4.3 chev fuel issues

[alotofcars]

I am a dealer and have ran accross this problem several times now, these vehicles wont start unless using starter fluid or fuel down the plennum and then thay run fine until they are turned off and they wont start again! It seems to be by reading this forum that weak fuel pumps are the #1 problem. All the posts I read say that the pressure needs to be at 65-66 at cold start. Please forgive me for asking this but is a completely warmed engine, (ran for several hours) considered a cold start simply because it is shut off then restarted? I ask this because these vehicles will not restart cold or warm without fuel assistance. Also, how common is it the pressure regulator? They vehicle I am currently working on is a 95 astro, but i have seen this problem also on two s-10 blazers one 95 and i think the other was a 01. How do i check the regulator? Thanks for any help and I hope I can contribute as well.

[Blue Bowtie]

The bare minimum pressure required to open the poppet style injectors is 61 PSIG, hot or cold. I've had a few that would actually start as low as 58, but most won't start below 60-61.

Low pressure can be due to several issues, and the fuel pump is very sensitive to voltage. Connections are critical. A fully charged battery is important, and sometimes jumping with a second battery can help to maintain voltage while cranking.

[old_master]

The absolute highest regulated fuel pressure, (if everything is operating properly), is achieved with: Cold engine, ignition in RUN position, engine off, and the fuel pump is running. In order to be classified as a cold start, the engine coolant temperature must be below 50°C (122°F) and within 6°C (11°F) of the ambient air temperature at startup.