Intermittent Starting - PLEASE can someone help me!?

[malcster]

Hi Guys, PLEASE can someone help me!?

I seem to have a bit of an intermittent starting fault, which has caused my MR2 Turbo to be abandoned a few times

Basically I turn the key, it turns over, but doesn't fire into life.
It would seem leaving it over night and going back to it allows it to start again.

I have changed:
- Distributor Cap & Arm
- HT Leads & Spark Plugs
- Coil & Igniter
- AFM cleaned - flapper door is moving freely
- Clifford alarm / Immobiliser all checked, no problems
- ECU water temp sensor
- Changed 2 relays in the engine-bay fuse box: The one marked IGN (Kinda light green in colour), and the one marked EFI (silver round one).

It was ok for about a month after changing the relays, and then low and behold, I switched it of in Aberdeen, left it for 5 mins, went to try and start it, and nothing. Now it's been abandoned up there!

This is costing me an arm and a leg having to get trains home, and back out to it again each time!
It usually seems to fire into life again, after going back to it though.

No error codes are held etc.

Any ideas what could be up?

[dawesy]

have you changed the cold start switch? (grey sensor on the water elbow IIRC) could be its busted and when the engine cools down just a bit it fires up the cold start injector which can foul the plugs.

[g.lewarne]

fuel pump iteslf, fuel pump relay or blocked fuel filter at a guess.

next time it wont start, open the diagnostics port cover, and place a wire bridge between B+ and FP this will make the fuel pump run constantly when ignition is on - you should be able to hear a gentle whine from it around the gear lever area if its working (turn off all fans, radio etc as its very quiet)

[malcster]

Thanks for th suggestions guys,

have you changed the cold start switch? (grey sensor on the water elbow IIRC) could be its busted and when the engine cools down just a bit it fires up the cold start injector which can foul the plugs.

I haven't changed the cold start switch or the cold start injector.
I'm not sure it's a fouling thing, I would maybe expect more of a stutter when it tried to start, but there's just nothing?

fuel pump iteslf, fuel pump relay or blocked fuel filter at a guess.

I haven't investigated fueling yet.

Someone told me that the igniter actually cuts fuel from the engine if it thinks there might be an issue with it not getting a spark - to prevent the engine flooding. Is this true?

I have tried a 2nd hand igniter & coil pack (but obviously don't know the quality since it's 2nd hand) I'd be pretty unlucky to have had 2 dodgy igniters though I guess.

Thanks for this tip to bridge B+ and FP, I will try this next time!

Fuel pump relay is the black box on the rear bulk head isn't it?
I noticed the bracket holding it on was a little corroded - is this an earth?

Should I be able to feel the Fuel Pump Relay clicking (if I had my finger on it) each time I get someone else to turn the ignition on?
Or will this only click on if there's no pressure?

Also, what about whipping a plug out when it won;t start, should it be wet with fuel? Should I be able to smell fuel strongly? As I haven't check this this when I had the plug out - though I know I am deffo getting a spark...

[dawesy]

would be worth removing a plug to see if its wet, might help diagnose if you are getting fuel or not.
tricky one this as it appears from what you've said its fine from cold