2000 Hard Start
 

OK-
Lots of posts here about hard starting- Similar problem. Need some help to point me in the right direction. About a month ago as I headed to reserve duty, I put her up for the night and next morning she took about 4 cranks to fire. Ran fine the rest of the day. Few days later started getting an intermittantDTC. hAd Autozone run it. P0120 Throttle Position Sensor.

Replaced it. Code reset. Still have problem. Gets worse the colder it gets. When it is above 50 deg F I have hardly any trouble starting. Below 20 deg F and I can run down the battery trying to start. It acts as if it is starved for fuel. Engine cranks like it should fire right up.

Grabbed my Haynes manual and started checking a few things so I will list them and see if someone can take me further.

Here is background on the vehicle. 245K+, fuel pump replaced 30K ago, slight coolant leak from Intake manifold( I think) uses about 1 gallon over a 6-7 week time frame. No water in oil, no loss of compression, no smoke.

Checked EGR, cleaned it with throttle body cleaner. Seemed fine.
Cleaned Mass Air Flow with same. didn't appear to dirty.
Tested Intake Air Control valve w/ ohm meter.Readingswithin specs. Didn't pull it to clean though.
Battery cables show no evidence of corrosion. Vacuum lines all seem intact with no leaks.

Fuel Pressure at rail after setting overnight.
Key on: 53
Key off: 60
Key on again: 60
Crank:47
After start: 55
Stays at 55 even after warming to operating temperature.
Key off: 60 after pump cycles.
Left gauge on for 30 minutes-no visible movement on the needle.

Here is where I get confused though. I can apply jumper cables and she will fire first time like she is coming off the showroom floor. Coincidence? I have done it 17 days in a row, she will fire first time after overnight sit with extra juice. Put new battery 700 Cold Crank amps. No change.

So- since time and money are scarce, I don't want to throw parts chasing the wrong tail. Am I looking at a fuel delivery issue?, or is there some kind of cold weather sensor / electrical / ignition that I need to check? Any help will be appreciated.

Iwill post my results, just give some time as I work 12 hour daysand work on the vehicle is stretched out.

RE: 2000 Hard Start
 

Have you checked battery voltage before your first crank attempt, orchecked for amp draw on the battery with the key off. Just a thought since your comment about a boost first thing and it starts ok. i am not just trying to point out the basics but what about battery wiring what condition is it in.

RE: 2000 Hard Start
 

Devlon-
Thanks for responding. Sometimes the obvious is overlooked. I checked battery with
key off -12.98V
start draws down to 10.65V. Once running I have 14.14V across the battery so it looks like I am charging.

Not sure how to check for amp draw though. I put leads on both posts and ran the gammut of settings on amp side of meter. no readings with key off/on so I must not be doing it right.

a A friend told me his buick had a temperature sensor that caused the same problem so i am going to see if there is such an animal on the blazer. Electrical is not my strong suit.