lt1 wont start

[toolman162002]

ok update on the lt1 to refresh i did a cam install cc306 i got the car to fire but acted like it was a missfire so i took my harmonic balancer off and checked out my opti and it seemed to be fine. i took it up to the parts store and switched it out with another one (under warranty) installed it and wentto start it and it wouldnt fire. So i took startin fluid and sprayed it into the throttle body and she fired ran smothly but wouldnt stay runin. only time it ran is when i when i spray startin fluid into it. any ideas? new coil, icm, plugs, wires, opti its a 94 z28 lt1

[85z28kid]

Sounds like its a fuel issue. It's getting spark if it's running with the starting fluid.

Can you hear the fuel pump come on?

Did check all your connections??

[toolman162002]

has a new fuel pump gettin 43 psi thats before i swithchd the opti out. all the connections seem to be hooked up

[meissen]

Yeah sounds like it's definitely not getting fuel if it only runs with the starting fluid - it's not a spark issue. Are there any lights on on the dash? Security light? Service Engine light?

[toolman162002]

i have bypassed the vats system. and the check engine light is its been on since i owned the car. ill check the fuel pressure again tom

[meissen]

Do you know why the engine light is on? The problem with leaving it on is when something new occurs it could be telling you why the car doesn't want to start but all you see on the gauge cluster is the same light still on even though new codes could be popping up.

[hoogiesngrinderz]

You likely have a bad/dirty optical sensor in you OPTI.

[meissen]

You likely have a bad/dirty optical sensor in you OPTI.

If it runs OK with starting fluid I would not think it's spark related, don't you agree? If it was a bad/dirty optical sensor then the starting fluid theoretically shouldn't make a difference.

[hoogiesngrinderz]

Well, lets break it down...I don't want to yell OPTI when it isn't the case. I assume one would check the fuses and go from there

1. Check the fuses. If good - goto 2. If not - goto 1a.
1a. Duh. If the fuse blows right away then you need to trace for a shorted wire.
2. Check power to injectors by grounding the negative of the multimeter and putting the positive to one pin on the connector. If no power, try the other pin. If one of the pins has 12 volts - goto 3. If neither have 12v - goto 2a.
2a. You need to trace for a broken wire.
3. You can check with a noid light, but you're pretty much left with three things - bad injector driver(s) in the ECM, not getting a low resolution track from the opti, or a broken/shorted wire from the opti. (unless you forgot to plug a connector back in )

It uses multiple optical sensors. Probably not getting the low resolution track to the ECM, causing the injectors not to fire.

[meissen]

But again, spraying starting fluid in which allows it to run seems to suggest the spark is fine, no?

[hoogiesngrinderz]

Spark is done by the rotor that is in the opti. If the coil is charged and the motor is cranked, it will spark. High resolution track is for timing purposes, but without the low resolution the injectors won't fire and the pump won't run after the initial prime.

[meissen]

but without the low resolution the injectors won't fire and the pump won't run after the initial prime.

Thanks - that's the part I was overlooking.

[sman]

VATS does fuel right?

Has it ever ran since you bypassed the VATS?

[killa89trans]

if it runs off starter fluid = fuel related issue, whether bad power ground to pump/resriction of some sort with fuel.

[hoogiesngrinderz]

I guess I assumed he did VATS before the cam swap, but that is a good question.

Pump is working, hes said there is pressure. I wonder if the pump comes on while it cranks...if it does (and he has power to the injectors) that would narrow it down to injector drivers I guess This is also assuming he doesn't have the hot wire kit