Random long cranks?

[Armalite]

It seems when the temp changes randomly like we been having here in NJ my truck randomly takes sometime to turn over. For instance this morning (not plugged in) It was in the 30's, wts light came on like normal. Started fine. Drove it to work and let it sit for 6-7 hours. Went to start it. The wts came on like normal but it would crank over for about 10 seconds and not start. I don't dare to keep cranking. So I stop wait a few seconds and hit the glowplugs again and it fires up.

-Wts light works fine
-Tach moves
-Smokes white/cold

It's random. Seems to happen in sudden weather changes when cold. I'm planning to check and change the oil tomorrow. When is it best to check the Hpop res? Cold or warm matter?

I havent been able to test the glowplugs but I did test the relay and its working as it should.

[BigFuel]

You can check the HPOP res. anytime. If you just shut the motor down then the Res. should be pretty full. If the truck has been sitting for a while the level should not have changed too much. If it looks like the level has really dropped then you need to look into why. Check your battery charge too. The cold does wonderful (as in bad) things to batteries.