derSchwamm

iTrader: (1)

I just tried starting a fresh rebuild and it looks like my rear injector is stuck open. After trying to start it for a while I eventually pulled the leading plugs and gas poured out the rear plug hole. It had filled up so much of the rear rotor that it gushed out. I even unplugged the injectors at the front coil and turned the engine over and it kept spraying out the back without decreasing which makes me think it stuck open when I tried to start it the first time. (Eventually trying to clear it out caused a fire but that's a separate thread...)

So, what can I do to fix the injector? Do I just need a new one? These were sent out for cleaning and testing before I installed them and supposedly they were good

GSLSEforme

Haven’t read your other thread about the fire but i’d want to be sure the signal to the injector was not corrupted from a wiring issue or ecu fault causing it to dump fuel.
Personally haven’t seen many defective SE injectors fail in this manner, particularly after having just been serviced.

Maxwedge

iTrader: (1)

!!!!!!!!!!😳!!!!!!!!!!

derSchwamm

iTrader: (1)

What effect if any would having the air flow meter unplugged have? I just realized it was still unplugged while I was doing this. The wiring connectors on the injectors are pretty torn up too. Is it possible that an injector would be held open due to a bad connector?

j9fd3s

iTrader: (3)

if the connector shorted, it could lock the injector open, although it could also just be clogged with crud and be stuck open on its own, i've seen that a couple times (usually they are stuck shut)

AFM unplugged didn't help, but if the injector is stuck, it was stuck...

LongDuck

Injectors only fire when you apply a current to them. The ECU determines the 12v current at a specific duration of time, which is how fuel flow is controlled. U less your wiring harness was shorted in such a way as to run 12v to ONLY the rear injector (*very unlikely), its a mechanical sticking situation internal to the injector. If they were cleaned recently you need to contact that shop and have them look at them both to be retested.

You can buy Borg-Warner Injector pigtails at your local parts store. They are common parts, and the pigtail ends can be spliced into your injection harness easily enough. This ensures you have good connectivity to the injectors going forward. Where these typically fail is someone muscling them off with a screwdriver, which breaks the plastic on the connector which holds a metal bail securing the connector to the injector. Once broken, the connector slips on and off easily and doesn't make good contact. Most "running-on-one-rotor" complaints on the -SE are caused by this. The replacements pigtails were $7/ea about 10yrs ago. Cheap insurance.

Get the injectors retested. I'll bet one of them is stuck open. The Air Flow Meter is REQUIRED fpr the car to start, otherwise, the ECU has no idea how much fuel to send because it senses zero incoming air, so the injectors will not fire without a AFM signal. In fact, your fuel pump won't even be energized without it.

derSchwamm

iTrader: (1)

Thanks, I figured. Is there anything I should do to ensure that's the issue before I mail them off again? My connectors are in bad shape and I already ordered new pigtails, but it sounds to me like you're saying that wouldn't cause this flooding.

This can't be true. I had it unplugged the whole time I was trying to start the car (by accident) and the fuel pump kicked on without problems, and the car sounded like it wanted to start the first time. I was definitely getting spark too... because of the fire it started.

j9fd3s

iTrader: (3)

the fuel pump is turned on by either the ECU seeing Rpm, or the key in the start position. there is a switch in the AFM that turns the pump on with air flow, but the key might bypass that? (i'd have to look at the diagram)

the ignition will work with power, AFM has nothing to do with it

GSLSEforme

Some clarifications regarding SE fuel system.
Injectors are fired by a ground signal from ecu. They have 12 volts available at one of the terminals whenever key is in run position.

Ecu will not fire them til it sees an rpm signal from trailing ignition coil(black wire on trailing coil negative primary terminal).

Fuel pump will not run in key on position until contacts close from incoming air moving flap door in air flow meter as engine is cranked over.

The only other way for fuel pump to run in key on position(without engine running)is for test connector to be jumped or wiring to it being compromised.

OP,your car should never have even tried to fire in scenario you describe.
Air flow meter unplugged,there would be no fuel available as fuel pump would not run.
The fact it did fire(almost started?)and began to flood,indicates corrupted wiring,ecu fault or some other anomaly that completed injector(s) circuit.
Was it only the rear rotor injector that caused the flooding,has this been proven?

