M100 Not Starting (another one!)

[riksit2000]

Hi all, looking to tap into this string of comments. I've got a similar starting issue that is very similar, but proving extremely difficult to resolve, so hoping for some expert opinions.
Quick scene setting. Cam belt changed, water pump, etc. Car started without issue immediately after, so moved on to other work. I've had the bumper off to realign, on off several times to sort it out (it's been in a bump prior to my ownership). Tried to start it two weeks ago, engine fires up then dies off instantly. I've carried out the following:
New battery
New fuel filter
Injectors checked for operation, all clicking with 12v applied.
I can see spark via timing light
New plugs fitted.
Unplugged all electrical plug connectors that I believe are linked and re-seated them.
Stripped the cam belt cover to double check set up is correct and as I left it, it is.
Made a ECU adapter and connected laptop, shows noting that rings any alarm bells.
New fuel.
All to no avail, so far.
I can rev the car at start, but it feels like it's running on two cylinders, dies off as soon as accelerator is released. I have noticed that if I hold the accelerator in a certain position it will 'roughly' rev to around 3000rpm and drop off to around 1000rpm, rev to 3000rpm and drop off to 1000rpm, repeating this cycle - no movement of accelerator.
I have also noticed that if i charge the fuel system (ignition on, let pump run) and then pull the inertia plunger, the car starts and runs until the fuel runs out: looking at the electrical drawings, the thing that stands out is that the fuel pump relay feeds a signal into the ECM, could this be faulty, if so, how do I check?
I haven't checked the fuel pressure relief valve as yet.
I can't help thinking I've disturbed something as I've been working???
A strange thing happened last night in that when I pulled the inertia switch plunger, the car seemed to run on for quite a while, like 10min or more, I actually turned it off. However, this was a one off and I cannot replicate. I've questioned myself a few times as to whether I actually did see this! I did!
I'm thinking my next step is to run a supply to the fuel pump direct, pull the inertia plunger and try to run it to see if it keeps going.
Any thoughts on what to do next would be very much appreciated, it's now doing my napper in!
TIA

[esprit888]

I always lean towards there is no such thing as a coincidence. I would Triple check cam belt timing and tension before digging a deeper rabbit hole, was the tension set at TDC or the correct way? How was the weight/pressure applied to the belt to obtain correct tension. I’ve done over two dozen timing belts on Lotus Esprit and M100 yet I somehow managed to mistime an Esprit recently (in my defence the dots on the cam pulley were wrongly oriented but I still have a lump where I smacked my head )

[riksit2000]

Can one of the moderators or head honcho's (Dave, Geoff et al) please separate this into another thread otherwise it is going to get confusing

PS do you hear the fuel pump prime when you turn the key?. It sounds fuel, fuel pump related ?? Another thought, try disconnecting the battery for a few minutes and see if the ECU resets itself. Worth a try, costs nothing, but you will lose any error codes so maybe do a paper clip test beforehand to see if there are any error codes stored

Apologies if I've done the wrong thing by piggy backing the Not starting thread.

Fuel pump runs at ignition, battery has been on and off several times. The really strange thing is that I get a longer run if I activate the inertia switch, it seems to run longer until the fuel has gone, reprime the pump, it does the same thing. Reset the inertia switch and it feels like there is one round of firing, then dies off immediately.
No codes present using the jumper.

[riksit2000]

I always lean towards there is no such thing as a coincidence. I would Triple check cam belt timing and tension before digging a deeper rabbit hole, was the tension set at TDC or the correct way? How was the weight/pressure applied to the belt to obtain correct tension. I’ve done over two dozen timing belts on Lotus Esprit and M100 yet I somehow ma naged to mistime an Esprit recently (in my defence the dots on the cam pulley were wrongly oriented but I still have a lump where I smacked my head )

I'm absolutely (99% ) certain the timing belt is correct, as mentioned, the car started and ran really well after the change. I've since stripped and checked, all is good. I'm more concerned about what I could have moved/disturbed as I rebuilt it after the front bumper was off, I'm struggling to understand what. Started thinking about if the fuel pump could have an electrical issue? I'm doing some checking/monitoring today.
here is a link to a video of the difference in run time with inertia switch in the running position vs it tripped: https://youtu.be/ImIDXwgsj5s
Not quite sure as to what to make of it.

