96z28_lt1

hey everyone finished putting the car back together went for first fire up and nothing sounds like starter is engaging but thats it put the throttle to the floor you get backfire sputters and engine goes to crank but never finishes turning over....

heres everything i've done to the car

le2 head
new cam
roller rockers
porten intake
bigger injectors
bigger throttle body
replaced opti plugs and wires
longtube headers
got rid of emissions evap smog egr air

from what i can tell car has fuel i smell it, unburnt fuel even at the exhaust tips you can smell it, not sure if its getting spark or if the battery is just not putting it out anymore because after an hour of trying to start the batt is already low on juice, anybody know the cause

EDIT: now that i think about it when i turn the key i hear a clunk from the engine bay but no longer hear the fuel pump kick on, car worked perfectly fine before i ripped it apart what to test for fuel pump?

Injuneer

To check the fuel pump, check fuel pressure. If no pressure, try powering the pump from the fuel pump prime connector under the hood near the PCM:

Courtesy of Shoebox:

http://shbox.com/1/fuel_pump_prime.jpg

The prime connetor bypasses the fuel pump permit signal from the PCM and the fuel pump relay.

Are you sure you put the cam dowel pin in the correct hole in the back of the Opti?

96z28_lt1

i'm positive on the cam dowel part has i double check it, i'm hoping the battery just doesn't have aenough juice i'm not gonna try anything right now because everytime i crank it and it back fires sounds like someones getting shot, just looking for info so tomorrow i can start my day with a good lead

96z28_lt1

i hooked up a cable from the positive on the battery and then plugged it into the fuel pump prime wire and walla no fuel pressure im gonna say that the pump is bad, now the question is with these mods should i get a higher performance fuel pump or should i just replace it with a stock one

Injuneer

First check to make sure the fuel pump harness connector over the rear axle is intact, and that when you apply 12V to the prime connector, you are seeing 12V at the rear harness connector.

Courtesy of Shoebox:

http://shbox.com/1/fuel_pump_wiring.jpg

96z28_lt1

alright will do, to check to see if its getting 12 volts is there any pins specificcally to put multimeter leads into?

gcouse7

You might get more imput from other members if you would check your spelling and use punctuation so we can understand what you are saying.

96z28_lt1

well i've decided its a bad fuel pump i sat in the car turned the key and can hear the fuel pump go to prime but its very faint a lot fainter then it use to be like slightest sound will keep me from hearing it

RamAir95TA

Don't rely on the sound it makes. Pick up a fuel pressure test gauge. It's an invaluable tool for any LT1 owner.

96z28_lt1

i will do that im just taking a logical guess i mean if its pumping fuel but not enough to start it that would cause backfires would it not especially with the throttle at wide open throttle
?

Injuneer

Do you mean a "backfire" through the intake manifold (takes fuel, air, spark and an open intake valve) or a backfire out the exhaust? It's not going to backfire unless its getting fuel.

96z28_lt1

it was a backfire out of the exhaust, but only every so often rarley happens the rest is like a stumble and the tach goes up to like 300rpm and it just keeps trying to start, only reason i think its fuel is because i can barely hear the fuel pump. i picked up a gauge from autozone and am going to test the fuel pressure how much psi should i have with just ke turned to on?

96z28_lt1

update: hooked up fuel pressure gauge turn key and there you go no fuel pressure safe to assume now that the fuel pump is bad?

Injuneer

Sometimes the pin in the connector for the test gauge doesn't depress the core valve in the Schrader connector. That will result in no pressure reading. You could pull the valve core out of the Schrader fitting before attaching the test gauge to be sure.

You should see at least 40psi when the pump primes.

96z28_lt1

well i am getting fuel now, its leaking out of the header but there is no spark, i pulled a plug it looks good like it hasn't even been fired on, no spark coming to spark plug wires checked that also i checked the plug on the top of the coil i guess its the coil module and the opti is sending signal to it check the coil wire its getting spark leads me to believe the problem is within the cap and rotor is it possible for the rotor to come off even though the car hasn't even been ran, i didn't know to loc tite the rotor which was my bad but i took it right out of box and installed.