New Build - Engine doesn't start

[cb4798]

Hi All,

I am 95% of the way through a new build and the post title says it all really. I have (as far as I can tell), put all the wires in the right places. The engine has a very healthy turns over and gets oil pressure but it won't fire. First, I checked the fuel line and judging by the amount of fuel that sprayed over me when I disconnected the fuel line, that it isn't the problem. I then tested a spark plug and it doesn't seem to be sparking. I have kind of reached the end of my ability to debug this issue.

Any thoughts on how to proceed appreciated.

by the way it's a sigma 140

Chris

 

[OliW]

Is the inertia switch pressed down?

[OliW]

Sorry.  Hello...how rude of me!

[cb4798]

Hi OliW, Yeah, the inertia switch is pressed down.

 

[SM25T]

Is the immobiliser disarmed ?

[Jonathan Kay]

After those two:

1. What sort of dash?
2. Do you have a kill/ master switch? 
3. Check ECU and other relevant fuses.
4. Check that all sensors and similar are connected.

Jonathan

[cb4798]

I pretty sure its not the immobiliser. I can hear it click and the light appears to do everything correctly.

[cb4798]

Hi Jonathan, Its the standard supersport dash, which i believe is just a standard dash.

No kill switch.

I checked all the fuses and they look ok.

I have pushed in everything that I can see, but there aren't that many connections.

[John Vine]

Sorry to hear of your problems -- not what you want so close to completion!  I'm not familiar with the Sigma, but here are a couple of thoughts...

Is the crank position sensor connected OK?

Do all other electrical items (lights, fan etc) work OK?

JV

[cb4798]

Hi John,

 

Tell me about it! I really don't want it to go back to caterham without starting it. It's starting to put a bit of a damper on the experience.

 

I'm not sure which sensor is the crank position sensor - can you enlighten me?

 

Lights, horn, heater etc all work.

[DJ.]

The crank position sensor is low down on the engine block at the back under the starter on the Sigma engine.

Duncan

By the way the immobilizer would stop it turning over.

[mikecocker]

Check that the three engine loom to chassis loom plugs are connected correctly and make sure the coil plug at the rear of the engine is pushed fully home. Also check the group of earths from engine that bolt to bulkhead.

[pugwash]

Chris,  I feel your frustration.  Pressing the big red button for the first time was one of the highlights of my build.  Sorry yours has not got there quite yet....but it will!

Lots of good ideas above.  You could unplug the two cables from the inertia switch and bridge them to check if you have a faulty switch (or just put a meter across the switch to test it).

Not sure if you still have to disassemble the mail ECU plug to fit the wire for the change up light but can't do any harm to unplug and then replug the ECU just to make sure all the pins are fully seated.

To unimmobilise my immobiliser I do need to push the little fob upwards slightly so the it is close enough to the sensor aerial, others have loosened it so it dangles down a bit.  But if your dashboard light is doing what it is supposed to then that cannot be it.

Hope you crack it soon!

 

 

 

[cb4798]

Thanks all. I will have ago at the above suggestions.

Interestingly, when I spoke to Caterham about the immobiliser, they suggested that when it is all connected up for the first time, the car can turnover without it being unimmobilised - a bit wierd! Anyway, I do have to move the fob side to the ignition barrel for it to work, so I think I can discount that.

If the car isn't earthed properly, would it still turnover?

 

[AndrewB]

Did I read something once about needing to have a certain amount of fuel in the tank?  How much did you put in the tank?

[AndrewB]

Silly question sorry but is the battery fully charged ?

[cb4798]

Hi Andrew,

The guide says 15 litres. I put in 17 to make sure. I even double checked the receipt to make sure I didn't buy diesel like i'm used to.

I think we're into the silly question stage now, which is fine by me.I'm convinced it's something i've missed. The battery is charged.

Chris

[Bio]

If you have fuel and it turns over but no spark, either the ECU is not telling it to spark .....Check that the correct plug is connected to the crank sensor or the coil pack has no voltage.

If it has fuel and a spark it should try to run.

Good luck.   

 

[Martin J]

I had exactly the same scenairo with my sigma build.  Check the quality of the earth that feeds the ECU. I had to drill another hole near the battery, remove a little powder coating & bolt the bugger down tight. Then it started. 

[Jonathan Kay]

Bad ECU earth would explain nicely. (I didn't know it happened in practice.)

Jonathan

[ChrisC]

Do you know someone local who has the lead to plug it into a laptop to see what's going on?   I am in Essex if that helps.

 

[billyboanerges]

I've known a similar case.

The problem was a bent pin on the ECU connection!

Good luck.

Tony

[cb4798]

ChrisC, what software/lead do I need? I'm happy to invest in it. Essex is probably a bit far, but, thanks for the offer.

 

[Alan Bowler]

Sometimes just a second pair of eyes is needed. Where abouts are you? There might be a local member nearby who can take a look.

[Crank position sensor or not quite 100% battery get my vote]

[diggerman]

On the qustion of enough fuel or not, when you switch the ignition on, you should hear the fuel pump (which is in the fuel tank) run for about a second. If it does that and stops you have enough fuel. Otherwise you need more fuel. I cant remember how much fuel I put in at first start up, but it was a considerable amount, and it wouldnt start until I had been very generous!

peter