no cold starting '00 sonoma

[motcher41]

'00 Sonoma SLS Ext. Cab 4X4 4.6 Vortec V-6 Engine Code:W

In temps under aprox. +15 degrees truck will not fire. It does not have a block heater, or do I have a place to plug one in if it had one.
Has good spark with plugs out, enough fuel is getting to the cylinders.
Battery has a good charge. Has new plugs. Never any check engine lights.
Once outside temp rises to above +15 degrees it starts with no problem.

Anyone ever ran into this, or a clue to a possible cause?
Any help would be great.

Sonoma....not a Northland Truck

[rlith]

Hmm... Sounds silly, but when was the last time you changed your fuel filter? Debri could be freezing in it... For giggles as well, get some water remover from the autoparts store and run it through the system.Water could be freezing inside and clogging the sending unit. When is the last time you did a full tune up on your truck? (wires, cap, rotor, plugs, pcv, etc..)

Does the truck crank at all at those temps?

[blazee]

This was taken from an article about CPI (92 - 95 Vortec) and CSFI (96+ Vortec):


"From a service standpoint, however, this system has its weaknesses. There are two problems that have ended up being pattern failures. First, the system runs at higher fuel pressure than what we are accustomed to seeing, 56-64 psi. The poppet injectors will not open reliably with much less than 54 psi. I believe it was the Vortec cold hard start problem that was the inspiration for the concept of checking fuel pump rpm by means of the low current probe and the lab scope. The problem occurs during cold mornings when battery voltage is not what it might be. During cranking, voltage to the fuel pump drops. The rpm and consequently the pressure of the pump goes below the level necessary to open the poppet valves. Some of these hard starters took months to diagnose because a tow truck driver would hook up his jumper, and voltage would rise high enough to gain the extra two or three pounds of fuel pressure. Or, the vehicle would be towed in during the cold morning, but by the time the shop got around to checking the vehicle, the ambient temperature had warmed enough to kick up battery voltage, and the thing would start. Techs who were in the habit of not looking stuff up would see over 50 psi on their gauges, and, of course, that had to be enough! Sharp guys like Jeff Bach (current probe guru) and Jim Linder (the injector guru) learned how to scope the fuel pump waveform with the lab scope and calculate pump condition and rpm, almost to the point of being able to predict what day of the year the vehicle would fail to start!"




Try spraying a little starting fluid in the intake, if it starts, then you have a fuel problem, simply replacing the fuel filter may help.

[motcher41]

Well I thought about the fule filter but it gets plenty of gas. I'll change it anyway though. They aren't that spendy and on this model it is pretty easy. As for a full tune up. It hasn't been done since I purchased it 2 years ago. I will do that as well. Also it does crank over.

Thanks for the reply.

Originally Posted by rlith

Hmm... Sounds silly, but when was the last time you changed your fuel filter? Debri could be freezing in it... For giggles as well, get some water remover from the autoparts store and run it through the system.Water could be freezing inside and clogging the sending unit. When is the last time you did a full tune up on your truck? (wires, cap, rotor, plugs, pcv, etc..)

Does the truck crank at all at those temps?