GabeG

[backstory] My friend and I bought a '93 S13 with crank no start. It has a KA24DE; when we got our hands on it, it had stock ECU, some huge intake manifold with most of the sensors and vacuum lines missing, and some leaky fuel rail with unknown injectors. It seemed like it had a fueling issue, so we traced down that the fuel pump was out. We got the fuel pump working, but were unable to get it to start. --So we concluded that we'd be better off putting the stock equipment back on. We removed the aftermarket manifold and injectors and installed the stock stuff.

[Problem] So now that we have the intake and injectors back to stock, we try to start the engine, and it still won't start, and the cylinder #1 injector is leaking super bad from the (new) gasket between the injector and manifold, so we call it a night. I come back the next day to find the intake manifold and cylinders filled to the brim with fuel! Fuel is literally spilling out of the throttle body! I panic a bit, pump all the fuel out of the mani and cylinders, turn it over with the plugs out, change the oil, and then got it to run off of starter fluid! Thankfully, we didn't bend Rodney

[Question] So, here's what I'm thinking: How would the the engine and manifold fill with over half a gallon of fuel after trying to start the engine once? My thought is that, for some reason, the injectors are staying open. I hooked up my multi meter to one of the injector harnesses (which are aftermarket plugs intended for the aftermarket injectors that were poorly spliced by the PO) yesterday, and found that it kept a constant voltage until the battery is disconnected after opening the door without having the key in the ign. However, I usually leave disconnect the battery overnight, or else it will go flat.
SO, where do I go from here? What else would be worth checking?

Thanks!

S14rebuild

Pull the rail off the manifold, turn key on not cranking and see if fuel.is spraying out.

2 things....
1..u have an injector stuck open allowing fuel to continue to leak out into manifold and cylinder

2....there a short to ground on and injector driver(computer or harness) which is tirning the injector on a spraying gas nonstop to fill manifold/engine


Your testing diagnosis will point u in the right direction

GabeG

Good idea, will do. How could I tell if it's mechanical or electrical by pulling the rail off of the manifold?
Say it is electrical, what would be the best way to find the short?

NukeKS14

Pretty much nailed it here. Another cause could be the O-rings on the side feed injectors for the KA/SR like to leak and it'll cause fuel to leak around the injector, into the IM, into the cylinder. Pulling the fuel rail and priming the fuel system as described will show you if you've got a leak like this or anywhere else for that matter.

How did all of that fuel get into your engine? Well when you pressurized the fuel system and let it sit, it apparently leaked through the injector into the IM/cylinders. If you've got a bad leak through your o-ring/injector then it's just going to pump all of that fuel through with little/no resistance. Or if you have latched-in voltage holding the injector open, that'll cause it too.

*edit*
Read below for electrical diagnosis. The short of it is, remove the injector harness clips from the injectors. Does the injector still leak when you turn the key on and pressurize the fuel system? then it's mechanical. Does it ONLY leak with the injector harness connected? -> electrical
*/edit*

You're going to get constant 12V to the injector harness as long as the ignition key is on. That is normal. The way the ECU works is by grounding the control elements (injectors etc...) and completing the circuit that way. So if you checked positive from the injector clip to the engine block or another ground, all you were finding was that you're getting voltage to the clip.

You SHOULDN'T be getting voltage with the key out of the ignition. That isn't right. If that is the case I'd comb through the wiring harness and figure out what's been done. If you want to check for proper operation of the ECU and injection circuit, you should check between the two wires on the clip in VDC mode on your multimeter (Don't worry if you connect the leads backwards, you'll just get a negative reading) or use a small circuit tester like this;


Be sure to disconnect the ignition coil so you're not getting spark, but you should see flashes on the circuit tester or momentary blips on your multimeter if you have someone crank the motor while you watch. If you can read voltage between the 2 wires on the injector clip constantly at rest, then there is definitely something wrong. That would explain why the injector is being held open and leaking.

If you JUST get 12v at the clip to body-ground, then you have another gremlin to chase. Are there other things that are still getting power with the key removed? (idiot lights on dash, etc...) If so, it's possible you have a bad ignition relay latching in and not releasing. Could be the relay or ECU. I've seen both on an S13.

Before you go digging in the ECU to check for visual signs of damage, I'd try tapping on this relay after you remove the key. If that doesn't make power drop out, remove then reinstall it and see if the voltage returns. If it does NOT I'd replace the relay. Sticky relays are a real PITA to troubleshoot.

It's under the driver's side footwell and should be brown if you have power windows, blue if you do not.

If power does return after you remove/reinstall the ignition relay, could be the ECU... don't know. No idea what has been done with this car. Does it have a turbo-timer installed?

GabeG

That's all very good advice, and clearly worded as well! I'll go down your list next time I get a chance to work on the bucket!
As for other things done to the car, not sure about a turbo timer, definitely isn't boosted right now, but I get the sense that the PO intended to boost it based on the huge intake manifold and injectors. I know the ECU is stock (interior is gutted, easy to see things like that lol). I would think there would be some fuel pressure regular or other fuel controller installed with the aftermarket rail, but I haven't seen anything of the sort. Previous owners were, um, cough cough dumb-asses cough cough...
So to answer your question about the turbo timer, I'm aware of any aftermarket electrical controllers installed, or at least have yet to find them. Are there any typical locations that people usually put them?
Thanks again!

NukeKS14

If you remove the lower plastic cover underneath the steering column, you can see the ignition cylinder/wiring. Grab a pic of that and post it. Also the fuel rail. It's easy just by looking to tell if you're on the OEM fuel pressure regulator or something else entirely.