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Adam

Interesting Injector issue 86' GTE

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Hi all, 

New joiner here, shamefully jumping straight in for some tech help :unsure:

I have an 86' Manta GTE, which has been sat for 7 years, now it's time to get her running again!

After replacing the dead fuel pump I have managed to get her firing and running, but only for a few seconds then it dies.

I have confirmed that there is fuel in the rail, the 5th injector opens on startup (hense the running at all, once it's used that it cuts out) but the main injectors are not opening.

 

Checks so far.

There is fuel in the rail

There is a decent spark (it runs beautifully in fact for a brief moment) 

The injectors do NOT inject, but....

The injectors do open when bench tested.

I do have a +12v supply to the injectors when the engine is cranked right up until it cuts out

I have ground to the injectors when the ignition is off, but this goes as it's cranked and doesn't come back until the engine cuts out.

If I diconnect the hall sensor from the the system it will not fire at all.

The coil has all the correct feeds.

So, all seems to be working correctly, except for the ground switching for the injectors. But that's where I'm stuck, I can figure out why? I've checked and cleaned the ground for the ecu on the back of the inlet manifold, no change, but more interestingly, I tried it with it disconnected and it made no difference <_<

 

Any advice greatly received and thanks in advance.

Adam

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Check the fuel pump relay on the drivers side inner wing is ok. This is a common fault. 

You can by pass the relay to test the theory.

 

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Thanks for the swift reply.

Now they where my first thoughts, I have linked pin 30, 87, and 87a together to no avail.

Also from what I can tell the relay controls the +12v supply to the injectors? This is present while the engine is cranking and running up to the point it cuts out.

Does it also control the ground side of the circuit? 

Just also noticed that with all 4 injectors disconnected you loose the +12v feed altogether, but it returns when one injector is connected.

Thanks

Adam

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If you have a can of easy start you can perform a very simple test that will prove the ignition is fine and the fuel supply is the issue.

As you're starting the car squirt the easy start into the inlet and if it continues to run while you're using the easy start then you definitely know you have a fuel issue.

Other things to check are the fuel lines, do you have them the correct way around? Do you actually have the correct fuel pressure etc...

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I have just connected it to a bluepoint jetronic test set, including replacing the pump relay with a switchable relay.

All looks good and performs much the same with the switchable relay In. And all signals are correct, with the exception  of the injector signal. It does nothing :blink:

Even with easy start it cuts out, it's like it's being stopped rather than running dry, like the ecu is saying no rather than being forced to stop.

I'm now thinking hall sensor, however my only reservation on this is that with the hall sensor disconnected it won't run at all, the only sensor that effects it in any way, so it suggests it's working!

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Hi Adam, you've probably already done this but it might be worth checking/cleaning the "air flow sensor wiring plug" as a poor connection there on the "pins" could possibly create a "fire up, cutting out" fault. Good luck.

 

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The airflow meter shouldn't stop the injection running at idle. Interesting that the ignition shuts down as well as the fuel system 

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It's worth noting that the dissy is not controlled by the ecu. The hall sensor sends a feed to the injection relay to keep it latched. So the fuel pump stops if the engine stops.

You should not loose spark and the engine should run off easy start even with the ecu unplugged.

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Snowy your quite right there, I've had a little play with my gte and by disconnecting or loosely connecting the air flow wiring, it seems to give a non start situation.

Adam have you got a "noid/led" tester to plug into the injector wiring at the injector? This could tell if you are getting an ecu switched earth. It should pulse/flash on cranking and engine running.

I have disconnected one injector on mine and with the fuel pump relay bridged pin 30 to 87b this gives a 12v reading on both pins (ignition off or on, same reading) which sounds strange as one pin comes from the ralay providing the 12v the other one goes to the ecu, so you wouldn't think I would see a 12v on both, but as the other 3 injectors are still connected i would have power going through those injectors so might see a ghost voltage as they all share the same path to the ecu.

Now with all injectors connected and engine running I still get a 12v reading at both pins (fuel pump relay connected)

So Adam, have you tried/checked 

if you crank your one over and when it starts does it keep running if you don't let go of the key and keep cranking?

if it cuts out even when you have kept cranking is the spark still present at the spark plug (HT tester required)

if the spark is there all the time even when it has cut out and kept cranking, then I would think all is good there

if yours stays running when kept cranking and cuts out when you let go of the key then something is being lost from the "ignition on" position

If all is good with the HT spark and you have 12v is at the injectors and the noid/led light flashes ok then the ecu would seem to be receiving the correct signal from the Hall effect/ignition module.

let us know how you get on.

