Weird starting when it's REAL cold

My truck has started every single day this winter, even when we've had -15 temps. (Well, except for the day someone borrowed a few gallons from my gas tank - locking gas cap helps gas mileage!)

Ok - here's the deal. Every now and then, when the temp is below zero, (like this morning, about -12) when I start my truck it sounds like it's only hitting on about three cylinders. It shakes quite a bit and all you can hear from the exhaust is a loud whap-whap-whap-whap (GOTTA git rid of those stupid glasspacks!)

I did a tuneup a while back - new cap, rotor, plugs, wires, reset the timing. It only does this when the temp gets well below zero. Any guesses?




Senior Member
Lafayette, LA
Similar problems

Here's my similar problem...I live in the very far south..Louisiana and when it gets below freezing(more like 30 and below) my truck does the same thing except its from a Flowmaster rather than glasspacks...Sounds almost exactly as you describe it...only two things I can think of is that the viscosity of the oil(down here I use 20w-50) becomes much thicker and the engine shakes so badly trying to crank this oil troughout the engine...other posibility which may also be contributing to this problem is not enough backpressure--caused by this choking on thick oil-- to the engine which in my opinion might be a major problem when the choke is trying to work because it will hradly even idle.
Sound like a choke problem,like the choke pull-off is not working or not opening the choke enough.First thing I would do it clean off all the carb and choke linkages,and then give them a good shot of WD-40.You can manually observe the choke pull-off,when you start the engine cold.Take off the air cleaner and pump the throttle once,the choke should snap fully closed.Then have someone start the engine and see if the choke plate moves open about 1/8-1/4" when the engine starts.If it doesn't then either the choke pull-off is bad or not adjusted correctly.If you can see it moving then you can adjust it (you see a little screw on the moving lever,just above the choke cap).If the truck sputters cold then it probably needs more pull-off,or air.Turn this screw to open the choke a little further until it runs smooth.Also 20W50 is WAY to thick for winter use.At least go down to 10W40,if not 5 or 10W30.The thick oil is actually starving the engine for oil when it's cold,as it does not flow well.

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