Never trust a French fuel gauge / Why my GTi won't start?

[Melchior]

Bought and fitted brand new dissy cap and rotor arm - problem still there

Still there and worse! I can now stall it by opening the throttle fully in neutral. It revs hard, then drops to 2500 or so, spluttering and popping, revs gradually dying. After a few secs it cuts out. Struggles a little to restart but does and idles fine. If I release the throttle during the spluttering stage, the revs drop to idle and it ticks over normally.

So I am convinced it's spark rather than fuel. It feels like it's running very very rich whilst my foot's on the floor but the fuel isn't igniting, hence why I think it's spark (or, lack of spark!).

I would happily rule the spark plugs and HT leads out. I would think if one were faulty, it would only misfire on one cylinder but this is across all 4. I already changed the main HT lead (king lead? From coil to dissy) so that's ruled out now too.

So that leaves coil or ignition module.

Yeah, about that ignition module and it's location, I know people have said it's under the inlet manifold but really I don't see it. I did find a module which looks like the thing, located behind the battery on the bulkhead on the left side of the car. Don't forget mine is LHD and I don't know if that would mean it gets a different location from you RHD chaps.

[RobC]

I did find a module which looks like the thing, located behind the battery on the bulkhead on the left side of the car. Don't forget mine is LHD and I don't know if that would mean it gets a different location from you RHD chaps.

That's where the module is on 16v models.

Does it look like this? https://www.google.co.uk/url?sa=i&rct=j ... 8776189845" onclick="window.open(this.href);return false;

If so that's a module.

NB that's not the correct part for your car... just an example photo!

[Melchior]

Yup it kinda looks like that example photo

I took a pic of it the other day, I'll try to get some time later at home to post it here.

What are the chances of that being at fault? Sure it's not unheard of for them to fail but... really??

I dunno the tech behind how a coil works but I've got a feeling that the way it will firstly rev very high and then die might be a clue. Does the coil store power at all? So for a brief moment it might have enough juice to provide that strong spark for the high revs and then lose it all, hence the dying out?

So so many questions - sorry for them all but I would much rather try to figure it out and then replace the part rather than replacing everything like a maniac and finding the problem still there (might end up that way though!!!)

[RobC]

As I said very early on in this thread - your symptoms are exactly the same as I had when my module failed. They DO fail, and they also demonstrate weird behaviour at specific revs. (For reasons my non-electrical-expert brain doesn't understand.)

Also, aftermarket ones (I tried a couple of 'Intermotor' modules) are crap. If you do replace it, make sure you get a real Bosch replacement.

Maybe it's not actually failed, maybe it's dodgy wiring in and around it (for example I once had a dodgy earth feed from my module as well and had to splice in a new one to the crappy wiring). But don't discount it.

[RobC]

PS you have checked the fuel filter too? They're a lot cheaper to replace than ignition modules...

[Melchior]

Not checked but I think that will be next as I am now on a train instead of in the car on my way home from work! Total failure to proceed 200m away from work thank good was there was a kind passer by to help me push the bx back to work car park.

Before this I did some revving with bonnet open and noticed a distinct lack of fuel pressure (by squeezing the feed pipe whilst revving) with throttle wide open and engine spluttering like mad. Let it idle and the pressure goes back up and the pipe is hard.

[MULLEY]

Could the fuel pulse damper be blocked?

[Melchior]

No idea Mulley. Never even heard of one of those before and Googling just brings up Mazda RX7 stuff!

New fuel filter bought this morning, brought a load of spanners to work with me and will attempt somehow to change it in the work car park later today. Thankfully I happen to have a pair of motorhome levelling ramps in the boot so should be able to raise the backside of the car up a bit to get at the filter. WHY they put it there instead of in the engine bay beggars belief!

I am assuming a couple of bolts to undo it but have no idea so far.

Old cars eh...?