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To answer a few points above, well one in particular really, I do have a noid tester, and no,it doesn't flash :(

Just like you I was thrown by the 12v at both pins on the injectors then realised why! 

I think the issue is definitely with the lack of signal to the injectors, but in yet to figure out why :(

 

Cheers

 

Adam

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Hi Adam, well as far I know the Hall effect/ ignition module triggers off the ignition coil for the spark while also sending a signal over to the fuel pump relay to operate the fuel pump which also gives the injectors a 12v feed. The ecu must also be able receive or see this signal sent out by the Hall effect/ ignition module for it to activate (switch the earth) for the injectors as this is the reference point of injection timing.

So connections to and from the ecu and ignition module would be my next thoughts to check. I will need to check with the wiring diagram as to what colour wire to concentrate on.

sorry if I haven't been much help here,....but I hope you can crack this soon.

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The ecu does not need to see the hall effect sensor. It just latches the fuel injection relay. This keeps the injectors powered. When I get on my PC, not my phone, I will post up the write up I did on this.

I know you're saying the injectors aren't firing. But you also say you've no spark. 

I'd fix one before the other. Having a spark is nothing to do with the injection. System or ecu.

 

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So you could have a faulty hall sensor/ wiring or fuel pump relay. As these would all explain It running fine for a few seconds then the latching part that Snowy mentions unlocks and everything stops. So you need to know why it unlocks, either the hall sensor signal stops or the relay releases when it shouldn't

First thing i'd do is get another proper fuel pump relay and try that as it is by far the easiest test and in my experience iffy ones of these can give all sorts of random errors with the engine (plus as you own a Manta its worth carrying a spare in the door pocket incase of issues in the future). Next would be to change the small wiring loom between the dizzy and the coil/coilpack in case there is a wiring fault in it, like a corroded/damaged wire that works for a few seconds then overheats and kills the signal. Finally swap the dizzy for another (ideally known good one)

I'd also consider swapping out a few of the other components with known good spares just to check. Like the ECU and ignition pack, as either can have odd issues that cause weird behavior on the CIH engines and are very easy to swap to check/eliminate from the list of possible (however unlikely) causes. Again worth having good spares of these for future.

You will find a lot of people on here have spares of the common problem electronics and carry them around in the car, that way if it plays up simply swap out each item in turn and see if it starts working again. When it does get another spare of that item and continue driving :thumbup

Of course the other common issue is the injection wiring loom itself, these run very close to the exhaust and can be affected by the heat so the go brittle internally and again cause all sorts of issues. Its probably the least likely and also the hardest to check/change so i would certainly leave it to last. But i thought i'd mention it as you may not know its a common problem area.

 

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I do have spark, the engine runs, its only stops sparking when the engine stops turning :)

My only reservation on the 'latching' failing to hold being the issue is I don't have injectors even when it's running, as you they are have failed to inject a single morsel of fuel into the engine, I've have then out, connected up and tried,they simply don't open when connected to the engine.

Yet do open on an external source.

My next step is to eliminate the chance of wiring faults by building an additional loom to take power to the injectors, and ground from them, plug the power direct and use the OE ground, and test. Then the OE power and replace the ground signal to the ECU pin 12 and Test, this will eliminate wiring issues, and I have all of the bits to try that in the workshop, parts to start swapping I don't have, so will need the nod from the owner before I start spending his cash :)

Thanks for your help so far guys, I do appreciate it :)

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7 hours ago, Adam said:

I do have spark, the engine runs, its only stops sparking when the engine stops turning :)

My only reservation on the 'latching' failing to hold being the issue is I don't have injectors even when it's running, as you they are have failed to inject a single morsel of fuel into the engine, I've have then out, connected up and tried,they simply don't open when connected to the engine.

Yet do open on an external source.

My next step is to eliminate the chance of wiring faults by building an additional loom to take power to the injectors, and ground from them, plug the power direct and use the OE ground, and test. Then the OE power and replace the ground signal to the ECU pin 12 and Test, this will eliminate wiring issues, and I have all of the bits to try that in the workshop, parts to start swapping I don't have, so will need the nod from the owner before I start spending his cash :)

Thanks for your help so far guys, I do appreciate it :)

If the car doesn't continue to try and run when you're squirting easy start into the inlet then you must be loosing your spark.

If the ignition system, and engine, are fine then you should have no issues getting the engine to tick over, badly, but tick over all the same on easy start.

It's well worth doing this as you may have multiple issues, and by doing this you completely eliminate the fuel system and ecu, loom.

Just take the black hose off between the air flow meter and inlet. 

Give it a go, takes five minutes.

