Car will sometimes not start after warm.

Holding the pedal to the floor sounds like the mixture is too rich or it's flooded. Sort of like the ECU isn't getting the temperature signal or maybe it's staying in the open loop mode. I'm stumped too - just throwing out ideas. That "Trac Off" and tach thing is curious too. I haven't heard of any tach failure causes. The "Trac Off" failures are usually a wheel speed sensor which is off the BCM not the ECU. --- It seems like it might be a flaky ECU but I'm just guessing.

Have you checked the fuel pressure? Could be ECU as mentioned above or possibly dirty injectors or fuel pump. Testing the pressure would rule out fuel related issues

We've tested the fuel pressure and the regulator. Last night we cleaned the MAF sensor, and it was doing better- starting good, no problem. My ex husband's computer said it was a bad MAP sensor. So we replaced that and cleared the codes. It was doing good. I went to the gas station, to get a coffee- came out and it started doing the "no start" again. I drove over to work (across the street) shut it off, and restarted with no problem. It sounds like I am crazy, but I am wondering if there is some kind of "field" in the area of a gas station- because that's where it always seem to give me problems.

Track off light WILL come on for a bad throttle position sensor. It will also cause it to shift very hard and at high rpms (like you're giving it a lot of gas) any codes in the system? I have first hand seen a throttle position sensor turn on the track off light, check engine light, and make the car shift like it has a B&M shift kit in it.

John, I think the next option is gonna be the TPS... ugh, more money. That trac thing drives me crazy, it doesn't happen all the time though- actually I think it hasn't been happening as much lately.

Check engine light on? Does it shift hard? TPS is pretty inexpensive and quite simple to change. Also forgot to mention that when it was on, the car was using a ton of gas. MPG went from 23 to 15. If you are seeing none of these symptoms then don't throw money at it.

The check engine light isn't working- possibly burned out...lol When I put the code scanner on it, it will pull codes. I need to check again since the last time- to see what's popped up. The car has been getting better since then about starting. I haven't seen the Trac issue lately either.

do you have a fuel filter in the fuel line? if so.. replace it.

It did have a inline fuel filter that had been changed. As of 2/8/13, I traded the car in. Problem solved. I hated to see it go, but it was getting too old for me to keep putting money into. :(

i have a 03 malibu 3800 v6 u start it runs/idles till the temp gets to around 170 or so then stalls wait 10 to 15 mins it runs for like maybe 5 mins also check eng lts on and the service tract lt is on any one possibly know what it may be

Go get the codes scanned, AutoZone does it for free

I have 98 Camry with the same problem... If you pay close attention you will notice that when you make a short stop say 5 minutes that is when you have restart problems . As long as you hold idle for a few minutes with gas pedal everythings OK. I am almost certain a temp part is the problem. If my car sits 30 minutes or more never a problem. Any one witn addl thoughts. Please jump in.

When was your last tune up? Could be your plugs are worn and the gas that would normally not effect them are effecting then since they are worn.

New plugs and fuel filter installed recently. By the way have had this problen for about 2 years.

Pull the vacuum line off the fuel pressure regulator.

When your car starts fine cold, then fails to restart while warm, it is usually a coolant system problem. Either low coolant, or bad coolant level sensor.

Hello my name is Mike I have a 2004 Pontiac grand prix gt right now I'm trying to start it and it wont turn on I'm doing the ignition system reset on it right now but having no luck I've checked the fule pump and it works fine but still not picking up I don't understand what is going on with the car I've also checked all the fuses I'm stumped

What's your fuel pressure, are your injectors pulsing, do you have spark?

My Mazda MPV LX (2000) is doing the same thing. Starts most of the time, then after a few days or a week, after a short stop, it won't start. Alternator was changed 6 months ago. New battery after the first non- start, new Neutral Safety Switch, too. Still didn't help. Very frustrating. I appreciate the tips offered here, and will check them out for my vehicle, too.

I just worked on a 05 Pontiac Grand Prix. His car starts fine in the morning. He would drive into work and sure enough it won't start. First I replace the Cam sensor. Then we were still was having issues starting it once the car was warmed up. After further review. I found the Crank Sensors was not working when the car was hot. Yep that did the trick. Car starts when cold and hot now. I hope this will help someone else who may be experiencing the same problems.

