1997 Gmc Won't start When Very Cold outside

[-~Octane~-]

Hey Everyone,

I have a pretty wierd problem with my truck that has been at a service garage three times with them trying to figure it out. Being up in canada it can get pretty cold during the winter months. When the outside tempature falls below -20 Celsius (or there abouts) my truck will not fire. It sounds as if one cyclinder is firing but that is all. WHen the outside tempature is warmer then -20 C is fires up with out any problems. When the truck won't start, If you plug the trucks block heater in for two hours it will come to life. So far the service garage has told me that there is no problem with the fuel pressure to the injector and that the injector is fine. They replaced the coil and it didn't change the situation. they replaced the ignition module and it started but on newyears day it would not start again until I plugged in the block heater. I'm guessing there may be a broken wire somewhere that is pulling apart when the tempature drops really low. I never used to have this problem and My truck would start right up when the outside tempature was -37 C with out plugging in the block heater. The battery is new and the starter is new. If you bring the truck into a heated garage when it won't start and let it warm up it will start. I heard somewhere that a crank shaft sensor might have something to do with it.

-Octane-

[Jeremy-WI]

Do you change your fuel filter regularly? Do you use a gas line antifreeze- dry gas?

[leeder70]

does sound like fuel but you said it will not fire. hmmm. and you are sure its the fire??????
cause really sounds like fuel freeze up.

[-~Octane~-]

Hey guys,

Thanks for the input. I'm pretty sure it is not the fuel filter as the service guys said it was getting fuel and that there wasn't any spark. PLus if you plug in the Block heater (warms engine coolant to warm oil that makes starting the engine easier) it will start in a 1-2 hours. Since it will start after it's plugged in i couldn't be the fuel filter as the filter is not being warmed up at all.

I was thinking a crankshaft sensor and the service guys think that is the next thing to check... Strange anyhow..

Thanks again.

-Octane-

[leeder70]

let use know what it finally ends up being ..................interested
thanks

[Slugbug]

My 97 GMC has the same problem.

This may sound goofy but I was thinking of blowing warm air on the crankshaft sensor with a heat gun or blow dryer to see if I can trick it into thinking the temp is warmer than it is.

thanks.

[ridered]

why not just plug the truck in at night I live in NJ and I plug mine in around 10:00pm every night at 6:00am it starts faster runs smother and almost instant heat for clearing the windows and less warm-up time = less wasted gas.(just my2cents)

[boydo]

This happens to my truck under the exact same surcumstances. I have no block heater but I put a small electric heater aimed directly at the throttle body and it starts without issue. We can't be alone on this problem so hopefully someone has an answer. Mine will fire for a split second and then die almost as if a choke problem in the older carberated style cars. In my opinion it must be something up at the Throttle Body that tells the truck what to do with fuel and air in accordance with the outside tempreture. Any info would be helpfull. There is a Idle Air Control Motor and a Throttle position Sensor mounted to this unit could it be one of these items? Also down by the exaust manifold there is a Engine Coolant Temperature Sensor that may be the cause Thanks Boydo