Cold Weather Starting

[4L80]

I have one more issue that has been bothering me for years that hopefully someone can help me with. In 2011, I bought a pampered 1993 Chevrolet K2500 5.7 that came from a fire department near Detroit. It had spent its entire first 18 years indoors and now for the last five years has been subjected to slightly harsher Northern Ontario winters. My problem is, as soon as it drops below 32 degrees fahrenheit, it turns over great but is reluctant to fire. I have done a tuneup, plugs, wires, rotor, cap and air filter, but no significant improvement. I have installed a block heater, and if I plug it in, it starts perfect. But I know that I shouldn't have to plug it in at 28 deg fahrenheit. The one thing I have been suspicious of for a long time, is that my fuel pump takes 20 seconds to cycle to build up pressure when you first turn your key on. Is there someone out there with a similar vintage 5.7 that could confirm if this is a normal cycling time?

 

[michael hurd]

As far as how long the fuel pump should run when the key is cycled? Not sure on that, I don't have a TBI, but I would change your fuel filter, if you haven't already.

When it doesn't start, do you have fuel spraying from the injectors? IE: open the breather and have someone crank it over.

If you don't, suspect thick oil / restricted passage to the oil pressure switch behind the distributor, or bad oil pressure switch. You can bypass that to try starting it cold.

If you do have fuel, you may have a problem with the coolant temp sensor near the thermostat housing. These can be tested, I am sure with a bit of searching you can come up with a chart of resistance vs temperature.

Clean grounds, especially the ones near the thermostat housing.

Hope that helps pinpoint what some of the probable causes are.

 

[BIG_KID]

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[4L80]

Thanks BIG_KID for the chart, and thanks michael hurd for the list. I will start with the fuel filter and work my way through.

 

[1995sierra305]

Could also be Injectors leaking down. Causing your low pressure on start, or a fuel pump slowly on its way out. As for oil pressure switch, highly doubt it. Coolant temp sensor is a possibility. But I'd check your injectors first.

 

[4L80]

I should add that this 1993 truck has been doing this since the first winter in 2011 when it only had 20,000 miles on it. Today it has 63,000 miles. If an injector leakage can happen at any time, I will add it to the list, thanks.

 

[tanman_2006]

My fuel pump takes about 2 sec after I put in the vortec pump, mine is a 94 C3500 with 113,000.

I still have a hard start though. I let it turn over 2 times then hit the throttle and it will fire. Then I have to slowly back off the pedal or it won't hold Idle. After that it's pretty much good for the day.

Once it's not cold as heck I'll start my back probing.

 

[1995sierra305]

I should add that this 1993 truck has been doing this since the first winter in 2011 when it only had 20,000 miles on it. Today it has 63,000 miles. If an injector leakage can happen at any time, I will add it to the list, thanks.

It may have had only 20k . But those trucks see a lot of idle Time, and also a lot of start to move then stop. Miles really don't mean anything. It's almost a 24 year old truck lol.

 

[kennythewelder]

There is a very easy way to figure out if it is a lack of fuel issue. before starting, remove the breather cover, and poor a little bit of gas into the TB. If it fires up quicker, then it is starving for fuel. A failing fuel pump will cause a lack of fuel pressure, and cause hard starts. As long as it is taking (20 sec.) to precharge the fuel pressure, that very well could be a week fuel pump. A pressure test will tell you if it is within spec. You can rent a FP tester at autozone. You have to buy it, but will get all your money back when you bring it back. I would not put a Vortec pump in your truck. A TBI runs less than 20 PSI , where a Vortec pump puts out over 60 PSI.

 

[4L80]

Thanks Kenny, It is supposed to warm up slightly in the next couple of days so I will get the fuel filter installed, try it, wait, then do the little gas to the TB and see if it fires.