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Car won't start - Give me a check list
bi22le - 18/10/23 at 11:07 PM

This stuff always happens when you don't need it!

I have been doing the odd bit on the striker so may have knocked a sensor but now it just won't start. It has an OMEX 600 and I have the software so can read it.

Turn over is fast enough but it is not firing. Absolutely nothing. It's most likely got fuel, but if nothing it would at least for for once on fumes.

I hadn't checked for a spark but if it has fuel then it's not sparking.

Nothing obvious on the ECU software. All the sensors seem to be giving a reading.

Current thinking it's the crank trigger wheel sensor. I did remove it as I had to take the sump off. OMEX SW says I'm only doing 100rpm when cranking but I bet I am doing more like 800. Could this be the issue, no spark because it doesn't think it's cranking fast enough?

Are there any tools to use on the OMEX SW?

What else should I check?


falcor75 - 19/10/23 at 04:26 AM

Can you hear the fuel pump prime when you turn the key? Does the pump run when you crank the engine?
Of not check power to pump/pump relay and go from there.

If the pump primes and runs, check spark. If you have both fuel to the fuel rail and spark and it still doesnt start then check battery voltage when cranking. It could be that the battery has enough to turn the starter but not enough juice to power the ecu and ancillaries at the same time.
The starter will draw what it wants and the ecu will have to suffice with the leftovers, and if there isnt any spare voltage then the ecu wont power up/have enough power to energize the coil/s.

Alot of ecu's want to see minimum 300-400 rpm to start so again it could point to a weak battery.

[Edited on 1 by falcor75]


scudderfish - 19/10/23 at 05:47 AM

quote:

It's most likely got fuel, but if nothing it would at least for for once on fumes. I hadn't checked for a spark but if it has fuel then it's not sparking.



Don't make assumptions, check.


jacko - 19/10/23 at 08:36 AM

Nothing daft like a master switch turned off or a fuel pump switch


JMW - 19/10/23 at 08:52 AM

Can you get at the trigger wheel sensor gap to measure with a feeler gauge? If so, what is it? I was told my Omex 500 setup needs a gap of between 0.4 and 0.5 millimetres, and I take infinite care to get that every time I disturb the sump.

BTW Beware the influence of the sensor magnet on the "feel" using metal feeler gauges.


gremlin1234 - 19/10/23 at 09:12 AM

you should be able to find if it is fuel or spark, using a quick squirt of 'easy start'.

(but it is possible for 'easy start' to fire with just compression.)


Mr Whippy - 19/10/23 at 11:21 AM

smell the tailpipe for fuel, put a spare spark plug on top of the engine connected and check for spark


Schrodinger - 19/10/23 at 12:06 PM

Have you disturbed the earth to the engine? It should be ok as the engine is turning over but that might be because it is earthing through the throttle cable.


Slater - 19/10/23 at 05:24 PM

do you have a fuel shut off switch? the type that shut off the the fuel pump after a collision, maybe you triggered that somehow, they have a reset button on top.


Prof_Cook - 19/10/23 at 07:58 PM

Immobilizer/Alarm
Any blown fuses in the fuse box?


ReMan - 20/10/23 at 12:49 AM

quote:
Originally posted by Mr Whippy
smell the tailpipe for fuel, put a spare spark plug on top of the engine connected and check for spark

This
but I'dd add pull a plug out and check its wet with fuel
If dry why? Try easy start or even a slash of fuel in the cylinder and see if it fires
If no spark why?, is it all 4?
Sadly as you've already listed many possibilites with regard to tech and spark your going to have to do some metering/connection checking/parts swapping


bi22le - 21/10/23 at 02:51 PM

Thanks all, I did read your check points and they were all good a valid. I have been crazy busy at work since my OP but I had a few hours out in the garage this afternoon. This is how it went.

Tried to start it optimistically hoping it had fixed it self.

Checked battery voltage under cranking and fuses.

Fuel pump primes.

Removed spark plug - it was dry and not sparking.

Checked back at the trigger wheels as this is pretty much the only which can affect both fuel and spark, it's also the only thing I have really touched.

Unscrewed the timing wheel hall sensor from its mount and the mount itself, cleaned up all of the mating surfaces to make sure it was sitting correctly and close enough. Refitted nice and tight

Started first time on the button.

JMW wins the virtual hug. Your comment made me think it was definitely something to look extra close at.

Thanks all.

I'm at Northampton Motorsport next week for a full set up. I'll try and write up a post on here of how it went.

Fingers crossed it doesn't go pop.


JMW - 21/10/23 at 04:44 PM

Cheers, always a good feeling when you finally get it to start isn't it.