That's where the spark comes in, no spark in any of the cylinders you are looking at either a crank sensor or icm which can be tested at AutoZone.

I have an older Buick LeSabre that is exhibiting some of the same symptoms descibed here. Starts in the Am, a bit rough, but it starts. When its hot, it acts flooded. You have to hold the accelerator to the floor and when it fires, you tromp it real fast and it finally fires and stumbles and then clears and runs ok until you turn it off. I have cleaned the mass air flow sensor, and am now going to test the Fuel Pressure Regulator then I also saw that the connections on the Crank Shaft position sensor can get corroded and cause symptoms of complete failure. So, perhaps we should all check all of the connector pins on all the sensors... ie: The mass air The Throttle Position Sensor The Crank Shaft Position Senor The Injector Connectors The Air Idle Sensor on the throttle body and let me also mention the connections on the ICM behind the glove box and the PROM blue chip as few people talk about that and if it goes the ICM looses its brains. Happy hunting

By the way, mine ended up being the starter. My ignition still occasionally gets hot, so they say I may have to eventually have that changed, too, but so far so good.

Hi I have a two thousand grand prix that i bought about six months ago. As soon as i bought it i noticed the MPG drop from twenty three to now fifteen and is steady there. Also just recently it has been starting in the mornings, but then not starting if I leave it and come back within about twenty minutes. I've also noticed it shifting hard. Do you guys know what it might be? And also I replaced the power steering pump and now about a month later its started making that noise again. It may be a new noise but it sounds just like the power steering pump. Any ideas about any of these?

Oh and the rpms bounce up and down when idling, and bounce even more when I am accelerating and then let off the gas.

I had similar problems and symptoms with my 1993 buick Lesabre, It will start in the am and not after getting hot unless I floor it and tromp it fast. Then it stutters and barely starts and runs ok. Here is the answer: It was a gas tank leak at the seam! Imagine that! Why would that cause such a problem? The answer is modern fuel injected systems have a certain amount of pressure built up in the tank and in the overall fuel rails. So, even though the fuel pump is pumping, it is not pumping hard enough to get up to pressure it needs to start easily. Once running there is more vac from the engine and fuel pressures regular suction and its enough to run....but not really enough during start up.

I did clean up all the senor connectors, but in the end mine was the gas tank leak which lead to loss of pressure. Seal All worked to fix a pin hole leak in the seam of the tank temporarily. $5.15

Which of the problems did you're car have as well? Im hoping this could knock off a few of my cars problems

It was starting good in the morning and then hardly starting at all when hot. When it did finally start it would sputter and spit and you had to either floor it until it hit, and then really tromp it fast to get it past the stumbling.... It sounded like a timing belt was gone it was so bad......but, after it was all said and done it was a leak in the seam of the gas tank. Seal All, a $5.00 product fixed it for a day or so, and it started right up perfect. Then it stumbled again, so, I am sure I did not get it sealed up good enough on the seam.

Does anyone know if Roof Tar would seal up a gas tank? That stuff is thick and rubberized and may work? But, it may not due to its chemical makeup being that of petroleum.

I had a similar problem, would intermittently not start when warm. it stalled once at a stop light and would only start after cycling the key several times and 1/4 throttle. I tested the fuel pressure, all was normal. I replaced the temp sensor, fuel filter, fuel pump, spark plugs etc. The problem turned out to be a crank position sensor. I didnt want to believe it. I replaced it and the problem is gone. I hope this post help someone out. I wish I knew this $300 ago...

Oh, I forgot to mention that a classic sign that the crank sensor is faulty is an erratic Tachometer reading. The crank sensor drives the tach.

4 gauge wire from the negative terminal on the battery to your transmission mount will solve the problem.

My name is steve i have a 2000 grand prix gtp 188K miles on it. My car starts and runs fine when cold but when warm idles weird and when you shut the car off and go to restart it stalls out. Ive replace MAF, IAC, cleaned throttle body, replace crank position sensor and everything and the only code it has is o2 sensor

Replace the cam sensor that is located behide the main crank pully. That's what fix my problem.

Cam sensor isn't behind the harmonic balancer pulley, your referring to the crank sensor.

