Hello i have been having this problem for a long time and i cant seem to be able to fix it.

i have a 1985 z28 305 V8 FI

My issue is

Starts Hard: once i start it it will re-start no problem but say i leave it for 15-30 min it starts hard again. but then sometimes when i first start it for the day it starts up so i cant tell if its cold or warm start problem.

It runs Pig Rich: sometimes so bad that after i start it i might as well just stick my nose into a 5 gallon gas can.

i have tried taking it in many times and they always find something but the problem doesn't get fixed. now every time i take it in it does run better but the reason i took it in never gets fixed

Whats been done:
Tune up with cap and rotor
O2 sensor

 

For starters any check engine codes? Also just for your info there are legal issues you can take up with a shop if youve brought it to them more than a certant number of times and the problem is not fixed. If you wish to go that route call up your local DMV and they can tell you all about it. I think its 3 times here in CT but your state is probably different.

 

nope there is no trouble codes what so ever. The mechanic is a close family friend and hes gonna relook at it on Monday but i want to see if i can fix it before. im impatient. i thought it might be the coolant temp sensor so i just went ahead and got one and im installing it tonight and ill see if that works but if anyone has an idea let me know

 

Did you check the injectors?
Also, fuel filter...

 

I replaced the fuel filter already. the coolant temperature sensor didnt do anything i wanna test the injectors but i dont know how do i have to take it to a shop to do that??? and i for sure know that it has nothing to do with being cold or hot because at 5'o clock in the morning its starts hard. and when the engine is warm it can also start hard.

 

If you have a fuel pressure gauge, hook it up to the test port on the fuel rail, Then turn the key on, The pump should prime for a few seconds, see if the pressure goes up. If it does, does it stay up once the pump shuts off or does it bleed off quickly. If you dont have a fuel pressure gauge..... get one they are cheap and youll need it to do any usefull diagnosing. Also as I see it's an 85 your dealing with, have you looked into the cold start injector? I suppose if it was leaking it could cause you to run pig rich. And as for the hard to start cold issue, You could have a flaky fuel pump relay this will cause you to have to crank the engine excessively before it will start but once it starts the pump will run fine.

 

Well i got some new information.

the hard starting is intermittent, it happened when the engine was hot at 3pm and when it was cold at 2am

the fuel pressure stays when i tested it.

I replaced the fuel relay but no change

i talked to someone and they said it might be the fuel pump what do you think

how would i test the cold start injector????

 

Testing of the injectors electrically requires an ohm meter.

Ohm the 2 prongs on each injector. Should read ~16.
Ohm the 2 prongs on the cold start injector. Should read ~4.

Those are the only tests you can perform on the injectors without disassembly.

Of course this is assuming that you have TPI which you didn't state.