2001 jimmy won't start below 30 degrees

2001 gmc jimmy will not start below freezing. will crank fine just won't start. Pump runs for couple of seconds but no pressure at scradder valve. if i spray starting fluid into carb it starts and runs fine the rest of the day. Once car starts i have fuel pressure. i had fuel pump replaced ran fine until temp dropped, now won't start again (dealer charge 500.00 to replace pump) What else would cause no fuel pressure before engine starts?
thanks
George

Well thanks for all the help and info. I changed the coolant temp switch, and car is starting at cold temps and is running fine. I bought the parts at the local GM dealer because i've not had good luck with elec parts from autozone. The fuel pump replacement took care of a check engine light problem i was having. now the only problem i have is a P0440 code. EVAP canister? But not too worried about this, car runs fine. May start a new thread for this just to see if anybody else has this problem and knows of a fix.

thanks
George

Blocked fuel filter or a battery that has insufficient current to have the pump properly prime the system.

battery replaced last year. Just replaced fuel filter about an hour ago. temps are at 22 degrees now. will see in a couple of hrs if that works

Well Its Christmas Morning Car sat out all night in 10 degree weather and it;s a no start! Spins fine just won't start. ??? Thought i had it yesterd day was starting real good, until sat overnight.

well mine has to be jump started every morning. I have a 98 jimmy. Once i jump it it runs fine and starts fine the rest of the day. I just had the fuel pump replaced as well. It does it when the temp drops cold at night too. I have no idea how to fix it, but if you figure it out, please pass it along to me...ty, Donna And Rickey

battery replaced last year. Just replaced fuel filter about an hour ago. temps are at 22 degrees now. will see in a couple of hrs if that works

Well Its Christmas Morning Car sat out all night in 10 degree weather and it;s a no start! Spins fine just won't start. ??? Thought i had it yesterd day was starting real good, until sat overnight.

Don't think because the battery worked last year that it is guaranteed to work this year.

Check the battery voltage with the engine off. It should be around 13.4 volts or so. Anything less than 12.8 and your battery is weak.

Don't think because the battery worked last year that it is guaranteed to work this year.

Check the battery voltage with the engine off. It should be around 13.4 volts or so. Anything less than 12.8 and your battery is weak.

Yes i thought that too. But i tried to start with my charger connected and on boost, so i'm sure i had enought voltage

Couple of things i've been trying;
1. heating different components in the morning with my heat gun. Seem to start a little better when i heated my MAF sensor?? and the sensor next to it on the intake?
2. Noticed that the car didn't start until i released my key?? Almost like somthing wrong with the ign switch?? But everything else works.

Did you check the battery voltage yet?

A bad battery will not start the truck properly even with a charger attached.

Check the battery voltage when off and when running.

OK batt is 12.8 off and 14.6 while running. So should a new batt resolve the problem?

Well had batt checked at Auto Zone, they said it was ok!
32 degrees this morning car started right up. And has been running good.
??????? Don't know what to check next.

My wifes 1998 has the exact same problem. It will not crank in 35 or below weather. In my case it is NOT battery related. When I get this figured out I will let you know........

thanks, i don't believe mine is battery related either. mine will crank but just won't start. But it started and ran fine all day today. Temps were in the 20's????? I am going to leave it out tonight and see what happens.

So it warmed up and it started?

That is a battery condition.

The lower the temperature , the lower the voltage and current output from the battery.

This will lead to lower pump pressures which could be below threshhold.

Well sat out all night, temps were in the teens. Started the first crank???? The only thing i did yesterday was disconnect the maf sensor and the small sensor next to it so i could remove the air filter cover and clean the air filter. Started car back up and it ran very rough thought is was going to stall. did this for about 30 or 40 secs then all of a sudden it idles perfect. we drove it all day returning xmas gifts and it ran fine. Blazer thanks for all the input, if this continues to happen I'm about ready to try a new battery any suggestions on size and type? thanks
george

My wifes is currently at my buddies shop getting looked at. Its NOT battery related but he thinks it is indeed MAF related. I should know by lunch.... :-)

Will be waiting to hear results!

Sometimes, when the batt is fine, the fuel is fine, and the ign is fine; there is only a couple things left. You might not be getting spark. Check spark plugs, cap, wires, etc. Just a thought.

Ok.... results.... there is a thermal switch that runs off coolant temp that sends a signal to the Maf. It was bad according to my mechanic.

I finally broke down and bought a Haynes manual. Do you know the part number of the part they replaced?