Car starts then cuts out immediately

[Gavin Waddell 18]

Alright Then i was sold it as a MP3.1?

I’ve been running through the wiring diagrams checking for continuity, and it all seems to be able to work with the 205’s original wiring. It’s just the big brown relay has a few wires cut and wanted to trace them.

 

Thanks Gavin

 

[Gavin Waddell 18]

Ok so little update, I went to the car this morning. I I bridged the tach relay to 87a and 87b? With power and still nothing. So i put the tach relay back turned the key pump primes stuck a light probe on one of the injectors to see and we have power. Tried to start it nothing!

 

so I got out the brake cleaner sprayed à heathy dose inside the AFM and it started for a couple of secs then died. Meaning no fuel injectors not spraying. Now why? It’s got a new ignition amp and temp sensor.

 

any ideas?

 

Gavin

 

[Gavin Waddell 18]

Could it be a dodgy ground? The écu grounds the injectors to fire?  

Akso tach relay, ing amp, and the coil? If all of these don’t ground car won’t start?

is there a way to jury rig a ground on the ecu, like adding a growing to the pin?

 

gavin

[Telf 224 2 Cars]

Gavin I've just read through this, can you clarify is it an original ECU/engine loom or aftermarket/modded?

 

Also have you actually tried a different ECU?

 

Have you tried a different AFM?

Edited January 20, 2020 by Telf

[Telf 224 2 Cars]

On 11/20/2019 at 7:43 PM, Gavin Waddell said:

Aussie frogs where some one had the same trouble. Now they said to unplugge the écu temp sensor because if it shorts out the écu won’t fuel properly. Forgot to mention I pulled the injectors out and they weren’t firing.

So tonight I went to the garage tried to start it and nothing. Unplugged the afm and it Started ?

Reading this I think you have a short to earth somewhere. 

 

As I understand it if the coolant sensor is earthed the ECU won't allow the car to start. Have you checked the sensor wiring for a short to earth? Likewise have you checked the wiring from the AFM for a short condition?

 

Ordinarily a shirt to earth would remain regardless of the sensor or AFM being connected. I mean the ECU would still sense it but have you rules out any shorts?

[Gavin Waddell 18]

Thanks telf

 

ive made up a list of all the engine management plugs and I’m going to work my way through it and see what I can find. 

 

Thanks for the advice 

[Gavin Waddell 18]

Here’s abut if a dumb question how to you check a short? 

 

Gavin

[Telf 224 2 Cars]

 

Hi  ok so it's pretty simple 

 

Whatever wire you are testing make sure it is disconnected from the load (eg a bulb etc) and supply.

 

Connect the -ve lead if the fluke to a good known earth - like the gearbox earth. Connect the +ve lead to the wire. 

 

If you get continuity(zero ohms) then you have a short to earth

See pics

Edited January 23, 2020 by Telf

[jackherer 543]

34 minutes ago, Telf said:

Connect the -ve lead if the fluke

Other (cheaper) multimeters are available

[PhilNW 44]

Whats makes you think it is electrical?

 

Whats the fuel pressure like? 

When the pump primes it can get enough to the injectors but will reduce rapidly when it starts. 

[Gavin Waddell 18]

Hey telf

 

Thanks for that.

 

just to recap:

1.set ohm meter to continuity

2. Unplug injector plug and tick +ve in one pin and, - ve on battery terminal.

3. Look at ohm meter and should not read zero.

 

looking through the wiring diagram a lot of the components for the engine management our joined together? Meaning I could have a short to earth any where ?

 

phil: I reckon it’s electrical because when I spray easy start Int the inlet it starts .

you reckon there’s not enough fuel pressure ? Pinch the return line and see if that helps?

 

Thanks Gavin

 

[PhilNW 44]

15 minutes ago, Gavin Waddell said:

phil: I reckon it’s electrical because when I spray easy start Int the inlet it starts .

you reckon there’s not enough fuel pressure ? Pinch the return line and see if that helps?

How long after the squirt of easy start does it run for? If it is starting that suggests to me electrical is good  just short of fuel

Confession - I was trying to diagnose a problem years ago and with all the failed attempts at starting I realised I had run out of fuel ! 

 

Pinching the return line may not affect the pump pressure if it is not adequate in the first place

 

Edited January 28, 2020 by PhilNW

[PhilNW 44]

Another issue I found on mine was the wires in the connector to the AFM, check how good they are as they could be sending the no/bad signal to the ecu. I ended up cutting off and replacing the  4 terminals in the plug and all was good

[Gavin Waddell 18]

Thread ressurection.

 

Car still wont start So i thought F**k it and started to strip all the insulation off the wiring loom to see whats what. all the connections seem fine so deide to start checking continuity.

firsth i started with the 2 white wires that supply power to the different components such as AFM TPS injetors. i found the where they all split up and checked just before that to ecu and all was fine. THen checked from each plug to the split all was fine. so i then checked all the grounds that go to above the gearbox and all was good.

