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chevy venture cold start problem
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richmiss
New User
Mar 10, 2010, 9:34 PM
Post #1 of 3
(7413 views)
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chevy venture cold start problem
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2000 chevy venture
3.4l 145,000 mi
My 2000 Venture has a starting problem. It won't start when it's cold outside, below about 40 degrees. The engine turns over. I put a spark test light on and got no spark several different times. A local mechanic replaced the cam sensor and ignition module and told me to come get it, then called 5 minutes later and said it was doing the same thing don't come. He then replaced the ecu with another used one flash matched to the van. I got it and 7 days later it wouldn't start again. So I then took it to another mechanic who said the fuel pump was weak and pulled too much juice when cold so I need a new one. Maybe I do, but I don't understand why I wouldn't have spark if it is the fuel pump. Does the computer sense the fuel problem and not send spark or could it be another problem? The van starts every time when it's warm outside. I've got $600.00 into this problem already and they want $900.00 to do the fuel pump. I live in florida, so this problem doesn't happen all the time.
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Sidom
Veteran
/ Moderator
Mar 11, 2010, 1:29 AM
Post #2 of 3
(7408 views)
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Re: chevy venture cold start problem
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It's always tough trying to diag a intermittent and double tough online without being able to see the vehicle.
So just going off the info you provided that it's a straight no spark issue, I would have to pass on the fuel pump. About the only way the pump assembly could cause this was if the FTP sensor was shorting out & pulled down the 5v ref voltage and while not impossible, is rare, plus would be easy to diagnose ( at least the missing 5v ref, finding the problem would be a different story due to the rarity)
One common area I would probably check during the failure would be the crank sensor, this is a common failure area.
I really don't want to second guess the techs due to so much missing info. I don't know if there was any codes, any helpful scan data. How long the no start lasts. If it's only a few minutes with no codes then this is going to be very hard to trace down. You are only going to have 1 or 2 shots at best and are going to have to have your equipment set up & ready to go if you can't get any useful info, then you need to figure out what other tests you want to run, set up for that & wait for you next opportunity.
With the parts that have been replaced its possible they were out of range enough on the tests the tech ran and due to the complaint of the problem felt he had found the problem. With the fuel pump, sounds like the tech current ramped it & got a bad pattern while that's a decent test you do have to be careful how you interpret the readings. I've seen brand new pumps out of the box with hashy readings & low amp draws that work fine ..
I know some of this isn't what you want to hear but with intermittent problems, it's just the nature of the beast.. A lot time it just isn't a quick cut & dry diagnosis but takes time...........
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DanD
Veteran
/ Moderator
Mar 11, 2010, 5:40 AM
Post #3 of 3
(7406 views)
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Re: chevy venture cold start problem
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I second, holding off on the fuel pump; any pump can look bad amp draw wise with low static battery voltage (engine not running or being charged).
Does the computer sense the fuel problem and not send spark
No it’s the other way around; if the computer doesn’t sense an rpm signal (spark), it will not authorize the fuel pump.
Going back to battery voltage, especially during cranking; has it been tested?
I have seen this a number of times, up here during the winter; that an engine will crank and crank relatively normal but the engine will not fire, due to low battery voltage.
What I mean is that battery voltage maybe dropping down to 7 or 8 volts and staying there, during cranking. That’s enough to keep the starter motor engaged (yes cranking a bit slow) but not enough voltage to allow the computer, ignition module, injectors and fuel pump to function properly.
This could also be why the Tech sees high amperage draw on the pump; low voltage will make an electrical motor draw more amps. (Ohms Law)
Sometimes we all forget the basics and get electronics stuck in our brains.
Make sure the battery can and will pass a load test when the battery has been sitting in the cold for 10-12 hours.
This may sound like a dumb idea but have the Tech stick the battery in their beer/lunch fridge over night and then load test it in the morning, before any temp can get to it?
Dan.
Canadian "EH"
(This post was edited by DanD on Mar 11, 2010, 5:42 AM)
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