engine has trouble starting

Going to need more info, Is it a crank no start when failing, if so you are going to have to see what is missing,(spark, fuel, injector pulse), that will give you a direction to start diagnosing. this guide can help us fix it.

https://www.2carpros.com/articles/engine-cranks-excessively-before-starting

Please run down this guide and report back.

Same problem. Changed the crank sensor, harmonic balance, ignition modual, and a new fuel pump still no spark.

A week ago car began to start hard like. i shut it down wiggled some wires tapped on fuel rail and pressure regulator and it started. I let it run over an hour drove it couple miles ran great. so i shut it off and has not started sense. cranks over strong I tried security fix, then tried to start in neutral both to no avail. did not have fuel pressure gauge, but seemed like very little pressure out of release valve. so I replaced fuel pump and fuel filter. way more pressure, but still just cranks. I kept on charger while working on it. I am going to check spark today, I mean wires and coils look good, but we know that can be deceivin. I just do not understand ran for hour now no fire just crank. I have been researching everything about these cars. do not know what way to take could spark plugs go from running to fouled from cranking motor? Could it be pressure regulator causing no start ? crank sensors? Please help

scan for codes it can be anything electrical if you have correct fuel pressure . auto parts rent gauge and can scan for free. you can buy them pretty cheaply as well. See link for fuel pressure check should be 52-59 psi.
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Car cranks for a long time with no start. I turn the key off and crank some more and no start. I finally get a start on the third try. Next time I want to start the car I turn it on, then off, then on, then off, then on and then I try to crank it over and it starts right up. This tells me it is not getting enough fuel when it only gets one pulse to the injectors. It needs three pulses (key on, key off) to start. Does this mean the injectors are partially clogged? I should mention the car runs great once it starts. I have 50 psi at the fuel port (gauge attached) so fuel pressure is not a problem and it does not leak down. If it is the initial pulse not providing enough fuel, how do I fix this? Currently, I put Seafoam in a quarter tank of fuel. That has not made a difference yet. What do you think?

scan for codes and see if security light is on if it is reset security if it is a VIN 1 your pressure is low if it is a VIN K it is in range. VIN 1 should be 52-59 psi so it kind of sounds like it is a bad fuel pump.

Security light is not on. CEL is not on. There are no codes. I found on other sites that the normal range is between 40 PSI and 60 PSI, which indicates the fuel pump is okay. When I hook up the fuel pressure gauge and turn the key on the pressure is right there. It is not like the pressure takes time to build up. Bam, it is right there. The pressure regulator is good. The problem is the initial pulse being too little to start the car. As I said. I turn the key on and off three times and the car starts okay. Once started it has plenty of power. A bad fuel pump would not have the guts this car has. Thanks, but I believe the fuel pump is okay.

Hello,

Sometimes tests can fool you. Here is what I want you to do. Next time the engine will not start (on the first time) spray a little choke cleaner in the intake to see if it starts, this will determine fuel delivery or something else like ignition.

Please run this test and get back to us so we can continue helping you.

Cheers, Ken

I will try that tomorrow. I have read elsewhere that people have solved it by trying a different MAP sensor. Sounds unlikely but I am going to check the voltages on the MAP tomorrow. I also read that the engine temp sensor data affects the length of the initial injector pulse, which seems to be the problem........pulse too short.

Today I took off the MAF sensor and inserted a tube past the throttle butterfly and squirted gas in. I put the MAF back in and it fired right up. So, it is the lack of a fuel pulse or sufficient one on start up keeping it from starting. I did check the voltages on the MAP and they are normal........4.96v key on......1.12v at idle. I took the engine temp connector apart and ohmed it out. I got around 1000 ohms between the yellow and black wires. That seems about right as the engine was not quite warmed up yet. Besides, the dashboard temp indicator works. I can actually start it after just turning the key on twice.........I think the residual fumes from the gas I squirted in are causing this. Well, I still think the problem is due to the initial fuel pulse being insufficient to start it on the first try. What do you think?

Yep it makes sense that the multiple cycles of the key helps it. I think you should ohm out each of the injectors to see if one stands out, then disconnect that one and try to start it. Its like the injector drivers in the PCM are getting over loaded which explains the key cycles helping it.

I will try that tomorrow.

I had some time so I checked the injectors. They all read about 12ohms. I give up. I can live with turning the key a few times to get it started. I want to thank you and HMAC300 for responding.

The next thing it could be is the PCM itself.

Here is an update. I took the GP for a 60 mile ride and then the car started like it used to. I just touch the key and boom it starts. This lasted for a few days and now it's back to turn the key on, turn the key off three times to get it to start. I am now convinced it is either a bad ground or a flakey connection somewhere. I don't know where all the ground connections are. The starter works fine so I am assuming it is a small ground somewhere possibly related to the PCM. Does anyone know where all the ground points are?

most pcm's ground on engine so get the one on stud behind engine on trans and any other one on engine they will be easy to spot also get the one on battery to body it may go under battery and be corroded it will be a smaller wire.leading form negative cable.

Thanks. I will check those tomorrow.

