Car won't start

[Fii]

We finally have put together the red car and tried to start it today, but unsuccessfully. 6 months ago the car was starting fine, but instantly died, we found out that the problem was with the fuel line at the tank - it was leaking badly, so when the car started it ran out of fuel. Now it is finally fixed and we tried again.

The sympthoms are the following:
It is cranking but nothing happens, nothing at all.
The spark is definately there. And fuel is getting to the rail. I could not figure an easy way to check whether the fuel is actually being injected. When I removed spark plug it was completely dry. So I guess the fuel is not getting there.

I took my voltmeter, removed one injector plug and checked the voltage against ground with ignition on. It showed 12V on both leads. Is that right? Shouldn't it be 12V to one lead and nothing to other? Or is it because the other injectors were connected and it got voltage through them?

Where could be the problem? Wiring? ECU?

[Ivan141]

Okay, the injectors work like this: They get a direct permanent 12V, the ECU is connected in the groundpath of the injectors and closes the path to ground when it wants to fire the injectors. So if your not turning the engine and the ECU is not trying to fire I would expect the injectors to get 12V on both leads (no voltage difference, no injectors firing).

How have you checked your fuel pressure? Easiest way I think would be to disconnect the cold start injector fuelline and run the starter for a short bit. If the fuelpump is working OK you should get an expensive fountain (like JesseP explained it to me ).
You can also try to listen or feel if the injectors are firing.. I believe some use a stethoscope or put a screwdriver against them to feel for their clicking..

DONT FORGET TO CHECK YOUR FUSES! (especially the one called EFI)

[Fii]

Ivan141 Wrote:Okay, the injectors work like this: They get a direct permanent 12V, the ECU is connected in the groundpath of the injectors and closes the path to ground when it wants to fire the injectors. So if your not turning the engine and the ECU is not trying to fire I would expect the injectors to get 12V on both leads (no voltage difference, no injectors firing).

It somehow seems strange that ECU would output 12V on the injector ground pin all the time and switch to ground when necessary. But of course, if it does so, there is no harm. Just seems strange to bother to output 12V instead of just applying the ground to the pin.

Ivan141 Wrote:How have you checked your fuel pressure? Easiest way I think would be to disconnect the cold start injector fuelline and run the starter for a short bit. If the fuelpump is working OK you should get an expensive fountain (like JesseP explained it to me ).
You can also try to listen or feel if the injectors are firing.. I believe some use a stethoscope or put a screwdriver against them to feel for their clicking..

DONT FORGET TO CHECK YOUR FUSES! (especially the one called EFI)

Yes, I got an expensive fountain, when I unbolted fuel line from the rail.
EFI fuse is fine, and other fuses seemed to be ok as well.
I could not feel injectors working with my fingers. I will try with a screwdriver.

[Ivan141]

Fii, the ECU doesnt put out 12V at all... I think the injectors have a coil in them, which causes an inductive field that opens a switch when current flows through it. A coil is basically a fancy short circuit, so it's logical that you would read 12V at both ends of it when one side is not connected (or floating as it is called).

I dont know if there's a simple way of checking if the ECU is actually pulling the signal low when your trying to start, but that would offcourse be the best way to see if they are firing. Have you tried to put the ECU in diagnosis mode yet? Might give you some helpful information.

I think it's most likely just a minor electrical problem, hope you fnd it soon. Also make sure you check that all the grounding points of the wiring loom are correctly connected, it can cause weird problems sometimes..

[Fii]

Thanks Ivan!

I will disconnect all the injectors and try measuring again.
And then I could try to remove the rail completely and see whether the fuel is coming out of the injectors when cranking.

If there is fuel and spark, I believe the engine should run. Maybe I should try to start it by towing with another car?

[jnk]

Fii Wrote:Thanks Ivan!

I will disconnect all the injectors and try measuring again.
And then I could try to remove the rail completely and see whether the fuel is coming out of the injectors when cranking.

If there is fuel and spark, I believe the engine should run. Maybe I should try to start it by towing with another car?

its too messy to remove all the rail. maybe its better to check injectors impedance. i think they will be ok, i dont think, that all injectors fucked up at the same time.
and, if impedance is ok, try to check if everything is happening with check light on ECU outputs.
test bulb is too slow, u must have some LED+resistor at home ?

[jnk]

btw, my redtop 4age after inactivity periods starts up only after very LOOOONG cranking. especially when battery was disconnected in that period.

[Ivan141]

After giving it a second thought, there might be a problem with your wiring or ECU anyway...You measured the voltage with the connector loose so one would expect the end that goes to the ECU to read zero volts. How much of the wiring did you have to put together exactly?

Anyhow, run the ECU in diagnosis mode first, see what comes out.

[Fii]

Ivan141 Wrote:After giving it a second thought, there might be a problem with your wiring or ECU anyway...You measured the voltage with the connector loose so one would expect the end that goes to the ECU to read zero volts. How much of the wiring did you have to put together exactly?

Anyhow, run the ECU in diagnosis mode first, see what comes out.

Yes, the connector was loose. But since ECU fires injectors in batches it could be that I was measuring the voltage through the second injector in that batch. I think it was not a valid test, I will have to recheck it.

I did not mess with any engine related wiring at all. Since summer, I just soldered new connectors for headlamps and turn signals.

[Ivan141]

Make sure your battery is in good condition...damn things wont start unless the battery is strong. I've had this problem once and it wouldnt start even with some starter cables hooked up to my moms car.
Banpei had the same thing...dead battery, no start.