[Melchior]

Finished work and went to the car to replace the fuel filter. Just for fun I tried to start it and to my surprise it fired right up. Thankfully I had the presence of mind to raise the suspension as after about 10 secs idling (with the K light lit) it just died. My foot was well away from the throttle pedal, it was idling pretty smoothly and then it just cut. No coughing or spluttering, just as if I'd turned the ign off.

This made me really think it must be an ign problem as IMO if it was fuel pressure/delivery it would have spluttered at least a bit before dying. Wouldn't restart.

Fuel filter replaced anyway, just in case. Won't start.

I now stink of petrol and have some advice. If it's cold and windy outside, do NOT get petrol on your hands. It gets VERY BLOODY COLD and hurts!!!!

My next step for tomorrow is to bring more tools to the office so I can pull a plug and 1) see what it looks like to give an idea of what's going on in there and 2) check for a spark when cranking. I'll bet there's none.

If no spark this means either:
1) ignition module
2) coil
3) ...?

I keep reading horror stories about shoddy wiring causing all manor of nasty problems and hope to goodness my problem isn't caused by a bad wire (somewhere?!) as I hate electrics and know it will take an absolute age to find out where the break might be.

So I hope it's 1 or 2 above. Or crank sensor. Or... well... what else could cause this?!!

Photo of it as it is right now. That's the Amsterdam area on the left side - it's Holland vs Romania tonight and the party appears to already have started. They blasted out Gangnam Style earlier...

[Melchior]

Took all plugs out and find there IS spark.
Cranked it over whilst plugs out. Normally I would expect to see whisps of petrol blasting out the open plug holes but there was nothing. Put my hands over the holes while my assistant cranked it over and felt/smelt no fuel.

Disconnected pipes to the fuel rail and cranked over - no fuel coming out.

I don't hear any fuel pump activity. Normally I would expect to hear it prime when you turn the ign on (although I never noticed that with the BX but did with other cars I've had) and deffo expect to hear it whilst cranking. The rear seats are up so I'd expect that would let me hear it.

So now I think the following:
1) pump dead (likelyhood...?)
2) pump fuse (blown caused by bad pump, would explain spluttery running and now total death)
3) pump relay (does it have one?)

Next question - where is the fuel pump fuse and relay? I don't find it in the fusebox under the dash (LHD).

[Way2go]

I don't think that there is a dedicated fuse for the fuel pump. The power is derived through the injector relays in conjunction with the ignition switch.

[Melchior]

Some say the pump should prime when turning ign on and some say it should only pump when cranking the starter :-/

[Melchior]

Hmm, we're getting a bit cross-threaded here:
http://www.bxclub.co.uk/forum/viewtopic.php?f=2&t=17886" onclick="window.open(this.href);return false;

General consensus seems to be that the pump only pumps whilst cranking the starter, once the engine fires the ECU continues to make the pump run.

[Melchior]

W00000T!!!! She started!!! And then died again.

One of my colleagues volunteered to help. I pulled up the passenger seat and carpet, found the yellow wire with white connector. Measured about 9-10 volts whilst cranking - great, fuel pump wire is working.

To the back of the car and I get the meter on the wires to the pump there. Crank it - great, still good voltage. But I can't really hear it running so I give the wires a bit of a fiddle while he cranks it. Then I hear something, very quiet though and she splutters into life! Joy!

She carried on running for a good few minutes until I disconnected the wire under the passenger seat (morbid curiosity). She spluttered and died and wouldn't restart after connecting the wire again. My assistant had left by that point so I couldn't repeat the same as earlier.

One of the two connectors on the pump is VERY rusted and messy. While the engine was running I could hear and feel the pump running but it was NOT constant. Seemed to be randomly going on and off - more off than on.

Next step - new pump...

[citsncycles]

Not an expert on fuel injection systems, but if the pump runs on pressure it may not run constantly anyway.

Would it be worth trying to clean up the rusty connection (or even replacing it) before bying a complete pump?