98 Malibu hard start when cold

[Newbu]

Hi, when I start my Malibu (105,000 km) I've had for 2 years it cranks for a few seconds before catching and it will momentarily sputter but then run fine with no hesitations or surging after that while driving.

If it has been running and has only been shut off for about 5 min. it will start up right away but sitting much longer than that and it will crank and sputter again.

I have changed the fuel filter and idle air control valve to no avail and I was going to put a fuel pressure regulator in but did not notice a fuel smell when the vacuum line was pulled off so I didn't install it (when the engine was cold mind you).

It doesn't make much difference if I hold the key in the on position for a couple seconds before cranking. At times though when it does start after cranking, it races for a second like it has gotten a shot of excess fuel and sometimes it triggers the infamous Passlock theft light issue.

I don't see the check engine light on so I don't think any trouble codes are being registered. So based on that info, does anyone got some good ideas?

Thanks.

[manicmechanix]

Originally Posted by Newbu

I have changed the fuel filter and idle air control valve to no avail and I was going to put a fuel pressure regulator in but did not notice a fuel smell when the vacuum line was pulled off so I didn't install it (when the engine was cold mind you).

This right here is most likely your problem. The fuel pressure regulator is bad.

[SC2ner]

Mine has an issue similar to that. I have not looked into it too much just yet. When I figure it out I will let you know. The only 2 things I can think of right now off the top of my head is the ECT and CPS.

ECT- Engine Coolant Temperature Sender
CPS- Crankshaft Position Sensor (I would read-up on this one to understand why I suggest it)

Cps also can stand for cam position sensor so make sure if anyone ever tells you its bad they clairify which they mean.

[manicmechanix]

What it sounds like is happening is the fuel pressure regulator is bleeding off fuel pressure. This will really make the engine hard to start when cold. The fuel odor when you pulled off the fpr vacuum hose was a clue that it's leaking. During cranking this engine only gets one priming shot from all 6 injectors simultaneously until engine starts running and the cam sensor starts timing the injectors. By the way, To avoid confusion the crank sensor is properly abreviated CKP and the camshaft sensor is CMP I think. An ECT(or for that matter an IAT) would likely set a dtc. A CKP might not set a dtc but you would not have good spark.

[Newbu]

Originally Posted by manicmechanix

What it sounds like is happening is the fuel pressure regulator is bleeding off fuel pressure. This will really make the engine hard to start when cold. The fuel odor when you pulled off the fpr vacuum hose was a clue that it's leaking. During cranking this engine only gets one priming shot from all 6 injectors simultaneously until engine starts running and the cam sensor starts timing the injectors. By the way, To avoid confusion the crank sensor is properly abreviated CKP and the camshaft sensor is CMP I think. An ECT(or for that matter an IAT) would likely set a dtc. A CKP might not set a dtc but you would not have good spark.

Actually, if you read it again I said I did not notice a fuel smell when I pulled off the vacuum line to the FPR which was disappointing as it seemed the most likely cause. It had been sitting in a garage for a day before we worked on it so maybe any fuel smell would have left and I should check again after it has just been shut off? Would that make a difference?

[manicmechanix]

Originally Posted by Newbu

Actually, if you read it again I said I did not notice a fuel smell when I pulled off the vacuum line to the FPR which was disappointing as it seemed the most likely cause. It had been sitting in a garage for a day before we worked on it so maybe any fuel smell would have left and I should check again after it has just been shut off? Would that make a difference?

My mistake, I thought you did notice a fuel smell. Well the fpr doesn't have to leak into the vacuum hose to be bad, but I wouldn't replace it unless it actually checked bad. Other than that, you'd really need to hookup a fuel pressure guage to see where the pressure is and to make sure it holds. Sometimes the simple things like a dirty throttlebody, dirty fuel injectors,worn plugs (I know you only have 60k miles but i've seen the platinum tabs fall off before), plugged PCV, vacuum leak, etc. can make a car not start right. Sensors like the coolant temperature sensor can cause hard starting but normally it sets a code.

[JAMMBluesman]

If all the above post fail, replace the MAP sensor, It detects preasure in the Manifiold adjusting fuel usage when nec!!!

Hope this helps.

JAMM

[iwannagofast]

Originally Posted by manicmechanix

My mistake, I thought you did notice a fuel smell. Well the fpr doesn't have to leak into the vacuum hose to be bad, but I wouldn't replace it unless it actually checked bad. Other than that, you'd really need to hookup a fuel pressure guage to see where the pressure is and to make sure it holds. Sometimes the simple things like a dirty throttlebody, dirty fuel injectors,worn plugs (I know you only have 60k miles but i've seen the platinum tabs fall off before), plugged PCV, vacuum leak, etc. can make a car not start right. Sensors like the coolant temperature sensor can cause hard starting but normally it sets a code.

When the engine cools offs fuel pressure will significantly drop, making you think that's its bleeding off but in fact it is just the fuel contracting. a good test i did on my gf's car was i had her always prime the fuel pump before starting the car (two key cycles just to be safe) for a week or so while she was a way to school.she said it started up right away all the time.when she came back i went to start it and it took a 3-4 seconds to start with out priming the pump.i just walked over to her old blown engine that i replaced and swapped regulators.been problem free ever since.

[tjr19136]

your starter could also be the cause of this..........I had this problem with a 1994 saturn and my 1997 malibu............