2001 Suburban - cold start problem

[Doubeleive]

keep it basic fuel-air-spark.
you know you have fuel, so that leaves air and spark
but you should confirm you have at least 50-65lbs fuel pressure with key on (when cold, before first start)

 

[DCT]

keep it basic fuel-air-spark.
you know you have fuel, so that leaves air and spark
but you should confirm you have at least 50-65lbs fuel pressure with key on (when cold, before first start)

Yes, fuel pressure confirmed.

Must be sensor somewhere. TB is clean. Intake boots ok. Maybe MAF doesn’t like cold. It’s the original.

 

[drakon543]

Unfortunately I don’t have access to a Tech2.

Are you talking about the coolant temp sensor? If so, I replaced recently with an AC Delco.

dont need a tech 2 for the basics even with a live data scanner you can buy an innova from most advance auto parts stores under 100 bucks. they work well enough for anything ive ever had to mess with. as far as the sensor itself some vehicles have 1 sensor some have 2 im not sure on yours. your other temp sensor would be your intake air temperature sensor. sometimes they are part of the mass air for sensor. they can also just be a separate sensor somewhere else on the filter housing or the intake tube or even somewhere on the intake manifold. on your truck it appears to be a part of your mass air flow sensor. i suggest getting a can of maf specific cleaner from your local autoparts store. remove the maf and spray it down heavily. leave it inside the house to dry for atleast an hour before you attempt to reinstall and plug it back in. while your doing this unhook your battery to allow the ecm to clear its tables. when you go to start the truck up if it does start it might stall the first time or stumble. just let it stall or stumble restart if needed and let it relearn with a clean maf and it will smooth out on its own.

 

[Doubeleive]

Yes, fuel pressure confirmed.

Must be sensor somewhere. TB is clean. Intake boots ok. Maybe MAF doesn’t like cold. It’s the original.

When you cleaned the throttle body did you also clean the iac? (it is attached to the drivers side of the throttle body)

 

[DCT]

When you cleaned the throttle body did you also clean the iac? (it is attached to the drivers side of the throttle body)

Yes.

I haven't tried swapping out the MAF.

 

[jasonb100272]

Need help please. I searched the forums but no luck.

When the weather is below 50 degrees, engine will keep cranking but not start. This happens only in the winter. The rest of the year the motor runs perfect.

After about 10 tries, the motor will finally turn over and start. Once the motor is warm, it will re-start no problem.

Engine is a 5.3L, 300k miles, but has a new starter, 3 year old fuel pump, new intake manifold gaskets, new plugs and wires, and new air filter. No mods to the engine, all stock.

No vacuum leaks, I changed all vacuum hoses. Catalytic converters and O2 sensors all good, I just passed smog check. I checked fuel pressure, no leak down overnight, and pressure is good during start up in the cold weather.

I don't know what else to check or replace. Thanks for the help and suggestions.

crank shaft sensor. Any auto store or rock auto . I would use a Delphi about 55 shipped. Google replacement. If you are fairly mechanical you can do it. This is comon especially if its a hit / miss starting problems but they can fail completely. But see if you hold the gas pedal down when starting if it starts faster? Then it could be a fuel or emissions problem. coil packs? Are there any codes? vapor canister purge valve. Good luck.

 

[DCT]

crank shaft sensor. Any auto store or rock auto . I would use a Delphi about 55 shipped. Google replacement. If you are fairly mechanical you can do it. This is comon especially if its a hit / miss starting problems but they can fail completely. But see if you hold the gas pedal down when starting if it starts faster? Then it could be a fuel or emissions problem. coil packs? Are there any codes? vapor canister purge valve. Good luck.

I’ll try the gas pedal. Spark and fuel are good. I will research the vapor canister. Thanks

 

[Jeff Shriner]

OK HERE IS A THOUGHT, HAVE A CAN OF STARTING FLUID READY FOR WHEN IT CRANKS AND DOES NOT START, WHEN IT HAPPENS GIVE IT A SQUIRT. THAT IS THE ONLY, REPEAT ONLY WAY TO KNOW THAT IT IS NOT FUEL RELATED IN ANY WAY. IF IT STILL DOES NOT START THAN YOU CAN MOVE TO SPARK BUT THERE IS VERY LITTLE IN THE WAY OF SENSORS OTHER THAN CAM / CRANK THAT CONTOLS SPARK. IF IT DOES START WHICH WOULD BE MY BET THAN YOU ARE STILL A WAYS FROM FIGURING THE PROBLEM OUT AND IT IS HONESTLY VERY UNLIKELY TO BE A SENSOR. I HAVE CHASED THESE ISSUES DOWN ON MULTIPLE BRANDS AND ALMOST ALWAYS ENDS UP AT A BAD CONNECTION OR BAD GROUND.

EITHER WAY THROWING PARTS AT IT WONT HELP IF YOU DONT KNOW THE DIRECTION TO GO.

OR SELL IT TO SOMEONE THAT LIVES IN ARIZONA LOL

 

[ScottieTooHottie]

I like the temp sensor diagnosis.

Turn the key to run and listen for the fuel pump to spin. Try that ten times. Better spin every time. Don't start the engine.

If the pump spins, check for spark at one spark plug. If no spark, my first guess is the camshaft position sensor at the top rear of the engine. But I think that one throws a code. On mine, the wiring to the connector on the harness was frayed just enough to let it start, but not always. Run to Autozone and borrow a scanner if you don't have one.

 

[Doubeleive]

temp sensor is extremely unlikely in my opinion