Gti-6 Won't Start

[mattg 3]

Here's a strange one... Miles is helping me out over PM but as i'm sure he's away racing at the weekend I thought i'd pop this up to see if anyone has any thoughts...

 

My 205 is running a GTI-6 (well, Xsara VTS lump)

 

It was running fine until it coughed once on the way home then cut out. Since then it is refusing to start and I had to be recovered. It turns over fine but won't fire.

 

First step was to change to crank sensor for a new one. No change.

 

Then I checked for 12V at the fuel pump when turning over but only had .1V I then bridged pins 5 and 8 on the fuel relay loom as advised on various forums to test the relay and was now getting 12v to the pump. So, I put a brand new relay in... now i'm back to 0.1v going to the fuel pump.

 

I'm completely stuck now, maybe the ECU is knackered? If I was getting 12v to the pump i'd suspect that but as i'm not I don't know what to test next really!

 

any thoughts?

 

Thanks in advance!

[cheesegrater 43 1 Cars]

What did you do with the inertia fuel shut off switch? Or wiring to it?

[mattg 3]

The conversion wasn't done by me but Pug Racing so I guess it would have been got rid of...

 

If it is still there, where would I find it?

[welshpug 1,626]

Between the fuel pump relay and the fuel pump! specifically within a foot or so of the relay, near the rear of the battery

[mattg 3]

Thanks mate, will see what I can find....

[mattg 3]

Looks like its been deleted as I can't see anything at all tracing the wires...

 

I guess that leaves the ECU?

[welshpug 1,626]

Or the ignition switched live.

 

check you have switched 12v+ at pin 14, and permanent 12v+ at 2,11, 8 and 15

[mattg 3]

Or the ignition switched live.

 

check you have switched 12v+ at pin 14, and permanent 12v+ at 2,11, 8 and 15

 

Thanks for this Welshpug... Just been and checked and I have exactly what you say I should above.

[welshpug 1,626]

ok, in which case you should have 12v to the injectors and coils with the ignition on.

[mattg 3]

ok, in which case you should have 12v to the injectors and coils with the ignition on.

Aha, here we go... I have neither.

[mattg 3]

I guess this points to an ECU issue, do you think it's somehow re-locked itself or just died?

[S@m 156]

Does it not point to a double relay issue? Since the pins on the double relay plug are getting the correct voltages but then not getting any further.

[mattg 3]

It does... Alas I've already replaced that with a brand new one. Then again, I could be really unlucky and the brand new one is dodgy. Miles has kindly offered to put my ECU on one of his cars to find out if it's any good or not... At least I'll know for sure then.

[mattg 3]

Well, this is frustrating... My ECU is working, it starts the car that Miles has tested it on.

 

The double relay is brand new

The crank sensor is brand new.

 

Miles is sending up a known good relay and crank sensor for me to borrow for test purposes but if this doesn't do it i'm stumped!

 

I know from the forum that bridging pins 5 and 8 on the relay give power to the fuel pump but is it possible to bridge the pins to give me ignition also to enable me to see if it will start? If so, does anyone know which pins to bridge?

 

appreciate everybody's input so far. I'll be sure to update with what actually sorts it for search purposes.

Edited June 14, 2013 by mattg

[Toddy 7]

1)Check resistance of crank sensor + good connection , if the ECU doesnt see an input from the crank sensor then the coil and injectors will not fire/pulse.

 

2) Check that the coil and injectors have 12V feed with the ignition on, how exactly have you tested this? these items are switched earths, therefore you cant use the negative pin on the plug you are testing.

 

3) If you have 12V at coil or injectors - Buy a 12V diode from maplin etc, insert this in the coil or injector wiring plug (the diode will only allow current to flow in one direction). Crank the engine and the diode should flash repeatedly. If not I would suspect crank sensor, after check wiring continuity.

 

4) When bridging pins 5 & 8 on the double relay with the ignition on you should have the fuel pump running continous.

[mattg 3]

Thanks for the input on this Toddy. Answers as below...

 

1)Check resistance of crank sensor + good connection , if the ECU doesnt see an input from the crank sensor then the coil and injectors will not fire/pulse.

I've done the test on this. Both old and new crank sensors are good.

2) Check that the coil and injectors have 12V feed with the ignition on, how exactly have you tested this? these items are switched earths, therefore you cant use the negative pin on the plug you are testing.

This is great input. I didn't realise the switched earth bit, I thought you could test on the pins. How should I test this properly?

3) If you have 12V at coil or injectors - Buy a 12V diode from maplin etc, insert this in the coil or injector wiring plug (the diode will only allow current to flow in one direction). Crank the engine and the diode should flash repeatedly. If not I would suspect crank sensor, after check wiring continuity.

OK, will give the LED test a try.

