Have a 98 blazer 2dr.
I'm currently having issues with it starting which have worsened after changing out the fuel pump... So I put the old pump back in that was working better than the new one was...

So the unique issue is that after replacing my old pump. I turn the key on and I can't hear the pump. If I put my hand on the top of the pump, I can feel it pumping for the 2 seconds that its supposed to. I check the fuel rail and no fuel is present. So... What am I missing. The old pump was way louder before. So not sure whats going on.


The previous troubleshooting tests with the tank removed showed that the pump was pumping fuel. I wired some cables straight to the pump while the pump was in the tank. New pump flowed a little, old pump pumped with more force. that is why I put the old pump back in.

I have changed out the fuel filter.
I can feel the fuel relay move when the key is turned on.

Have other issues that I wont go into it right now, but may if this thread goes on further.

 

What type of starting issue are you having. More detail would be great.
What brand fuel pump are you using and have you tried?
What was your fuel pressure and leak down test numbers?

 

At first, it was start after the 3rd or 4th try.
Then as it progressed, it would start with starting fluid
as long as it was warm, it would start again
Then it progressed to only starting with starting fluid.

I tested the pump and it was slightly below specs. Don't remember what they were.
The pump I installed was a TOPSCOPE FP3954M fuel pump. I have since reverted back to the original pump because the new one would not let me start it. Then the old one isn't either. So there must be some other issue causing it.

Don't remember the original fuel pressue numbers. I think it was 3 under specs. Not sure about leak down. Currently no fuel in the fuel rail, so I'll say 0, but have not tested it to verify.

 

let someone else turn the key to run to prime the pump and you hold the schrader valve open on the fuel line at the engine see if any fuel comes out. dangerous, have fire extinguisher around and be smart about it. if fuel comes out the pump is getting fuel to the engine at least. then you need pressure readings at priming, holding pressure, and running. As far as non-acdelco/delphi pumps in an s-series you are just asking for a bad time. It's the only vehicle I have ever had that anything other than OE fuel pump, cap, rotor will most likely leave you stranded at some point.

really only 4 things it could be, pump, filter, regulator, or spider assembly. in this case i would lean towards pump and as a backup say regulator.