Edited by Snowy

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Well I agree the ignition module/Hall effect sends a signal over to the fuel pump relay for it to latch, which in turn provides a 12v feed to fuel pump via pin 87 and and a 12v feed to to injectors via pin 87b.

so now the injectors have a 12v feed, we now need an "earth return" to complete the circuit for the injectors. This is provided through the ecu pin which I believe is "switched" on and off by the ecu, thus creating a pulsed injector.

the earth circuit for the injector is "open" until the ecu is "aware" of "something going on". That "something" has to be a signal of some kind from the ignition module/Hall effect side of things, otherwise how does it know, when to pulse the injectors at required intervals? 

Anyway  that's my understanding of our gte injection system, I might be wrong but surely the ecu must need to have a "reference" signal of some kind to work by.

Adam have you checked the ecu has power to it, I think it's main 12v for the injection loom comes from the main starter motor solenoid nut where the battery live connects to it. Not sure if power to the ecu from there, goes through a fuse.

once again good luck.

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Hi Adam, just had a look at a wiring diagram and can't see a and ignition switched live feed to the ecu, but I do see the same wire (green) that goes to the fuel pump relay for it to latch also goes to pin 1 on the ecu, so I think that's what the ecu has to see for it to pulse the injector earth circuit pin 12 at ecu.

I think the 12v supply from the main nut of the starter motor just goes to the pin 30 of the fuel pump relay.

 

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You're making one of the most simple fuel injection systems sound more complicated than it is.

You have a stand alone loom that has a live connection, and earth and a four pin plug.

The issue is very simple. You either have a wiring fault, bell out the injection loom, or component failure. Test and replace.

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IIRC the 3 pin connector on the dizzy used to have problems with the wires breaking inside the housing, this was on all the vauxhall astras, cavvys etc. as well so a common(ish) fault. Worth a check.

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1st (Even though it I not your issue)

On ‎01‎/‎05‎/‎2007 at 20:45, mantadoc said:

fusebox.jpg

 

The fuel pump runs through fuse 7 on a GTE, and those of you who have tried will know you can pull every fuse out of the box but 7 and a Manta will still run.

 

So what's the point? Well if your injection relay goes you can usually limp home like this, a copper coin bridges either fuse 6 or 8 to 7 to power the fuel pump. Leave the injection relay in place when doing this or the injection won't run.

 

Other uses:

  • Ran out of fuel and don't want to flatten the battery cranking while you wait for pressure
  • Emptying the tank / flushing new pipes
  • Finding out which is the feed if you don't trust going by pipe position
  • Some muppet connected an imobilizer / cut out switch badly
  • Fuel pump live will back feed to ignition, so you can pull the key out and leave the car running

 

 

Downsides, if its a poor connection the coin can get hot so don't melt the fuse box

 

No warranty implied or given.....

 

sig.jpg

Say what you like it's still a 1991 Manta

 

Second..........................

On ‎08‎/‎04‎/‎2010 at 21:40, mantadoc said:

Sunday 28th

 

Dusted the car off with a soft 4" brush. The cardboard and sheets have protected the paint quite well but now I remember why I never wash cars.

 

j20100328_00.jpg

 

Drove out under it's own steam.

 

j20100328_01.jpg

 

Testing Mr Cheeze's coil and amp.

 

j20100328_02.jpg

 

The pin in the yellow ring had gone dodgy, so piggy backed on the one in the red ring. On a non-Jetronic car you can bypass this and only lose the rev counter, on a Jetronic car the pulse is needed for the injection. Some of the wiring looms (different car end and ignition amplifier end) do away with these and just use fance male and female spades, similar to the black wire. The spade type was the type I sent Mr Cheeze.

 

I'll be soldering this up heat shrink sleeving it later.

 

j20100328_03.jpg

And if you have a good spark and rev counter working then I'll start asking proper question.

Your car runs on the cold start injector because that lasts for about 30 seconds using the thermo time switch and is not linked to firing plugs.. If the green plug to rev counter is faulty or disconnected you can have no spark or if bypassed a 1.8 runs fine but a GTE does not. basically if the green from the amp goes straight to the coil and the one to rev counter dangling that is 90% your problem.

9 hours ago, Snowy said:

You're making one of the most simple fuel injection systems sound more complicated than it is.

You have a stand alone loom that has a live connection, and earth and a four pin plug.

The issue is very simple. You either have a wiring fault, bell out the injection loom, or component failure. Test and replace.

^^^^^^^^^^^^^This

 

Plus make sure the  4 wire multiplug on the injection loom (connected by heater fan connections) is in good order.

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