Starts up and then immediately dies

Technical Area Engine, Transmission, Exhaust etc
2

Hi - in a nutshell my 1996 Eunos Roadster 1.8 Auto V-spec starts immediately the key is turned but then equally immediately dies. This can be repeated time and time again - it bursts fully into life as if all is well, then dies.

As I am new to my Eunos I am a bit at sea with all the complexity of the system (the last two-seater sports I had was a Spitfire 4!).

To give the background to this…

The car had been laid up for three years when I bought it from a colleague. On replacement of the battery it started without problem and I drove it straight down for an MOT (passed with no issues) and had a basic service. On collecting the car I drove a mile or so home with no problems and parked it on the drive. I started it once on the drive and the engine ran fine. Then I started it again and it died, and while it turned over, the engine was lifeless.

I consulted my Rod’s manual and started to work through things starting with the checking fuel pump/relay system. The fuel pump relay was fine but when I jumped the F/P to GND on the diagnostic block the fuel pump wasn’t working - actually, it didn’t, then did, then didn’t and then wouldn’t anymore.

I got the tank connection exposed, disconnected it and checked that indeed 11.odd volts were present at the connector, but when the pump was connected the load was such that the f/p relay immediately dropped out. I surmised that there was too little current in the circuit and checked the B+ on the diagnostic block to GND and got only just over 11 volts despite having 12.5 at the battery. As I was informed that the only thing between the battery and the B+ terminal was a 30Amp fuse and the main relay, I replaced the relay and the fuel pump is now running fine. Presumably the relay contacts were corroded or not making good contact - though even with the replacement I am only getting 11.9 volts at the B+ terminal now?? I also checked the grounding off the tank connector and the two GNDs off the diagnostic block and they all appear fine.

Anyway, that apparently fixed I was first elated that on turning the key it started and then dismayed immediately as it died as I have outlined above.

Now I know I should and will make up the diode/LED and check for any error codes, but could anyone who has more experience of the system suggest what could be the issue? What could possibly allow the engine to start so easily and well then cause it to die equally instantly?

The one thing I suppose could be a partially blocked fuel line and because the car stood for three years and was near to empty it could be that after driving it and sloshing the fuel around in the tanks the filters are semi-blocked. I added a gallon of new fuel with additive and rocked the tank to help clear any blockage, but that hasn’t helped. As the main fuel filter is right under the car and so is difficult to access is there a simple way to check that the fuel is getting through the system with the required ease? I thought that checking the flow in the return line at the connection on the tank would be easiest (as I still have the carpet and cover off) but this is best avoided if the problem is likely to lie elsewhere.   

Thanks in advance for any experience you can bring to bear on this. Of course I could just simply, if expensively, get it towed off to the nearest dealership, but I want know my way around it technically as I bought this car as an enthusiast, and so it is a bit frustrating to be stalled before I get chance to get any real familiarity with it. 

Paul C

 

 

 

3

A dealership won’t have a clue (OK, Robbie might). Many of the current “technicians” won’t have had a Mk1 in the workshop before.

As you surmise, it’s bound to be fuel supply UNLESS the car has an immobiliser, because some of them behave exactly as you describe - the engine will start and immediately die. Change the filter anyway; it’s often neglected and it isn’t too hard to do.

4

I have just watched a really good video on youtube called Mazda Miata Fan about changing a fuel filter it maybe worth checking out

5

Sounds llike the symptoms of a missing IGF (IGnition Fire I think) signal to the PCM, especially if the cutting out happens at exactally the same time interval each time. If the PCM doesn’t see the IGF singal when it switches from it’s start up map to it’s run map it shuts off the fuel. It’s the fuel cut off control in case of an accident, engine stops running, fuel pump stops. Depending on whether it’s a 4 or 3 wire coil pack depends on where that signal comes from, I can’t remember the exact details right now. If you quickly turn the ignition repeatably on and off once it’s fired will it keep running? I’ve known of a failed coil pack taking out the PCM giving those symptoms before.

6

Thanks for those pointers. I was wondering if it was either or all of your suggestions (immobiliser, fuel or the ignition sequenced under control of the PCM - the actual start-up sequence of events that the PCM controls not really explained in my Rod’s manual). Immobilisers are the pains as I have no documentation - it is a Toad - and so no idea how to check it’s operation.
I will try the check that Robbie suggests and take it from there. Changing the fuel filter is inevitable, but it just does feel to me as I hit the key that the fatal problem is an ignition system issue. Thanks again

7

Spot on it seems - yes, I can keep it running if I repeatably re-turn the key and so that would seem to eliminate any fuel system blockage and so it looks more like the issue you suggest. I have tried to look through the wiring diagrams and my manual but cannot work out where/what to check next.

