What's up guys and gals, new the forum. I have a 93 S10 Blazer. 4.3 CPI. I've done a fuel pressure test on the pump and I'm not sure which way to go with the results. Priming the fuel pump I get 60psi from the pump. Almost instant bleed down to 20psi, then slowly to zero over only 5 minutes. I pinch off​ the pressure line after the pump is pressurized and I caught it at just under 60psi and it holds. So do I shoot for replacing the fuel pump?

 

thats the way I would go

 

nice, thank you

 

Before replacing the fuel pump.

What is exactly the problem?
My 94 has the stock fuel pump still going strong.
A myriad of things can cause fuel injection issues.

Example the TBI will not hold the pressure - it is meant to bleed down as soon as the pump is off.

So maybe you could start by trouble shooting.

- What is the issue that makes you check your fuel pressure?
- What engine option is it? (TBI / CPI)
- What are the conditions this happens?
- What are the general conditions of the car?

A lot more comes to my mind.

Good fault hunting!

 

So... Just finished fuel pump. All my research, testing and questions led me that route even though I've been skeptical about doing the job. Especially since I've done it before ( twice).

-Truck has 184,000+ mi.
It's condition is fair, and still fast passes emotions test.
- I have the 4.3 CPI "Spyder injection" I've had the fuel pressure regulator replaced in the past 60,000mi. that's when I did the second fuel pump as well. (The one today would make the third)
This system should hold after shut off at 55-65PSI
​​​​​​
- With the new fuel pump it starts instantly! Success! Ha... not so much. Before the fuel pump replacement, it would not start at all. But plenty of crank. When it was running over the last two months there was long crank, morning or night, hot or cold. The last two weeks, lots of hesitation during acceleration. It also started dying at intersections with a full stop. Friday morning trying to leave work it would not start. I work 5min from house, it died 4 times on my way there.

- Okay, recent replacements since Friday; Fuel pump, Plugs, wires, cap and rotor ( cap and rotor done about two months ago) and fuel filter. Ran strong for a small round trip of about 70mi.(that was Thursday, Friday is the day it died)

Beyond my initial tests, I have not performed another pressure test as of tonight. Not quite sure if I have any bleed down problems. I've double checked all my connections for leaks and found none.
Not sure which way to turn next.
Thanks for the input and anything else you have for me. It would be greatly appreciated

 

Only thing that comes to my mind right now:

Check rockauto in the literature section if they feature the "full" service manual not the Haines or Chilton.

The factory manuals contains the troubleshooting guide in the second book together with the full electrical wiring. Saved me a lot of trouble a couple of times.

Maybe worth throwing 200$ at the manual.

Good fault hunting.