Elan M100 starts but cuts out after 2 seconds

[Todmorden]

Hi new to this forum.  Anyone any ideas on why my car starts and cuts out after 2seconds.

it has fuel it has fuel pressure it has spark the immobiliser is not on .  
we have been thinking is it an injector issue or is it an ECU issue any help greatly received thanks

[exeterjeep]

Probably best to post your query on the m100 main help forum http://forum.lotuselancentral.com/index.php, that's where most of the M100 experts hang out. 

Welcome to TLF anyway.

[Rambo]

Two questions that spring to mind.

1. Can you actually hear the fuel pump prime? 

2. Check that the inertia switch, next to the battery, is in the down position.

[jep]

I had this on an Elise S1. Fuel pump. Particularly when below 15 litres of fuel. The car would start, run for 2 seconds and conk out.

Once it failed in motion, just stopped. I filled the tank and it was fine. 

We changed the pump, fine since though we tried other electrical fixes before doing this. 

Just a thought, not necessarily the solution. I also don't run the tank low now, 1996 car and tank is dirty. I'd replace it but can't find a 38 litre original. New ones are 48 litre aluminium, I'd like to stick with 38.

Justin 

 

[Escape]

That does sound like a fuel delivery problem. You say fuel pressure is OK. Have you measured while trying to start? Is there enough flow? Sometimes the pump will deliver just enough to prime the rail for starting, but can't cope when the injectors are operating.

[Rambo]

There is also a small fuel pump relay to consider. If it has failed or been dislodged in some way the car won't go, hence my question on whether you can actually hear the fuel pump working prior to ignition.

How long have you had the M100 and has it been running normally prior to this issue?

[Todmorden]

Thankyou all for your replies 

a bit more information the car hasn’t run for 12 months.  The fuel level is or was extremely low it is now 25 litres fuller so we shall try again.

the inertia switch is down and as far as I can see always was.   
the fuel pump runs for approx 2 secs before  it starts. 
the theory of a weak fuel pump is definitely something I will try .  
I can’t answer the question on fuel pressure as I didn’t do the test I will however find out . For clarity it literally fires on first turn of the key and timed cuts out exactly 2 secs after firing.

mileage is around 100k.  
Any ideas on a good parts supply as the car is new to me and I did buy knowing it wouldn’t start .  I have a huge history file going back 27 years it has been well looked after .

could it be injectors ? And could it be a faulty ECU?

thanks again 

 

[jep]

Bad fuel? Drain tank and fill with premium unleaded. Except you've added 25 litres! 

Blocked fuel filter? 

Justin

 

[Rambo]

I would have drained the tank and changed the fuel filter(fiddly) before adding new fuel 🤔

I believe there is also an in line pressure regulator before the fuel hits the injectors.

Injector problems have occured fairly readily in the last few years on M100's. My theory is cars sitting around, old fuel and also people putting in cheap supermarket and/or E10 fuel.

If you diagnose the injectors as being at fault it is better and cheaper to refurb. your own.

Incidentally do you get an orange CEL displayed. If so, have you diagnosed the fault codes? (paper clip test)

[exeterjeep]

33 minutes ago, Todmorden said:

good parts supply as the car is new to me

SJ sports cars in Crediton and South West Lotus are knowledgeable on the M100. SJ have a good web site for ordering parts.

Where abouts in the country are you? There are other parts suppliers, but these days some parts are almost unobtainable/expensive.

[Rambo]

Don't forget Pete Musgrove at PNM. Or the former Paul Matty crowd 😉

[Todmorden]

West Yorkshire based Todmorden specifically.

I will report back on the progress thanks for the advice.

fuel wise never thought should have cleaned it out .  So will go back to basics . Clean fuel tank new fuel filter and for good measure I’m going with the fuel pump.  Looking at the replies the online pressure regulator too.

no idea on fault codes but will find out . 
noted

on the injector refurb

thanks everyone 

[Escape]

Don't just throw parts at it. A new fuel filter is probably a good idea, but with the problem occurring so regularly, it's unlikely to be a blockage. Bad fuel would effect starting as well, not just make the engine cut out. Same for injectors, you'd expect bad running or not-starting, not cutting out like that.

Testing fuel pressure and flow should tell you if the pump and regulator are OK or not.

[Steve V8]

Why have you ruled out the immobiliser? 

Running for 2 seconds then cutting out is also a standard immobiliser module fault.

[Rambo]

I would agree. If its an aftermarket immobiliser there have been lots of problems reported on M100. And I would be doing the simple, most logical things first, not just chucking money and parts at it.

PS is your car yellow by any chance? If so, be prepared for a barrage of questions. I just hope it's not "Lucky, the basket case!" 🤔

[Todmorden]

No it’s blue!!! 
 

it is an aftermarket alarm immobiliser the reason I’m steering away from it is because when you try to start the car nothing at all happens with the fuel pump until you press the alarm button then you can hear the pump prime . 
I should be able to report back tomorrow if fuel pressure is ok.  
thanks again

[exeterjeep]

My S2 had its aftermarket alarm removed early last year by SJ for the previous owner. The original factory one having failed years ago. They do seem a problem n M100 - especially S2.

What model  / year is yours - and good to hear its not the yellow one that Rambo refers to.

Also on the LEC forum there is access to the various M100 manuals/parts lists.

[Escape]

If there is clear evidence of the immobiliser affecting the fuel pump, as you describe, I'd try to do a quick bypass (bridging the fuel pump relay should be enough). If that solves it, you can still decide to try and fix the immobiliser or just remove/bypass. I don't think out classic Lotus are much at risk of being stolen anyway. First thing I did to my Esprit was remove the immobiliser. It had already acted up when we needed to board the ferry on the drive home, once was enough. 😉

[Rambo]

Hotwiring it to bypass the immobiliser and fuel pump relay is relatively easy, particularly with a circuit diagram.

We did it last year at Silverstone and it fired up 1st time. 

PS you're fortunate you didn't buy "Lucky, the basket case" as someone had stolen the ECU and the owner wondered why it wouldn't start 🤣

[exeterjeep]

1 hour ago, Rambo said:

PS you're fortunate you didn't buy "Lucky, the basket case" as someone had stolen the ECU and the owner wondered why it wouldn't start 🤣

Thought his advert said it ran...... but no one knew why...but he showed pics of the ECU missing - well just the wires that should have been attached to it. There is a long thread on LEC forum about 'Lucky' I wonder where it is now.

[Todmorden]

Sorry it took so long to reply however….

4xnew injectors and the car fired up first time!!

took for test passes with no advisories.

thanks for your suggestions everyone