 

so i decided to check power at the tach relay, big brown wire is getting 12v, checked the 2 white wires and they also get power but only 10v? so i remebering seing a post where you can bridge the connections to get power to pump and injection componets. did that pump stays on but still nothing, checked power at injectors 10v.

 

If i am right in thinking the ecu grounds the injectors and they fire ? now that i can see all the wires i checked  the  injector ground which runs back to the ecu, so same a befor checked each plug to before they all connect together all good, then checked from connection to ecu all good.

 

now while doing some research on her i found a post from grim badger where he has mwade a pin out for the ecu

 

Now on the above picture pin 1 on the ecu is for a ground? Is this the ground the ecu uses to ground everything? This ground i guess goes to one off the brown multi plug under the dash? and then  goe to the fuse board. could this be my problem as all the under dash connections seem fine.

Or am i complelty wrong

 

Thanks Gavin

 

[Gavin Waddell 18]

Any one? Wiring gurus ? I need help! Please.

 

ok Il stop begging.

 

Gavin 

[PhilNW 44]

Quote - The car starts the dies as soon As you apply the throttle. It has spark and fuel, when i unplug the airflow meter it runs albeit  a bit lumpy soon as you plug it back in nothing

Question - AFM plug, of the 4 wires are they actually on the right terminals at the AFM?

 

Quote - Pump is new and runs with direct feed

Question - is pump brand new or 2nd hand? and have you confirmed the actual pressure it is delivering and is fuel actually going through the injectors??

 

Question - Is the spark at all the the plugs and/or distributor and/or coil?

 

As the thread is now getting a bit long , can you summarise what works and what does not? 

[Gavin Waddell 18]

Ok lets try and fo a recap

 

1.pulled the car out of hibernation, started drove it to my house. next day tried to start it no joy.

-checked spark all good.

-checked to see if there was fuel at the rail -good

           -car had a dodgy fuel pump so replaced it with an ali express special.

2. Couldnt leave ther car where it was so remembered unplugging  afm might work. car started albeit very rich.

3. if i plug in AFM and disconnect CTS car all so starts but runs rich . WHich is wierd

Once at the work shop started to go through the engine bay to see if anything was loose unplugged-nothing

- Checked to see if fuel was comin gout of the injectors and they were dry -So fuel to rail butnot to injectors

-Bought some easy start sprayed a good dose and car fired up- Confirming injectors arent getting fuel.

-Searched the internet and found article about bridging tach relay - bridged the relay, fuel pump on continously still no start.

-Started checking tach relay-Checked power to big brown wire 12v- checked 2 white wires 10v? still no start

-Remembered the wiring was a rats nest under the manifold so started stripping insulation off the wiring loom.

-Started checking continuity of the wires.

        -checked continuity of the 2 white wires that bring power to AFM TPS CTS SAD injectors. before they all split continuity was good.

       - checked each wire from plug to split, continuity was good.

-Checked all the earths to top of gearbox everything was ok.

-Checked earth from injectors to ecu and all was ok.

-Tried pinching fuel return line to increase pressure no joy on starting.

-Retracked AFm also.

 

Thats about where i am now. car still doen start.

 

thats why i asked if any one knew where the ecu earth point is, like i pointed on Grim Badgers post above the ecu earth point is pin one which runs to where?

i reckon i have a dodgy earth and the ecu cant ground the injectors to make them fire?

 

Any ideas?

 

Gavin

 

 

[welshpug 1,661]

so it runs with cts or afm unplugged?

 

test them.

[PhilNW 44]

First thought try replacing the terminals on the AFM, corrosion/dirt caused me grief in the past! They may look OK but replacing them cured my fault.

Look out for others on the wiring, 

 

Injectors may be not passing enough fuel due to incorrect signals from AFM/ECU

 

 

Edited March 19, 2020 by PhilNW

[Gavin Waddell 18]

I ordered a new cts and checked it with boiling water and all good.

 

i checked AFM using the Haynes method all good. But I think I might try the 9v battery test also

[Telf 224 2 Cars]

Gavin, 

 

On 3/19/2020 at 12:33 PM, Gavin Waddell said:

thats why i asked if any one knew where the ecu earth point is, like i pointed on Grim Badgers post above the ecu earth point is pin one which runs to where?

i reckon i have a dodgy earth and the ecu cant ground the injectors to make them fire?

heres the pinout of the ECU plug:(stolen from a post of Grahams)

 

• Pin 1 = ignition coil.
• Pin 2 = Throttle switch.
• Pin 3 = Throttle switch.
• Pin 4 = Ignition switch start signal.
• Pin 5 = earth.
• Pin 6 = not connected.
• Pin 7 = Air Flow meter.
• Pin 8 = Intake air temp sensor (in AFM).
• Pin 9 = Relay module (tachymetric relay middle pin).
• Pin 10 = Engine coolant temp sender (CTS).
• Pin 11 = not connected.
• Pin 12 = Injectors.
• Pin 13 = Earth.
• Pin 14 - 25 = not connected.

