Problem: engine starts erratically, especially in warm weather.
CMFI Requires: KO/EngOff 58-64.
Eng running: decrease 3-10psi.
I Have:
KO/engOff:55 psi
Eng Running: 52 psi

I would've checked voltage to the pump next to make sure that it didn't drop more than 1.5 volts, ".5 idealy". I didn't though. I didn't have a friend to help at the time.

Instead I worked on the four by four issue i've been having.
%the vacuum actuated module below the battery was FUBAR'd. The spring in the actuator was turned ninety degrees and not pushing on the cable going to the differential. There was also fluid in the vacuum line.

I ended up tearing apart the front end. To be Continued.

 

Welcome to the forum!


1996 has CSFI, (Central Sequential Fuel Injection, it has 6 injectors). 1995 and older has CMFI, (Central Multiport Fuel Injection it has one injector). The two systems have different specs, diagnostics, and repair procedures. All pressure readings and leakdown time is done with the engine off. Engine running readings are meaningless on CSFI and CMFI systems. Your Key ON, engine OFF fuel pressure at 55psi is too low, and it will cause problems, guaranteed. Not sure where you found those specs, (Chilton/Haynes??) but they are incorrect for both systems. Checking fuel pressure and leakdown at the service port alone is not enough to diagnose the fuel delivery system.
This thread explains: https://blazerforum.com/forum/2nd-ge...eakdown-88305/
Post all 4 readings, and we can help you analyze the fuel delivery system.