My 99 Grand Prix GTP (3.8 Supercharged) is difficult to start. I have to keep cranking on it before it tries to fire and even then I have to be quick on the throttle to keep it running. When starting, I will turn on the key and listen for the fuel pump to stop running before I attempt to start it. My service engine light is not on, but I'm not sure if it may not be burnt out. It doesn't run super smooth after being started. I just don't even know where to begin looking for the problem.

Check engine light should illuminate when key is on, if not it is burnt out.

Take to autoparts store and have PCM scanned for codes, this is a good place to start.

I had the computer scanned for codes and my fuel pressure checked. Fuel pressure built to 50 psi and held. The codes that I got were:

P0650 Malfunction Indicator Light Control Circuit
P1374 3x Reference Circuit

I have been searching to find what these codes actually mean or some troubleshooting guidance.

The 3X reference signal is produced by the ignition control module (ICM). The ICM calculates the 3X reference signal by dividing the crankshaft position (CKP) sensor 18X pulses by 3. This calculation is performed while the engine is running, and while the CKP sync pulses are being received. The powertrain control module (PCM) uses the following information:

The 3X reference signal in order to calculate the engine RPM, and the CKP at engine speeds above 1,200 RPM
The pulses on the circuit in order to initiate injector pulses
A constant monitoring of the number of pulses on the 3X reference circuit
A comparison to the number of 3X reference pulses to the number of 18 X reference pulses and CAM signal pulses being received
If the PCM receives an incorrect number of pulses on the 3X reference circuit, DTC P1374 will set and the PCM will use the 18X reference signal circuit for fuel and ignition control. The engine will continue to start and run using the 18X reference and camshaft position (CMP) PCM input signals only.


This would have to be checked by GM or competent garage as P1xxx codes are manufacturer specific.

P0xxx codes are generic OBDII codes applicable to all OBDII PCM's.

The car stats right up after it has sat over night, but after it has been driven and gotten warmed up it is hard to start... I was leaning towards a crankshaft positioning sensor, camshaft positioning sensor, or coil pack control module..
Thank Dustin

first meke sure the fuel pressure is being maintained after the engine is off.

and how do i make sure it is maintaing preasure after its off and if its not whats the problem

you will need a fuel pressure test guage to do so, measure up the pressure with the key on turn the vehicle on run it check the pressure turn it off, then turn the key back on then off, watch the pressure, it shoudl drop less than 1psi per 2mins.

if it does it is either a bad fuel pressure regulator, leaky injectors or a bad tank check valve.

As I'm driving my car, my RPMs fluctuate while my foot is on the gas. This causes my car to bog down and then it picks up again. If my foot is NOT on the gas, my car will stall. In addition, sometimes when I try to start my car, warm or cold, it will not start. It will crank, but will not start. I'm thinking fuel pump, but what do I know. I have just replaced the computer, but this did not help. Could this be 2 separate problems or just one? I have a 3.4L GTP.

well you should probably install a fuel pressure gauge to be sure but it sounds like a weak fuel pump could be the problem. the fuel pressure should be about 38 psi

I have a 1992 Pontiac Grand Prix with a 3.1 Liter Engine and about 164,000 miles on it. I started the car one morning and it seemed to crank awhile before it finally started when it did start it seemed to be missing or running rich. It stalled on me a couple of times at a stoplight and now has a surging problem at idle. I checked the air filter and when I did I found raw fuel in the intake hose. The check engine light is not on so I am wondering what it could be any info or things I can check would be helpful. Thanks!

First thing I would find out the code and problem of the check engine light. That could be the root of problem. Which type of fuel injection do you have? TBI(Throttle Body Injector, 1 injection point) or MPF(Multi Port Fuel Injection, 1 Injector at each cylinder) Make sure the injectors are clean and installed securly/ correctly. I can't really think of hand what would put fuel in the intake hose except MAYBE a dead cylinder flooding BADLY. seems unlikely though. If you have the TBI then it may just be a dirty injector. If you have MPFI Then that's a bit tougher to figure out.

I have a 2000 Grand Prix GT 110,000 Miles. Lately it has been stubborn to start and often requires the gas peddle to be held to the floor to get it to start. When it finally starts it runs rich and spews gas rich exhaust fumes. It also will idle high (~2000 RPM) randomly. when I check the ECM the only error codes that I have gotten are P0125, which is insufficient coolant temp for closed loop operation. The local shop said they could find nothing wrong, but suspected that the fuel pressure regulator was to blame. I would appreciate any help that you guys could give me.

You could have a Coolant Temp Sensor that is out of range, or if the thermostat is stuck open it will set that code. Does it run cool? take a long time to get to operating temp? does it get to normal operating temp?

Actually I have replaced both the temp sensor and the thermostat in the past 4 months. the car does get up to normal operating temp and doesn't seem to take longer than normal. Every now and then it will run hot because it is idling at 2K-2.5K rpm. I should also mention that the service engine light also will turn off by its self after a while ( day or so, sometimes after only an hour or so). For the time the fuel system is my largest concern, being that the service engine light seems to be intermittent.

Thanks

Ther is a vacuum line that goes from th epressure reg to the intake manifold. Remove it and look for raw fuel, if it is present then the reg is blown and needs to be replaced. The only other way for raw fuel to enter the engine is if one or more of the injectors are leaking down.