Engine turns but won't fire

[glynlucas]

I am tearing my hair out!! I installed a new battery and tested everything was fine after installing it.

A day later, come to the car and it will not start! Nearly started first turn, then nothing!
Engine turns over fine, but will not fire.

I Checked that the fuel relay comes on, checked all fuses ok, tested for a spark ok, can smell fuel after several cranks so fuel is getting in, checked connection to ECU, tune resister ok, - can't understand why it will not fire.

Any thoughts?

[GreenV8S]

Maybe it's just flooded. Whip the plugs out and either (ideally) replace with new, or clean with a wire brush before replacing. For extra brownie points warm them in a gas flame to burn any contamination off the surface, and refit while still warm.

Doe the rev counter move when the engine is cranking?

[glynlucas]

I wondered if it was possibly just flooded. What is the significance of the rev counter moving when it's cranking?

[Boosted LS1]

glynlucas said:

I wondered if it was possibly just flooded. What is the significance of the rev counter moving when it's cranking?

The tacho gets it's signal from the coil neg iirc. So I guess it tells you the coils doing something

Boosted.

[Bob the Planner]

I thought the tacho got its signal from the ECU, but could be mistaken. Snorky had the same symptoms on the Tiffin run which was cured (temporarily) by putting an ice pack on the coil as suggested in the bible. However, it turned out to b the ignition amplifier - see [url]here| www.pistonheads.com/gassing/topic.asp?f=8&h=&t=198059[/url].

[GreenV8S]

Boosted LS1 said:

The tacho gets it's signal from the coil neg iirc.

This gives a quick sanity test of the power to the coil, and the points/ignition module/wiring on the LT side. It doesn't prove you have a spark, but it's a start.

[glynlucas]

OK, tried leaving the car for 3 hours, checked that there is definately a good healthy spark at the plug and there is definately fuel reaching cylinders.

However, still seems totally dead!
I can only assume it's flooded!

Could the airflow meter be the problem?

[raw-sewedge]

Have you checked things like the output from the trottle pot?

There is a good sequence of diags here for the EFi.

[GreenV8S]

glynlucas said:

Could the airflow meter be the problem?

Anything's possible, but since you're getting fuel it seems unlikely. My guess is that it is simply flooded, as previously suggested. What are the plugs like?

[parrot of doom]

Its no good checking that the fuel pump relay comes on - I had a similar problem. Pull the entire loom into the footwell, and completely remove both silver relays. Check for corrosion on the pins. Then plug them back in. Make sure each and every pin is well and truly home (by wiggling the wires on the back of each socket).

Also, make sure there is a thin bit of carpet between the battery terminals and the loom when you put it all back in.

>> Edited by parrot of doom on Monday 29th August 22:24

[glynlucas]

Thanks for the suggestion guys...

I have to say, I don't understand why anything should have changed since it was running perfectly when I tested it immediately after replacing the battery.

I have taken out the loom in the footwell and checked all relays and fuses. All looks fine, no corrosion or ill-fitting connections. I suppose the best plan is just to put it on charge and try it again in the morning!
Thanks again for all the advise, I really appreciate your help.

[chim666]

parrot of doom said:

.... Pull the entire loom into the footwell, and completely remove both silver relays. Check for corrosion on the pins. Then plug them back in.

You say you have fuel delivery - it might be worth swapping the two silver relays over, if you can't hear the fuel pump anymore, there's you answer...a duff relay - next thing...find out which one is for the fuel pump !
Good luck.

[parrot of doom]

IIRC the blue one is for fuel, but I could be wrong.

They're only £6 each.


Anyhow, if you log on to the Bosch website at www.boschautoparts.co.uk/ and click 'service locator', then enter your postcode, it gives you a list of local suppliers.

The part number is Bosch 0332014112, and I just found a place near me that does them for £6 plus VAT. I'm going to get a couple more, replace the other relay (might as well), and keep the new and old ones spare in the boot.

[glynlucas]

OK, update on progress....
Car still refused to start this morning. Decided to go through the fault diagnosis as suggested and found that one of the Lambda sensor heators was faulty. I called local TVR garage and they said this would not cause the car to fail to start. So, suspecting the ECU, I was kindly loaned one to test... Still wouldn't fire!
Only one option, tow it to the garage for full diagnostic! Decided to try droping the clutch when towing and the car started without too much fuss but ran very roughly and would not keep running after a few minutes. It is now awaiting diagnostics at my local independant TVR garage!

He suspects the fuel pressure regulator....

I'll let you know what happens.

[v8 racing]

it could still be a set of sooted up plugs as mentioned earlier, espiecially if they are b7ecs's they are a great plug but once sooted they just wont reclean themselves.

[glynlucas]

Well,

I would be very happy if that was the case! I did take them out and clean them and run them over a gas hob for a couple of minutes before reinstalling them to no avail...

I'll keep you posted.

Thanks

[GreenV8S]

Is the vac line to the fuel pressure regulator still connected at both ends? Mine ran like a dog when this fell off.

[v8 racing]

honestly that wont work, you can clean as much as you like but they still wont have it!! i am not saying it is the plugs but for the sake of a few quid it has to be worth doing, i recomend a plug change every 5000 miles for an engine that gets used well half that if it is just going to the shops and back.