I have a 99 blazer with a 4.3 and after the blazer sits for a little while it takes a 3 to 4 turns of the key to make it start so I checked the fuel pressure and it's ok but as soon as I shut the blazer off I notice that the fuel pressure starts to drop and after about 20 minutes the fuel pressure is at zero. I replaced the fuel pump 14 months ago. Would this most likely be caused by the fuel pump or by the fuel pressure regulator. does the fuel pump hold pressure in the sysytem like the pressure regulator does.

 

Could be either the pump or the FPR.

96+ Fuel System Diagnosis

You can also install a fuel pressure gauge at the fuel filter, effectively dead heading the pump which should result in 60+psi with the pump running and no leak down after the pump shuts off.

 

i have same problem with mine.i just replaced the catalytic conv.and all three sensors,bcause it was smelling like rotten eggs when it get hot.i thought maybe it was clogging up already cause its got 199858 miles on it.but come to realize it could be fpr.bcause i have hard time starting it too,black smoke coming out of tailpipe and running sh..y i have it dont know how to put it on.

 

What year is the vehicle? Rotten egg smell indicates a rich condition and the SES light should be on, if so, what DTC's are in memory. If you follow the steps in this link it will guide you to the problem. https://blazerforum.com/forum/tech-a...agnosis-23038/ Fuel pressure regulators rarely fail on 96 & newer: usually when they're replaced, it's due to a misdiagnosis. In the long run, it's far less expensive to properly diagnose the problem rather than blindly throw parts at it.

 

Mine is a 99 4dr.did all the tune up and still ran crappy.then this is what I did yesterday.ive got random misfire cylinders checked for vac.leaks too dont know what it could be.unless I take it to really do a diagnostic on it.