you started to slow down sometimes. Replaced the sensor and it's been completely fine.

Basically what I'm trying to say is, it didn't throw a code, but still failed as confirmed by watching the rpm readings with a scanner.

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Dubs:00 VW GTI VR6, Low and Slow; 91 VW GTI 8v, Restoration Project; 91 VW Cabriolet 8v, bitch Basket
GP's:04 GP GT, Past now G-Ma's; Ex-Girlfriend's 97 GP GT, "Project Pink Power"

WHEN THE ENGINE IS COLD IT STARTS RIGHT UP NO ISSUE WITH LONG START AT ALL. I get a long start only when it is HOT, seems like the ignition switch stays in the start position at times when I try and star the motor when it is HOT after sitting after I ran it for awhile. NO Tachometer ISSUE AT ALL, it stays steady and accurate all the time. All Ignition switch and key is new.

At times I wonder if this is all worth the trouble or not? Soon I will have a new car as I have either checked or replaced all I can think of so far and the car STILL acts the same. Reworded the Ground cable to make sure that was not an issue. Replaced the Cam Sensor even though it was most-likely NOT the cause. I think the chances of the fuel pump causing the problem is a likely hood, but that is not an area that I would want to just jump into as they are NOT cheap. The car runs really good and just acts up after it has run for awhile when restarting is tried. Why would the fuel pump do it? Guess I am either running out of ideas or I HAVE run out of ideas.

Wish I could get rid of this BLACK background when typing, hard to see.

Oh well hope everyone is having a good weekend.

After doing about everything to my car, I may look into the Crank Sensor. I have changed ,,,,

Ignition Switch and theft module.

Starter

Cam Sensor

Fuel Pump

Cleaned TB and inlet on Supercharger

Checked and Cleaned PVC

After reading a lot about the CRANK SENSOR and some of the symptoms like POOR GAS MILEAGE, Not starting when HOT and so on it just may be worth it????
I was going to remove the Fuel Rail and check out the injectors and the flow through the fuel rail, but I may just look at the CRANK SENSOR first. Symptoms of not starting correctly when HOT is not an easy fix. This is NOT affected by the gas pedal as some of the other listings posted.