I have a 96 z28 lt1 auto. So it started having a problem starting. It would just take a long time to start. Once it starts though it runs great and smooth. I changed the plugs gapped at .050, had the injectors cleaned, replaced the fuel filter and coil(optispark unit), and changed a coolant temp sensor. Now it still has the long cranking. Anyone have any ideas? Its not throwing an codes. Im thinking I may need to find someone with a nigher end scanner and monitor the engine?

 

have u tried this;
turn the key on and let the fuel pump prime (the wineing noise the u hear when u turn the key on) and shut off. turn key off and back on and let the pump prime again. do this 4 or so times and then try to start it.
if it starts right up u are losing pressure somewhere. fuel pump or leaky fuel line is about all thats left that u havnt replaced.

 

Try looking into the Ignition Control Module which can be known for hard starts. First try the fuel pump. Test the pressure at the schrader valve(looks like a tire valve with a cap) at the back of the intake with a fuel pressure regulator(should be 41-47 psi). Make sure you this with the ignition on the ON position.

 

craby is right! it sounds like a fuel issue. you could see if its fuel for sure if you spray a little starter fluid into the throttle body and see if it fires right up ( but be carful not to set your motor on fire with the starter fluid. make sure to spray at a good distance)

 

So I went out and tried to start. Still hard cranking. Then I turned the key on 4 times. Car fired right up! Im going to get a fuel pressure gauage tomarrow. If its not putting out the pressure it should be is it safe to say its the fuel pump? Ive already followed the lines closely and dont see nor smell any fuel leaking.

Also when you turn the key off. What is making the vacumm sound?

 

dont know, i dont remember any sucking noise. ill have to go start mine. lol.so when u had the injectors cleaned did they test them. a leaky injector will do it to and cleaning might not have fixed that. if not leaking out lines fuel can go either way, back thew a bad pump into the tank or leak through a injector into a cylinder. only things i can think of to test injectors is try priming the pump a few times and pull the plugs and look for gas or pull the fuel rails lose (holds the injectors in) and prime, should see fuel coming out of any leakers. fyi opti is the distributor.

 

and yes if the pressure is down its probly the pump could be the pressure regulator to, i think. lol. check to see if the pressure drops after setting.

 

To my knowledge to pressure should be the same at idle throughout the rpm range correct? According to Dr.Injector in Renton non of the injectors are bad

 

This is from another thread:

"1) Connect a Fuel Injection pressure gauge (available from most part stores) to the test port on the FI rail (similiar to a tire valve). Be carful as fuel under pressure may spray out.

2) With the key ON & engine OFF (cycle the key ON-OFF several times as pump only runs for 2 seconds) the pressure should be 41-47 PSI. (If NOT: weak pump, dead pump, or no power to pump)

3) Turn key OFF, pressure should NOT drop more than 1-2 PSI and then hold steady. (If NOT: fuel line leak, injector leak, regulator leak, fuel pump check ball leaking)

4) Let engine idle, pressure should drop 3-10 PSI from the reading in step 2. ( If NOT: bad pressure regulator, vacuum leak to pressure regulator.

5) WOT (car accelerating at full throttle, pressure should hold @ 41-47 PSI. Good to have two people, one to drive and one to watch gauge (If NOT: dirty fuel filter, weak pump, bad pressure regulator)"

 

You guys have/are extremely helpful. So tonight I put a fuel pressure gauage on it. I cycles the key 10 times. I never got more than 37psi rail pressure. It did drop 2 psi but held. I then started the car and at idle it was at about 38psi but never dropped? At wot it nver reached more than 39psi.

So im convinced my pump is weak. My question is how come my pressure never dropped at idle? Should I still be concerned about the fuel pressure regulator?

Again guys thanks. You have been very helpful so far