Paul C

8

What’s your VIN?

9

I had a simerlar problam on my S-Ltd, In the end we did a dianostic useing the Mazda 7 pin connector there was 45 faults, cleared the faults down and diconected the battery waited abour 2 minutes re-connected batery and she fired up and has continued to do so. I have since been told that all you need to do is dissconect battery waight a bit, have a cuppa re-connect battery then off you go. Might be worth a try.

10

Thanks for getting back to me so promptly - I already owe you a pint or two!

NA8C-301183

11

Thanks for that - certainly worth a try, and I’m always up for a tea break! 

12

How long does the car run before it dies? 

I’m not familiar with the IGF fault that Roadster Robbie describes so I don’t know how long it would run in those circumstances before cutting out, but I recall when i once forgot to plug in the AFM on mine it started but then the revs immediately dropped and it cut out.  If I remember correctly I could keep it struggling along for a bit by giving it a bit of throttle, but it really just wanted to die.

13

Hi - I recorded a sound file, but cannot work out how to upload it to the page. However, it is basically immediate and it lasts as long as it takes to say Burrum…dead - if that makes any sense! Now I will show my absolute ignorance by asking you please what is the AFM - I’m definately suffering acronym overload when it comes to the fuel, ignition and engine mangement systems!

Cheers for the response.

14

Thanks for that - beats trying it out on a precariously balanced car in the scrap yard which I sometimes try to do to practice and to find the pitfalls before trying things on my own vehicle. I normally wreck the first one of the multitudinous varieties of plastic clips before I work out how they attach and can remove the rest sucessfully in a reusable state.

Paul C

15

I take it the car has 3 wire coils. If so, your’s is the later type and I don’t think it uses an IGF signal externally from the coils. You really need to find out if fuel injection, spark or fuel pump is inhibited once it has cut out (without turning the ignition off).

16

Robbie - well the fuel pump is certainly running on after the engine dies, but whether it falters duing the short time the engine is running will need to be checked out. Checking the spark isn’t a problems, but I am not sure how to check if the fuel injection is cutting out. Anyway I cannot do anything about it for a few days as I am going away (in my very old Nissan Micra which the Eunos should have replaced by now!). Thanks again for the help so far with approaching this logically.

Paul C

17

Sorry about that.  It’s all too easy to just slip into acronyms.  AFM = airflow meter.  It sits on top of the air filter box and it also incorporates the intake air temperture sensor.  Make sure the plug is firmly seated.

18

Don’t rule out Martin’s air flow meter theory, I think your car is a later model than the one I had with the missing IGF signal fault. have you tried giving it some throttle to keep it running?

19

Again, spot on the money! Earlier today, before I read your reply, I got in and it started and died as usual, and when I hit the throttle harder it still made no difference. However, I then discovered that if keep rapidly stabbing the accelerator down just a bit it will indeed keep on running - and I am much happier as a result. So is that a sign of a problem with the air flow meter? When you hit the pedal doesn’t the system inject some fuel by another mechanism until the revs pick up - I think I read that somewhere?

20

Hi - I thought I would get back to you all just to say that despite doing more checks I am still no further forward with this and hope that someone might have a last thought on this before I reluctantly have to admit defeat and send it towed off to a garage.

To recap the problem - turns over and starts immediately but then equally immediately dies. Turning the ignition on and off will keep it running as will stabbing shallowly the accelerator peddle.
Tested/replaced main relay, fuel pump/relay, both fuel filters, air flow meter, and generally all obvious connections.

Some new information is that if I run the diagnostic check on data link box I get one LED flash which is an IGF fault.
Now although Robbie used my VIN and suggested I only had the later three wires to the coils as per the 1996 (1996 is the recorded registration date) wiring diagrams I have on further checking I seem to have the 1994 wiring with the extra blk/wht IGN pulse wire. (As an import I assume that it’s pedigree could be a bit mongrel! According to the previous owner my Eunos is a bit of a special V-special as it has big chrome door mirrors and chrome wheels)
Anyway, this pulse drives the tachometer on the 1994 system so the suggested test is to check the tachometer which is indeed responding when the engine starts up so the pulse must be there but might not be getting back to the ECM computer so that is one last check I need to do.

Any other ideas would be welcome. - cheers.