1996 Suburban - starts then dies.

[divorced]

1996 Suburban K1500, Vortec 5.7, 4L60E.

When it's cold outside, and the engine is cold, I will start the engine and it will only run for about a second then die. I can restart it and hold my foot on the gas pedal, kinda "keeping it alive", until it warms up and then it sometimes idles fine. Sometimes it idles around 1,800 even at operating temperature.

Where should I start?

And just a question so I know how it works - does an idle air control valve do anything on a cold engine, or does the engine run off of the pre-programmed deal until it warms up?

 

[blazin_blazer]

temp sensor

 

[divorced]

Is it a coolant temp sensor? And is it the one on the intake?

 

[longbedder]

I agree that it could be the coolant temp sensor (yes, it's on the intake).

To answer you questions, the IAC valve is in use at cold idle.

The best way to diagnose fuel injected engine problems (IMO) is by getting data from the ECM. In your case that would be OBDII.

 

[divorced]

Awesome, thanks for the info so far.

I'm guessing the $60 code reader from Wal-Mart isn't what I need?

I've had a CEL twice before, and the Chevy dealer and AutoZone both said it was the 02 sensor; bank 2, sensor 2. The Chevy mechanic told me that sensor does nothing to help the engine run, so I haven't worried about that.

I currently have no CEL, although I understand (I think) that a sensor could still be defective and not have a CEL.

I read that a scanner can make the IAC (and other components) operate while still on the engine, so they can be easily tested. I'd hate to imagine the cost of that tool...



.

 

[blazin_blazer]

we just had the same problem on a '91 burb, the ecm said o2 sensor&tps was bad, we replaced them...put new injectors on it b/c 1 of them was drizzling/dripping...wasn't a good cone shape under the timing light, new 1 did same thing, we told a local mechanic what was happening, 1st thing he asked was had we replaced the temp sensor, we hadn't...replaced it and motor ran better than it ever has...he told us the temp senser was telling the ecm it was like -20*, causing the motor to run real rich(so much the injector was drizzling, he said that was his biggest clue, so look down the tbi and see if they maybe dripping

 

[divorced]

I'm not sure if the injectors are that easy to see on the Vortec motors, but the temp sensor is cheap enough to try anyway. I'll have it hooked up to a computer before I spend much more than that though.

Thanks.

 

[5280k5]

A Vortec motor shouldn't have an IAC b/c it's not a throttle body/speed density system. The injectors are inside the upper intake and are more likely to stick closed than open and cause a misfire rather than a stalling problem. I would have someone look at your fuel pump, either with a pressure gauge or use a multimeter to measure the pumps amp draw to eliminate this a possible suspect if the coolant temp sensor doesn't fix it.

 

[divorced]

Funny you should mention it... I had the pleasure of replacing the fuel pump just a few days ago. Luckily it broke at work where we have some forklifts and a heated building, so that made dropping the tank fairly easy. Before the fuel pump went out, I had a bad surging/missing when driving sometimes and the "start and die" problem. The new fuel pump seems to have fixed the surging problem, but the start and die problem still exists