Regarding the theory,the injector came back from a(reputable) cleaning service with the pintle in stuck open position,this is debatable though imo highly unlikely but not impossible.
I believe on returning injector for testing,no faults will be found.

Imo a wiring fault caused the injector(s)”on”condition and the source of this unintended ground needs to be found. It could be as simple as a pinched wire. The condition of the wire harness post fire may complicate finding evidence but should be able to be found.
Without now 1st verifying integrity of each wire in fuel/ignition system it would be foolish to power up and attempt starting this car.

derSchwamm

iTrader: (1)

Thanks for the detailed responses., it's very appreciated! I'll give more info around what all I did and maybe you can point me in the right direction.

Context:
1) Wiring harness was previously working without issues before I started this restoration BUT the injector connectors are definitely damaged and will be replaced
2) AFM was unplugged throughout this entire process, by accident.

What I did:
- Turned key to 'on' a couple times, then cranked the car. This first time I heard a couple small 'blips' that sounded like it was starting to fire, but these were minimal.
- Repeatedly tried cranking after taking several minute pauses to let the starter cool off and the battery charge up
- Eventually pulled the plugs to check for issues. Plugs were covered in assembly lube (I probably used too much in the rebuild) so I installed a fresh used set
- Cranked a couple times again. No change, still didn't start
- Pulled plugs again. This time they were clearly soaked with fuel
- Unplugged blue connector on the front ignition coil to kill injectors, then cranked the engine with lower plugs removed. Fuel vapor sprayed out
- After repeated cranking like this, I noticed the rags I used to soak up the fuel by the rear housing were still getting soaked, despite the injectors being disabled. This made me think that injector was stuck open
- I finally just put the plugs back and reconnected the plug on the coil and cranked it again. No change, engine just turned over.
- Pulled plugs one last time and fuel actually started running out the rear lower plug hole. The front housing was not doing this although the plugs were wet all around
- Cranked the engine with the front coil connector undone one last time before giving up for the night just to clear the excess fuel out of the rear housing. This is where I did a dumb thing and started a fire... because it was spraying fuel out near where the spark plug wires were dangling.

Maybe these details will shed some light on what happened?

One question: if the fuel pump can't get power in the 'on' position, can it get power in the 'start' position, such as in repeated cranking scenarios like I was doing? I'd still like to know for sure why I got fuel

GSLSEforme

Answer to your question,no.
In a properly wired,functional component SE,the only way the fuel pump runs is by air flow meter connected mechanically/electrically and engine cranking,pulling air thru air flow meter,closing fuel pump contacts within.

OR,fuel system test connector is jumped or that piece of harness is compromised/modified.
IS that connector present and unmolested?

Even though something is wrong with fuel feed circuit allowing presence of pressurized fuel in system...the injector(s)had to fire to introduce the fuel...you have at least two problems.
I believe both to be wiring related.
Process of elimination...
1st thing to check-status of fuel system test connector
2nd-test contacts in air flow meter for fuel pump. Should be no continuity with flap in closed position
3rd,need to verify all fuel/ignition wiring integrity end to end for continuity and to ground.
You will find problems here most likely.

GSLSEforme

What is present condition of fuel system?
If not 100% sure,pull fuel filter and drain onto paper towels and bang filter to dislodge possible debris.

derSchwamm

iTrader: (1)

Thanks, now that you mention it this car once had a fuel pump cutoff switch inside. It never worked for me, but who knows what wiring is messed up because of that. I’ll check all the wiring for sure, I just need to pull the manifold and injectors and get started.

Because the car had been sitting for a while I also drained the gas tank, replaced the fuel filter, and added 5 gallons of fresh gas

GSLSEforme

Pull the filter and do as recommended. Need to rule out debris in fuel system.

