Hard start on 2004 Buick Park Ave

billr

wrench
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#46
OK, I got it... this is *only* a starting problem. When you say "it won't turn over", you mean it won't fire, but it always cranks, correct?

You really need to use live-data to get this effort back on track. Although the fuel pressure was the most likely culprit, but seems OK, other suspects are the ECT sensor, TP sensor, and IAC valve. Those can be checked with just a multimeter, but the live-data will make it much quicker and easier.
 
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#47
Yes that is true. It always cranks but doesn’t always start. What do you mean when you say live data?
 

nickb2

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#49
5 psi off is enough to cause problems. You really want 53 or more. It should not drop below that. Try removing the vac line to regulator, does FP rise in psi?.

If you have a phone or laptop, something cheap like this should get you good live data https://www.amazon.ca/ELM327-Bluetooth-Diagnostic-Interface-Scanner/dp/B07T4WFJ4M/ref=sr_1_12?crid=1ADHTP9XQPUQL&keywords=elm327+bluetooth&qid=1571261985&s=automotive&sprefix=elm+327,automotive,163&sr=1-12

But if you are willing to pay a few bucks more for some bi directional as well, this unit is sweet and cheap. Will pay for itself in no time on this car. It is like having a OEM tech 2 on your laptop. https://www.amazon.ca/VXDIAG-Tech2Win-Diagnostic-Programming-System/dp/B06XDHF3XX?th=1