I connected the fuel press. tester to the rail. when the key is turned to run position (without starting) fuel pump comes on, fuel press goes to about 60-62 psi, fuel pump goes off, then press. drops to 0 after about 4 to 5 seconds. If I turn switch to start quickly. Engine will crank once or twice and press. drops to 0 right away. It will sometimes start and runs good.
fuel pump? again
fuel filter? again
press regulator? where is it
help!!!!!!!!!!!
Do you have the fuel tester hooked the in the overgrown air valve on the fuel rail in the back of the engine? Or do you have the fuel line unhooked in the back and hooked to the pressure pump? You want the fuel pressure to be in that 60 lb range so if you are hooked into the pressure valve on the fuel rail allowing fuel to go through, then I am betting it is the fuel pressure regulator. To get to that, you have to take the throttle body off and take the plastic plenum that covers the injector packs. On the back of the mount where your six pack of injectors are sits the pressure regulator. If it is faulty then it is dumping fuel instead of holding the pressure like it should.
Get a Chilton or Clymer manual and it shows you in pretty good detail how to fix it. I've done it to my 98 S10 with the same engine.
If you unhooked the fuel line so you are losing pressure from the line back to the pump then I would say your pump is letting fuel back to the tank when it shuts off. My money is on the first possibility though.
Good luck
What kind of pump did you buy? If it is a cheap after market then my quess is it is the pump again. buy a good delphi pump next time. Unhook the vacum line from the regulator try your test again if it holds then the vac line is pulling fuel thru a bad diaphram in the regulator
IF THE VACUUM LINE IS PULLING FUEL THROUGH THE DIAPHRAM OF THE REGULATOR THEN YOUR MIXTURE WOULD BECOME RICH AND THE EVIDENCE WILL BE SHOWN AS BLACK SMOKE COMING OUT THE EXHAUST PIPE .
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