4) When bridging pins 5 & 8 on the double relay with the ignition on you should have the fuel pump running continous.

Yes, when bridged the pump gets the full 12v

[Alastairh 47]

If you get stuck i can pop over and take a look, i have a few spares also.

 

Al

[mattg 3]

Appreciate it Al, there's a strong chance I'll take you up on that! . Are you the Al I bought my manifold from by the way?

Edited June 14, 2013 by mattg

[Toddy 7]

For checking the 12V supply at the coil/injector the positive multimeter probe goes into the electrical connector positive supply ( can't remember whether this is pin 1 or 2 but no damage will be caused,so process of elimination)& the negative probe can be any grounded surface, earthing point etc, easiest place will be battery negative terminal.

 

Just be careful and don't touch the positive battery terminal with the probe when the other is connected to the loom.

 

Al H will sort you out.

[mattg 3]

Thanks Toddy, will give it a go once my ECU gets back

[mattg 3]

Just to keep this updated incase anyone has similar issues and is waiting for an outcome. Got my now known good ECU back today and a known good relay... both fitted. No change.

 

Alastairh has kindly offered to pop over and help check through a few bits with me next week one evening. I'll be checking the things Toddy mentioned tomorrow to see if that yields any info.

 

Will keep this updated.

[mattg 3]

Update time. I've been on holidays so just got back and still determined to sort this. Al H was going to pop over an help me but unfortunateley I can no longer raise him so I'll have to draw a line under that

 

I fitted my known good ECU which Miles tested on his 306 and a known good relay that Miles kindly lent me from a spare 306 which ran and checked the voltages again. (obviously I tried to start it again, ever hopeful it would go but it didn't) This time though, I followed Toddys advice so I knew I was measuring correctly.

 

I get 0.1V at the injectors and between .08v and .1v at the fuel pump while cranking so clearly it's not getting what it should...

 

The last thing I can think of is the brand new crank sensor is goosed but i'm getting the expected results using the multimeter over the pins as per the guide on this site.

 

I think i'm going to have to send it back down to Miles to work his magic as it's going to be in my garage for evermore at this rate unless anyone can think of anything else.

 

As always, thanks for the input so far.

[Anthony 1,000]

Does the fuel pump prime at ignition on? If not, it's likely to be something fairly fundemental and not a sensor issue.

 

Are you absolutely sure that you have the correct switched and permenant voltages at the relay socket, and that you've a good ECU loom earth?

 

If the ECU and relay are known good then, assuming the pump doesn't prime, it has to suggest that it's something relating to the wiring.

[mattg 3]

Does the fuel pump prime at ignition on? If not, it's likely to be something fairly fundemental and not a sensor issue.

 

Are you absolutely sure that you have the correct switched and permenant voltages at the relay socket, and that you've a good ECU loom earth?

 

If the ECU and relay are known good then, assuming the pump doesn't prime, it has to suggest that it's something relating to the wiring.

 

 

Thanks Anthony, good point, no the pump doesn't prime on ignition on. Infact it gets zero volts when the key is turned to lights on, going up to a max of 1v when the engine is turned over.

 

Earths all seem good.

 

Like you say, it does sound like a wiring problem of some sort. Odd that it was fine for 200 miles then just died though.

[Anthony 1,000]

If the pump doesn't prime, ignore all the sensors as it's something more basic than that, and as said, with the ECU and relay proven it almost certainly has to be wiring related.

 

Firstly, go back and double check the voltages at the relay socket, both with ignition on and ignition off. I can't remember the pins off the top of my head (a search will reveal them) but you should have a mixture of constant 12v and ignition switched 12v spread over around five pins off the top of my head.

 

Find the pin out for the ECU plug (eg from Autodata) and do a resistance check between the earth pin(s) and the battery negative terminal - it should be 0 ohms. Whilst there, double check that you've got 12v to the pin(s) that supply the ECU with power.

 

If they're both good, double check the whole loom for anywhere that it might have got chaffed or burnt, and in particular double check where the GTi-6 and 205 looms have been spliced together, as often these joins are utterly dreadful on some looms that I've seen, made presumably by an ape armed with nothing more than a banana (see also "professional alarm installers")

 

That it's successfully done 200 miles suggests that it was certainly wired up correctly initially, but that something has got damaged or broken, and that could easily be a wire inside the loom hidden from view. Take comfort in the fact that you've got a hard fault though, as they're sooo much easier to diagnose than similar issues that only occur intermittently or under a rare, specific set of circumstances!

 

PS. The current low (sub 1v) voltages that you're seeing can be disregarded as they're effectively "noise" for use of a better term. It will be a very clear voltage when you get a reading, probably around 9-10v under cranking and should be around 12-13v otherwise.

 

PPS. When testing for voltages, make sure that you're checking against a good, clean earth!