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pits

Original Poster:

6,423 posts

189 months

Thursday 19th May 2022
quotequote all
Getting a bit confused on this one.
Disarm immobiliser
Turn key
Fuel pump primes
Gauges work.
Car cranks
No spark
No fuel.

I've got fuel up to the rail on priming and on return, but after constant cranking plugs remain dry.
I've tried a second coil and ignition amp
I've got 12v to coil.
No spark at HT
No spark at King lead
Won't start on easy start either

I've got a spare pump, but it's priming, and I'm getting fuel to the rail, so I am discounting that.
Immobiliser I can discount as well, from reading I have fuel pump priming, and my fuel gauge works.

That I guess leaves relays? As far as I can gather the ecu/alarm requires both fuel and spark for both to work? I've got a spare injector which is a known refurbished item, so I can probably connect that to the engine loom and put it in some petrol or yurps to see if it pumps, but the plugs on both sides remaining dry after cranking, tells me that whilst fuel is at rail, there is no signal to open the injectors.

QBee

20,904 posts

143 months

Thursday 19th May 2022
quotequote all
I have had a similar happen when the car stalled on me.....in the middle lane of three at a busy dual carriageway roundabout.

On that occasion locking and unlocking the car solved the issue, as it reset/unset the immobiliser.
It does sound like the ignition/injectors side of the immobiliser is still set.

One other top of the head suggestion - you could try re-setting the ECU by simply unplugging it and then connecting it again after a few seconds.

pits

Original Poster:

6,423 posts

189 months

Thursday 19th May 2022
quotequote all
QBee said:
I have had a similar happen when the car stalled on me.....in the middle lane of three at a busy dual carriageway roundabout.

On that occasion locking and unlocking the car solved the issue, as it reset/unset the immobiliser.
It does sound like the ignition/injectors side of the immobiliser is still set.

One other top of the head suggestion - you could try re-setting the ECU by simply unplugging it and then connecting it again after a few seconds.
Very early car so no fob, just the touch key and central locking on key.

I will give the ECU a pull now and see what happens, and get onto the chap who fixes the alarms.

rigga

8,727 posts

200 months

Thursday 19th May 2022
quotequote all
Fuel at the rail is ok, but if the injectors have no electrical feed, it won't matter, get hold of a noid light, and see if the injectors are getting the signal to operate.

No ignition spark also says its Immobilizer at the source of the problem.

Classic Chim

12,424 posts

148 months

Thursday 19th May 2022
quotequote all
Indeed. just get someone to crank it over and put your hand on an injector. You should hear it clicking open/ closed if it’s getting a signal and operating properly.
You can use a simple long reach screwdriver and put the tip on the metal of the injector and the handle to your ear. You should hear or feel the injector clicking.

Edited by Classic Chim on Thursday 19th May 16:21

Classic Chim

12,424 posts

148 months

Thursday 19th May 2022
quotequote all
For interest.
I had a vaguely noisy top end once. Just a slight knocking/ tapping sort of misplaced sound. Put some injector cleaner/ lubricant in the fuel and bobs your uncle engine was much less rattly after. Injectors can clatter away so the lubricant effect must have worked. It’s Definitely worth using every now and then I feel.
I bet your problem is immobiliser if an ecu re set doesn’t get them working.
Can you just put a live feed on our injectors and a ground to earth on the other terminal to trigger them without damaging them? It’s an old trick used to get sticky injectors working on early EFI systems on things like the Jag series 3 XJ6 cars that have stood for ages and only running on 3 or 4 pots. Often it’s a sticky injector not ignition.
Only put the feed to it for a few seconds at a time after removing wiring to that injector as the injector will heat up. Just touch it on/ off until you hear injector clicking.
Nothing to do with this issue I dare say but well worth knowing if your a diy mechanic looking at a car running rough on certain cylinders only and no clicking from an injector.




Edited by Classic Chim on Thursday 19th May 16:41

Belle427

8,858 posts

232 months

Thursday 19th May 2022
quotequote all
Does the fuel pump run when the engine is cranking?
Just make sure all your connections at the coil are good.

pits

Original Poster:

6,423 posts

189 months

Friday 20th May 2022
quotequote all
Well battery has died, and it is chucking it down, so I guess I will have a look at it tomorrow.

Injector I have a spare one so I can just plug it in and see what it does when being cranked, I also have spark plug test light things as well, if the ECU reset doesn't work, is there an immobiliser bypass? Just so I can figure out what it is and get the unit replaced or repaired.

Loubaruch

1,164 posts

197 months

Friday 20th May 2022
quotequote all
If you have no spark then the fuel pump will not continue to run after the initial prime.
It looks very much like something in the ignition LT circuit including all the connectors and immobiliser.
Send me an email and I can forward the immobiliser schematic

Belle427

8,858 posts

232 months

Friday 20th May 2022
quotequote all
Some good info here regarding the initial start up sequence, just make sure the dizzy is actually turning when you crank the engine.
http://g33.co.uk/pages/technical-fuel-injection.ht...

NMNeil

5,860 posts

49 months

Friday 20th May 2022
quotequote all
Start by retrieving any codes that have been stored.

pits

Original Poster:

6,423 posts

189 months

Saturday 21st May 2022
quotequote all
Break in the weather.
Pretty convinced it is now alarm or immobiliser.
Pulled return feed from fuel rail, initial prime came through, cranked and nothing so no fuel pump, obviously fuel pump isn't dead because it is priming .

I have a pinout for the old alarm, but I am now wondering if that even still works, so I will get the multi meter out and start doing some checks on if I am getting power out, If I had the proper know how I would just pull the whole alarm system out and the Meta and just start again with a new unit..