After reading most of the post above it seemed like my problem was the crank sensor or trottle position sensor. WRONG. When I first checked my fuel pressure regulator I saw no fuel when unplugging the vacuum line. So I double checked it by doing this, while running I unplugged it and plugged it back about 4 or 5 times. The last time fuel squirted out of the sensor. It must have been a small rip in the diaphram causing the problem I thought?! But that was one problem of 2! My other problem was the Coolant Level Sensor in the radiator! It was bad causing the Track Off light to come one and also the hard to start after warm up problem. After replacing the fuel pressure regulator and the coolant level sensor (Not the Coolant Temp Sensor! NOT) and clearing the codes in the ECM (computer) all is A OK now. Boy that sure was a hard one to figure out even with a code scan tool! Thanks for the information on this forum! 1998 Grand Prix 3.1 V6 was my car.

I have a. Grand prix 1998 it cranks up find but when i hit th gas it wont move. Can any one give me a clue y

Hello Niki, It sounds like a fuel pressure issue like I was having. If you do some searching on Youtube on there are a lot of videos out there about the fuel pressure issue on fuel injected vehicles. There is a valve, almost like a tire style up toward the firewall side of the vehicle and on top near the injectors. It is possible to attach a free rented gauge from AutoZone to test it.. Now comes the hard part. How do you improve the pressure if it is too low? The typical options are: A) Fuel Pump Replacement B)Fuel Regulator Replacement C) Clogged Injector cleanouts. Last but not least, like mine if you have a physical hole in the gas tank or along the seam of the tank, it can cause the pressurized tank to not build up enough pressure to run the modern day fuel injected systems. So, you either go to AutoZone and buy the fuel tank glue for a temp fix or a junk yard and get a used tank or pay through the nose for a new one. If I had it to do all over I would get a mechanic to do the pressure testing sooner rather than later. They have ways of pumping air into the gas tank and adding dye so that if there is a leak the red dye comes out in a visible gas form. If budget will not allow you to hire a mechanic, then find a friend who is willing to change the gas tank, fuel pump, and possibly the fuel pressure regulator on the fuel rail. The videos on line will help you with each potential job.

I have a 1979 Pontiac Grand Prix SJ as long as I'm giving it gas it runs but as soon as I let off the gas it dies and it runs rough I've changed the plugs plug wires thinking it could be that but that didn't help do you have any suggestions

I would buy some mass air flow sensor spray and use that on the small wire that is the sensor. It used to be that carburetors controlled fuel mixture ratios, now its all done by computers and they get their information from the mass air flow sensor. There is also a throttle position sensor and it needs cleaning every now and then or replacement. Those two would be my first suspects. If you do a search on You-tube for those two topics you will get enough clues to clean yours. Just do not use regular carb cleaner as it can wreck the mass air flow sensor. They make a very specific spray you can buy at Autozone or some other parts store called Mass Air Flow Sensor Spray. Never leave home without some of it in your trunk as your modern day cars can act up any time and you might save being towed if you just have the cleaner handy. Removing it can be a pain at times. It is a black square 1.5 inch by 1.5 inch chip on the throttle body on most gm cars. It has 4 small phillips screws that hold it in place. You unplug it first then push down on the screwdriver really hard while you try to turn the screws out to avoid striping them out. The heat sort of welds them in at times and they can be hard to get out. So, be careful and be patient. Use the right size of phillips head to give you the best grip.

Hello I have a 2000 pontiac grand prix I've been having a problem with it for a while now it will crank over but will die shortly after if I keep the rpms over 3000 it will stay running as soon as it drops under that it will die I have replaced the fuel pump, spark plugs, crank shaft sensor, and the harmonic balancer. Still having the problem after that I thought about the ignition lock cylinder and still no improvement I'm running out of ideas as to why this problem keeps occurring any idea what it could be?

