Difficult to start car

[cchase]

Hi all,

Our 2002 Malibu has developed an annoying habit the past few weeks - hard starting.

It cranks fine, catches, but then immediately stalls: sometimes. Sometimes it never really catches, or partially catches.

Today I got out the spark tester and fuel pressure gauge. Fuel pressure was still fine from driving last night when I hooked it up, and immediately pops up to 55 psi when the key is turned to the ON position.

Crank the car, the spark tester flashes away properly, the fuel pressure sits at 55 psi, and nothing happens... or it catches and immediately dies.

If you flutter the gas pedal while you're cranking it, you can KEEP it running when it catches for that second, but it's a little like keeping a cold chainsaw running, you have to blip the gas to keepit running for a few seconds. If you do that for a few seconds, say 3 or 4, then you can stop and it will stay idling.

It has no drivability issues, once you can get it to stay running, it runs fine. No fuel economy issues, no codes, no other symptoms.

Any thoughts?

I'm going back out to start running down my mental checklist but before I offer any of my own suspicions I was hoping to get some fresh insight.

Thanks in advance!

 

[The_Jeff]

The gas pedal thing defies my first thought, passlock/ passkey security freaking out. When that happens the car catches then shuts itself down after 2 seconds.

You might want to mod your passlock anyway while it still runs, it involves a google search and cutting the yellow wire, potentially splicing a resistor in. N-bodies are notorious for this failing.

It could also have a flaky TPS that supplies a plausible voltage that's not idle voltage. This will tell the computer, nah, don't bother keeping an idle. But it won't toss a code and once a couple seconds pass other sensors are online.

 

[cchase]

We had the Passlock/Theftlock thing happen once. That will just let the car crank forever, but it's also accompanied by the idiot light on the dashboard.

 

[panther427]

Crank position or cam position sensor also plausible.

 

[SIXSPEED]

The idle air control valve (IAC) comes to mind.

http://www.wikihow.com/Check-an-Idle-Air-Control-Valve

 

[NHGUY]

Crank sensor/Idle air motor.

 

[Warstud]

Try turning the ignition on and leaving it on for 10 minutes. Then turn it off and try starting it.

 

[TFB1]

Originally Posted By: SIXSPEED
The idle air control valve (IAC) comes to mind.

http://www.wikihow.com/Check-an-Idle-Air-Control-Valve


I second that one... Could just be gummed so is hanging closed when cold...

 

[Drew99GT]

My Toyota had the exact same symptoms a year ago and it was a dirty IAC valve; you might try running intake cleaner through the valve or research if that is an effective/safe means of cleaning GM IAC valves.

 

[Oldmoparguy1]

My 89 Turbo Caravan does that. Idle air control motor. I haven't driven it in several years, but it starts and runs fine in July weather.

 

[cchase]

Well, everyone picked the same thing I had in mind.

Replaced IACV (not worth wasting the time trying to clean it out) and works great. Interestingly the original one did not look dirty at all.

Thank you for the quick responses everyone!