Steve_D

13,737 posts

257 months

Saturday 21st May 2022
quotequote all
If the immobiliser was the issue the pump would not prime.
During crank the ECU is looking for the pulse from Coil negative/ignition amp if you have confirmed you have spark then you are looking for the whit/blue wire that goes from the coil to the ECU.
Until the ECU sees this pulse it will not switch the pump back on.
The wire goes across the front of the engine, behind the dizzy, behind the injectors on the nearside then there is a connector (single pin) which is often cable tied under the air inlet hose. From there it goes through into the footwell. In the footwell loom it goes to the ECU. Somewhere in the line is a 6.8K ohm resistor but I can't at the moment remember where it is located.

I'm pretty confident this is not immobiliser.

Steve

Loubaruch

1,164 posts

197 months

Saturday 21st May 2022
quotequote all
Steve_D said:
If the immobiliser was the issue the pump would not prime. Steve
On my car the fuel pump circuit is not immobilised directly: Only two circuits the ignition and cranking are immobilised.

The fuel pump certainly primes irrespective on whether the immobiliser is functioning or not as the command comes from the ECU, no immobilser connections.

If the ignition circuit is faulty and thus no spark then the fuel pump cannot operate and is thus immobilised indirectly as the ECU demands feedback from the ignition circuit to initiate the fuel pump.

Steve_D

13,737 posts

257 months

Saturday 21st May 2022
quotequote all
Loubaruch said:
Steve_D said:
If the immobiliser was the issue the pump would not prime. Steve
On my car the fuel pump circuit is not immobilised directly: Only two circuits the ignition and cranking are immobilised.

The fuel pump certainly primes irrespective on whether the immobiliser is functioning or not as the command comes from the ECU, no immobilser connections.

If the ignition circuit is faulty and thus no spark then the fuel pump cannot operate and is thus immobilised indirectly as the ECU demands feedback from the ignition circuit to initiate the fuel pump.
So has your car been wired differently?
Where does the supply to the fuel pump relay coil come from? The cars I have been involved with fuse 12 is supplied direct from the ignition switch and supplies, ignition coil, ECU pin 19 & the coil of the fuel pump relay all via the immobiliser.
So, whilst the supply to the fuel pump via the relay is not immobilised the relay is.

Steve

pits

Original Poster:

6,423 posts

189 months

Saturday 21st May 2022
quotequote all
Steve_D said:
If the immobiliser was the issue the pump would not prime.
During crank the ECU is looking for the pulse from Coil negative/ignition amp if you have confirmed you have spark then you are looking for the whit/blue wire that goes from the coil to the ECU.
Until the ECU sees this pulse it will not switch the pump back on.
The wire goes across the front of the engine, behind the dizzy, behind the injectors on the nearside then there is a connector (single pin) which is often cable tied under the air inlet hose. From there it goes through into the footwell. In the footwell loom it goes to the ECU. Somewhere in the line is a 6.8K ohm resistor but I can't at the moment remember where it is located.

I'm pretty confident this is not immobiliser.

Steve
Confirmed no spark, I have those see through leads and confirmed no spark.
I have had a look at my wiring and there are no white/blue wires.
My coil goes, yellow single, into yellow/white and white/yellow.
Other side of coil goes white/green into a solid white and white/black (it has had some wiring done at the end but the loom is original, at the ignition amp there is no white/blue either.

It's an early car if that helps, I have also dragged all the loom out and fusebox out, I will try another ignition amplifier first as I know I have 12v to both coils that have been tried.


Loubaruch said:
On my car the fuel pump circuit is not immobilised directly: Only two circuits the ignition and cranking are immobilised.

The fuel pump certainly primes irrespective on whether the immobiliser is functioning or not as the command comes from the ECU, no immobilser connections.

If the ignition circuit is faulty and thus no spark then the fuel pump cannot operate and is thus immobilised indirectly as the ECU demands feedback from the ignition circuit to initiate the fuel pump.
On my car the pump will not prime without the touch fob being used.

Loubaruch

1,164 posts

197 months

Saturday 21st May 2022
quotequote all
Apologies, Steve is correct!

No my car is not wired differently I fear that Iam!

Senior moment again I am afraid.

Belle427

8,858 posts

232 months

Saturday 21st May 2022
quotequote all
Id agree that if the pump primes its not the immobiliser.
You also said you had 12 volts at coil positive so to me if the car cranks over ok it can't be immobiliser related.
Sounds to me as if the signal isn't getting back to the Ecu to fire the injectors.
There are some testing methods below.

http://g33.co.uk/pages/technical-ignition-system.h...
Edited by Belle427 on Saturday 21st May 15:12


Edited by Belle427 on Saturday 21st May 15:15

Steve_D

13,737 posts

257 months

Saturday 21st May 2022
quotequote all
Loubaruch said:
.....Senior moment again I am afraid.
I have those. very senior(73)

steve

pits

Original Poster:

6,423 posts

189 months

Monday 23rd May 2022
quotequote all
Belle427 said:
Id agree that if the pump primes its not the immobiliser.
You also said you had 12 volts at coil positive so to me if the car cranks over ok it can't be immobiliser related.
Sounds to me as if the signal isn't getting back to the Ecu to fire the injectors.
There are some testing methods below.

http://g33.co.uk/pages/technical-ignition-system.h...
Edited by Belle427 on Saturday 21st May 15:12


Edited by Belle427 on Saturday 21st May 15:15
That is quite helpful actually, I have just fitted a new ignition amp to rule out the other two older ones and still nothing, I have power to the connector on the amp, so I will try the trigger head test next.

I have had a search, where can I get a new trigger head? All I can find is the upgrade kits, or is it just a case of a new dizzy?