My Sebring 06 convertible with 6 cylinders has had the same problem for about a year now. I took the car to three different mechanics including the Chrysler dealer. The dealer and a second mechanic each kept the car a week at a time and drove it but no one could figure it out. The car starts right up when it is cold. It starts fine after it sits and cools about half an hour after it is being driven for at least 20 miles or half hour. However about 10 to 20 minutes after shutting it off it sometimes has a hard time restarting and running. It does not do this consistently, but when it does it keeps stalling. I can usually get it going by flooring the gas pedal, and if I can get it going, it runs okay after a rough start. Sometimes I can't get it going, and I have to wait around 30 or so minutes to get going again. It feels like it is not getting gas. This only happens restarting the car after a short break (10-20 minutes) after the car is being driven at least 30 40 minutes or on the highway for at least 20 miles. In the last six months, I got a new battery, new alternator, a new hose for a leaky coolent. After I replaced the alternator, it didn't do it for about three months. Recently it started happening more and more often. The engine light came on again today. It's always the same... PO 300 multiple cylinder misfire... Mechanics say that this does not give them much information. It never did it under the watch of a mechanic.. I would appreciate any insight or ideas... Nadine

I'm having the same problem with my 2005 Sebring Convertible. Wait exactly 30 minutes, and it will start and run fine. Almost acts like some theft deterrent circuit timing out, after a false problem detection. Sebring uses a key with a chip in it.

It only does this when I drive more than 10 miles. It starts but stalls and does not go. Sometimes check engine comes up and it is always the same, "multiple engine misfire" I've taken it to a mechanic again. They out new spark plugs but it wasn't fixed. The horn also started going off at random times sounding like an alarm. They had to disconnect it and add another horn on the dashboard. Never another Chrysler again! This will be my last! Since then the

1998 E150 V6 hard start when warm, I replaced DPFE sensor replaced plugs, coil wires and today the gas pressure regulator that seems to have fixed it, old regulator didn't have a gas smell must of been sticking

Trey I have a 2004 Grand Prix and today my girlfriend was driving to pick me up at work and she said she was coming down the road then all of sudden the car started revving up and wouldn't go no where.the transmission has not been acting up none nor slipping. The car has had idling problems when you go to start the car and the forums that I have been reading have been talking about crankshaft sensors problems and fuel problems.Also when tried to restart the car when I got. To it, it would not start. Any suggestions would be greatly appreciated. Thanks for any help.

For the Pontiac Grand Prix: If the tachometer reads 0 RPM while the engine is cranking or running, there is a fault in the crankshaft position circuit that includes the sensor, wire harness, ignition control module, and engine control module. A defective sensor won't transmit the correct reluctor wheel signals back to the ICM and ECM causing improper or no spark leading to engine stalling or misfires. However, a defective ICM could cause erratic power/ground (voltage) to the sensor leading to inconsistent crank readings. Intermittent spark issues are difficult to troubleshoot. If you're just part swapping, replace the ICM first, then the CPS, and finally the wire harness.

check your crank position sensor may be the cuiprit

Make sure your coil pack is tight and making good ground with motor.

If idle is high, and or transmission won't shift, look for bad vacuum lines, or disconnected vacuum lines. They cause more problems than you can imagine. They keep falling off my '99 Pontiac Gran Prix. Also prevents start up, at times.

Car won't start after tach goes to 0 rpm's while running. Takes seconds to minute for it to stall, then will not stay started. Can take up to 2 hours before it will run again for more than a few seconds. Is definately the crank position sensor. Backfires badly due to raw gasoline in the catalytic converter, due to loss of spark in cylinders.

I bought a used Toyota, standard transmission, and before I brought it home it stalled. This was my fault because it had been 20 years since I had driven a standard shift auto. I tried to re-start, and I got nothing. No engage, no turnover. Within a few minutes, I got it started. For the next few days I noticed that the same thing happened intermittently. I looked online for help. Somewhere, I learned that there is a sensor on the clutch that does not allow the engine to turn over without the clutch fully engaged. Then I realized I had, on occasion, not been fully depressing the clutch when starting the car. Since then, I consciously depress the clutch fully when starting. No problem since.

HELP HELP HELP HELP...IM GOING INSANE...I have a 03 grand prix gt 4 door it cranks but will not start. It shut off a couple times n after set it started but now wont start 4 anything...changed fuel pump, plugs, crank sensor, checked all relays, fuses, n sensors ,n nothing...no check engine light, was on 4 a 0141 & 0139 code but not anymore...track off light is on, been on since bought, & it has started not letn key go 2 release without some time n effort but eventually will come out...I'm lost n ready 2 scream