Chevy Suburban 1997 1500 won't start when Cold

One possible reason for this could be a faulty engine coolant temperature (ECT) sensor. The ECT sensor tells the engine control module (ECM) the temperature of the engine coolant, which is used to adjust the air/fuel mixture for starting. If the ECT sensor is faulty, it may be sending incorrect temperature readings to the ECM, causing the engine to not start in cold weather.

Another possibility could be a weak fuel pump check valve. When the fuel pump check valve fails, it can cause the fuel pressure to drop when the engine is turned off, which can cause hard starting in cold weather .

It's also possible that the battery is weak and not providing enough power to start the engine in cold weather. Cold temperatures can reduce the battery's cranking power, which can make it difficult to start the engine.

I would recommend taking your vehicle to a certified mechanic to diagnose the issue.

Forget about the fuel pump, completely for now. THAT is not the problem. Think on what you've told on the situation. Been getting worse hard to start as the temperature drops. Now here is the way the system works: Turn the switch on, the computer automatically jumps in to do what it does best, operate your vehicle/engine, by taking the impulses from ALL sensors, and setting the engine to a position that it will start and run properly. One of those impulses come from the temperature sending unit in the engine coolant system and, because it's cold, tells the computer to place the engine into "cold start" mode. Now you crank on the engine and it starts easily, because the temp sensor sent said pulse to the computer. Once the engine is warmed, this sensor sends a pulse telling the computer it is now warm and places the engine into "normal run" mode.
As you can see, this scenario is with everything in proper working order. With your scenario, the engine will not start when cold. Therefore the computer is NOT getting any kind of impulses from the temperature sending unit/sensor. Meaning it's either bad or just disconnected and out of the system. These days you have to at least be as smart as the computer and diagnose things the way I do. Not saying I'm smarter than the computer, just that I outsmart it when needed. Now, Fix your Chevy.

The engine is overheating, check the anti-freeze level when cold, refill and repair the leaks. Check belts that drive the water pump.

If that bottom hose is cold, it sounds like the radiator itself is not circulating.

Sounds like the automatic choke control on the carburator is shot! It is stopping the proper flow of gas from getting to the engine...replace it! Also make sure you have recently replaced the fuel filter; moisture in the gas will stick to the filter and freeze up making it hard for gas to get through!

Possible bad cold start valve or the sensor that tells the valve to activate when cold. Start by replacing the cold start valve first.

mcdevito75 here, It could be the fast idle sensor, this acts like the old chokes that enrich the fuel mixture to keep a cold engine running a bit faster at a cold start. Have your local shop check it out.

Maybe your throttle position sensor is goin bad

i had the same problem, i changed out the complete front control panel and now it works like a charm.

The engine temp sensor is located at the back of the engine above the gearbox. It is usually green with 4 wires if there is only one sensor, or 2 wires if there are 2 seperate sensors. make sure engine is cold, remove plug, then slide clip out and pull sensor free.

TL