GSLSEforme

These are the Throttle Position Sensor and fuel system test connectors. TPS connector is 3 terminal green connector and the other is a two terminal with a black boot. Are they both present ?

derSchwamm

iTrader: (1)

Yep they are there. I still have the factory GSLSE wiring harness in its entirety

derSchwamm

iTrader: (1)

I pulled the manifold and started troubleshooting. With the key in the on position, I’m getting 12v at each injector connector, solid. Same with the AFM plugged in or unplugged. I tested with a test light. That seems wrong? I’d only expect a pulse when cranking

I know I need to check the fuel system for crud but it’ll have to wait, i can’t do it in my garage without stinking up the house

Edit: I also checked when the fuel pump kicked on with and without a jumper in the fuel system diag port, and it kicks on when expected. Without the jumper I hear nothing from the backend regardless of if the AFM is plugged in, and with the jumper I hear it

Edit 2: rereading this, i see that the 12v is expected because they are switched to ground. So I could have a short in the ground side causing the rear injector to be held open. I’ll test that next

GSLSEforme

12 volt injector feed is supposed to be there with key on,has nothing to do with air flow meter. The injectors are grounded thru ecu to fire them.This is common technology even on modern cars. From here on out for checking for injector signal you need to use a logic probe or noid lite to prevent damage to drivers in the ecu with a test light.
Again,the voltage is not pulsed to fire the injector,the ground is turned on/off by ecu with input from various sensors and trailing ignition rpm signal. You need to familiarize yourself with how the different components work together for the car to run.

GSLSEforme

GSLSEforme

What you have found so far regarding fuel system does not add up to you having fuel pressure at the rail without air flow meter being hooked up. Investigating wiring for added in fuel shutoff would be appropriate at this point.

derSchwamm

iTrader: (1)

I agree, and it’s making me rethink about what I did when i tried to start it the other day. I know I had fuel pressure because I found a leak at a loose soft line early in the night, but this could have been after the first time I tried to start it. In which case the fuel pump is kicking on correctly like all my testing tonight has shown. With the fire and all it was a long night, and I think I forgot about that and went down a rabbit hole thinking the pump was on when it shouldn’t have been.

Also, the switch in the dash doesn’t seem to go anywhere. Wires are disconnected. I think a previous owner already removed this system.

How exactly will a test light damage the ECM when this noid light won’t? All I did was check if the injector connectors were grounded with the key in the on position by putting a test light between the two pins. Neither injector was grounded which would be expected. Doesn’t look like there’s a short in the wiring but I’ll check continuity in these tomorrow to be sure.

The last thing I did tonight was unplug the injectors and force the fuel pump to run via the fuel test port then turned the ignition to on for 10 or 15 seconds. I turned the engine a few times by hand and pulled the lower plugs and didn’t see much gas. I definitely didn’t see a lot more gas in the rear housing, so I think I can say the rear injector isn’t physically stuck open. At least not today.

Based on all this, I don’t think I’ve found a problem with the fuel system yet. I’ll keep looking over the wiring diagram tonight and forum posts tonight

I do have several years of experience working on this car and I’m not ignorant of how it works, but it’s been two years since it ran and I’ve done a lot more work on the FD since. It’s hard to keep things straight like how the two cars behave with the ignition switch on. I’ve also never had a problem with the fuel system specifically of the SE so it’s taking some reading to learn the details

LongDuck

As this isn't a true -SE intake, per your other thread, you may be dealing with wiring issues that are causing this problem. Is this your current intake setup?

https://cimg5.ibsrv.net/gimg/www.rx7...21ce0e1886.jpg

Thanks to GSLSE4ME for clarifying how the factory injectors are switched. I learned a few things,

GSLSEforme

Impedance of 12 volt test light is too high,mood lite is proper tool.

derSchwamm

iTrader: (1)

Yep you found my intake from another thread. This setup is temporary to start the car, I’ve ordered the parts to do something custom between the AFM and throttle body so I have an air filter etc again. I know it looks a lot different than the SE intake but I’m using all the original SE sensors and wiring including the TPS which I made a custom bracket for. I also installed the SE BAC and ACV.

Im working on a full S5 swap including wiring and the s5 ECM but I thought it would be quicker to run it like this and break the engine in for a while

derSchwamm

iTrader: (1)

Got it, I guess I’m lucky I haven’t damaged any other cars this way. I had no idea

Unfortunately with this lockdown I can’t just run out and buy or rent a Noid light set, so that testing will have to wait a bit. I’ll see if I can order one online