2001 Chevy Express 2500 5.7l, 183,000 mi. Recent fuel pump replacement for no start low pressure. Now starting speed varies, one month after new pump. Backfires during cranking, takes 4-5 tries when a cold start, starts more normally when restarted after driving.
A new rebuilt starter on my 83 BMW 533i 87,257 mi acts the same.
Thanks for tip on new model OBD2 tool!
Got a fuel pressure regulator, will get a loaner fuel meter, lost pressure with old fuel pump, shall check again with new pump, can replace reg on spider inside intake cover. Will update, thanks!
Sounds like it is most likely a fuel issue like it’s flooding as it sits. If it has a serviceable fuel pressure regulator it could be the issue bleeding off pressure or a leaky injector staying open flooding the engine as it sits for longer periods of time. If you have a fuel pressure gauge you could leave it on when parked and see how much pressure loss you have
starter motor speed depends on battery voltage, so you might want to look at that.
backfiring would suggest a timing or ignition problem. 2001 means it's probably still uses mechanical distributor ignition. I would inspect that for arcing, and maybe replace the cap.