[Simon_P]

Have you checked that the ECU earth cables (3 wires) are properly secured to the plenum?

[dapinky]

Can one of the moderators or head honcho's (Dave, Geoff et al) please separate this into another thread otherwise it is going to get confusing

I think that all these posts belong to this one, and not the other one.....

[Rambo]

Looks good to me Dave. I thought it would get very confusing if we had 2 similar non starting issues under 1 post

Thanks for separating the respective problems

[Rambo]

Have you checked that the ECU earth cables (3 wires) are properly secured to the plenum?

And check any other earthing points whilst you're at it. Further info here.....http://wikilec.com/view/Electrical

[dapinky]

It makes sense to have them separate, but as there are clearly some similarities, they are best read in conjunction with each other.....

..... normally, when we get similar problems, the thread has been inactive for a while (and hopefully resolved), so it makes sense to resurrect an old one - not often we get such similar issues within days of each other.

[alan e]

Fuel pump runs at ignition, battery has been on and off several times. The really strange thing is that I get a longer run if I activate the inertia switch, it seems to run longer until the fuel has gone, reprime the pump, it does the same thing. Reset the inertia switch and it feels like there is one round of firing, then dies off immediately.
No codes present using the jumper.[/quote]

After it dies do you still have power at the fuel pump ?.

[riksit2000]

Fuel pump runs at ignition, battery has been on and off several times. The really strange thing is that I get a longer run if I activate the inertia switch, it seems to run longer until the fuel has gone, reprime the pump, it does the same thing. Reset the inertia switch and it feels like there is one round of firing, then dies off immediately.
No codes present using the jumper.

After it dies do you still have power at the fuel pump ?.[/quote]

Yes, I can hear it running.

[riksit2000]

https://youtu.be/ImIDXwgsj5s
Video of the running with and without the inertia switch tripped. Not sure what to make of it, engine runs longer with switch tripped.

[alan e]

https://youtu.be/ImIDXwgsj5s
Video of the running with and without the inertia switch tripped. Not sure what to make of it, engine runs longer with switch tripped.

Not able to watch it's coming up has private.

[Rambo]

Excuse my lack of electrical knowledge, but is it at all possible that someone has rewired the inertia switch at some time and changed the polarity ?

http://wikilec.com/images/e/e9/MJ25-05_Fuel_Pump.gif

[riksit2000]

https://youtu.be/ImIDXwgsj5s
Video of the running with and without the inertia switch tripped. Not sure what to make of it, engine runs longer with switch tripped.

Not able to watch it's coming up has private.

Changed to public now.

[Simon_P]

A similar thought to Rambo rule out the switch - attach a meter to the out terminal of the cutoff switch what is happening? do you still get volts when it dies?

Have you checked the engine earth?

You mention that it will run if you use the accelerator - Check that the IAC valve is plugged in properly if it is create a vacuum leak and see if it improves if it does create a bigger leak until it runs.

Check the MAP, MAT and TPS connections.

Do you have access to elanscan?

[alan e]

If you look at the wiring diagram the pump shares it's supply from the relay with a wire W/G 22G going to the ECM if that wire is disconnected at or to the ECM the pump will still run and its possible that the engine will not it's worth checking to see if you have 12volts on that wire at the ECM when the pump in running.

[riksit2000]

Excuse my lack of electrical knowledge, but is it at all possible that someone has rewired the inertia switch at some time and changed the polarity ?

http://wikilec.com/images/e/e9/MJ25-05_Fuel_Pump.gif

It's on a plug, so difficult to get wrong, I suspect.
I've owned the car for four years, trouble free, so no wiring mods made.
I've disconnected the feed to the fuel pump today, ran an independent supply direct from the battery, no success, still scratching my head.

[riksit2000]

If you look at the wiring diagram the pump shares it's supply from the relay with a wire W/G 22G going to the ECM if that wire is disconnected at or to the ECM the pump will still run and its possible that the engine will not it's worth checking to see if you have 12volts on that wire at the ECM when the pump in running.

That's a good call, I've been thinking that the signal may be getting there and causing a problem, maybe it's not getting there at all? One for tomorrow. Cheers.

[alan e]

Did you fix your not starting problem ?.