Heres Damirs explaination of the Tachy relay function:

 

 

When starting the engine by cranking it via starter motor , relay being connected to the starter motor positive circuit uses supply voltage from the starter motor for energizing the relay .

Once energized , when the engine reaches cranking speed above 350-400 rpm. it then uses pulse signal from the ignition coil negative terminal for closing the relay contacts thus sending power supply from the relay to the fueling system/sensors and maintaining engine running until switched off by key .

 

Safety measure side of this type of relay is based on the pulse signal from the ignition coil , while it needs minimum of 350-400 rpm. in order to close the relay contacts for supplying power , when or if the engine rotation speed drops below that value the relay contacts will open cutting of the power supply to the fuel system and fuel pump .

 

This type of relay has seven terminals :

 

30 – Battery supply (permanently connected to the battery positive terminal)

15 – Ignition supply (connected to the ignition key ON circuit)

1 – Ignition coil signal (pulse signal , connected to the ignition coil negative terminal)

50 – Starter signal (connected to the starter motor positive circuit)

31 – Earth (connected to the battery negative terminal)

87 – Fuel system power supply (connected to injectors , air flow meter , throttle position sensor , supplemetary air device)

87b – Fuel pump power supply (connected to the fuel pump positive circuit)

 

Common faults caused by tachymetric relay :

 

No start: difficulty starting , no power supply to the fuel system components , engine cutting out after a few min. of driving , fuel pump permanently ON .

 

Causes : Loose or melted soldered joints , oxidized outer relay contact terminals , broken relay coil winding wire , burnt diode or resistor , sticky/oxidized main relay energizing contact points .

 

Distributor Fly lead:

 

 

It provides the timing signal used by the ignition amp for spark (and in turn the ECU for fuel injection)

 

If it's damaged, you'll have no spark/injection (or perhaps intermittently if it's not completely broken but instead has a connection that makes/breaks by movement and vibration)

 

 

What am i telling you?

 

several things are all interconnected. The Ignition amplifier produces an output triggered by the Dizzy. If your dizzy is unserviceable or the fly lead from it or the Amp you are not going to get a signal to the injectors to make them fire. Hence no fuel in the bores. The Tachy relay may be unserviceable and are prime culprits for all kinds of issues.

 

Have you changed the tachy relay? have you checked the dizzy cable etc?

 

The wiring diagram clearly shows all the interconnections. pin 5 and 13 are the earths - you can see on the wiring diagram in the haynes where they connect.(i think at the gearbox stud). There is no magical place that the injectors arent getting grounded from. Also notice that the Tachy relay is connected to one side of the injector coil and the ECU to the other.

[Telf 224 2 Cars]

Here's a diagram of all the connections from the ECU plug to all the components

[Telf 224 2 Cars]

Here's the diagram complete with the connections to the distributor and ignition amplifier

[Telf 224 2 Cars]

sat and reread your post after drawing out these diagrams.

 

Its very confusing trying to fix a 30 year old car so i get your frustration, I'm sure many on the forum have been through a nightmare like this.

 

you say it will only start if the AFM or the Coolant sensor are unplugged.

 

The AFM, Temp sensor,SAD and Tachy relay all share a common earth. Its connected pretty much to the battery via (i think) the gearbox earth. The wiring diagram bears this out. Also connected to pin 5 and 13 on the ECU.

 

They also all share a common supply from pin 9 on the ECU. this feeds the injectors,SAD,Tachy relay and AFM. The coolant sensor output goes to pin 10.

 

Now when you disconnect one of the two units it runs (poorly but it runs).

 

I would disconnect both these units- AFM and Temp sensor. Check the wiring on them - visually also with a multimeter. You need to be sure that you have good continuity with no shorts. A wire should only be connected to whatever it shares a common connection with. eg the injectors,sad,relay and afm on pin 9 for example. do these checks with the ECU disconnected to prevent spurious signals via the interconnections inside the ECU. Basically I'm saying make sure that only the wires are connected were they are suppposed to be and aren't shorted due to damage. this is painful and will take time. 

 

I'd definitely  check the AFM plug as already mentioned- you will have to dismantle it to check properly.

 

Id replace the AFM if you can get hold of one and the tachy relay- do you know anyone who has a working car you can borrow them from?

 

 

 

 

[Telf 224 2 Cars]

On 3/19/2020 at 2:08 PM, Gavin Waddell said:

I ordered a new cts and checked it with boiling water and all good.

 

i checked AFM using the Haynes method all good. But I think I might try the 9v battery test also

reading this- if you are sure the AFM and CTS are good you have to have a wiring issue.