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Non starter - injector relay problem?

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  • [Corsa C 2000-2006] Non starter - injector relay problem?


    I'm a new Corsa owner and new to the forum.

    I bought a Corsa C about 4 months ago and it's not been very good. It's a second car which I bought for work and as a result of the problems I've only used it twice!

    It's a 2004 1.3 CDTI

    So when I first got it it took some cranking to get started. I noticed that the fuel pump in the tank didn't always seem to prime with the first turn of the key, however that didn't seem related as sometimes it would start without a noticeable prime, other times it would prime but not start.

    So I used it for work twice and both times flattened the battery trying to get it started on the return journey. I gave it to a local back street garage who are good but slow. He had the car for a couple of months and couldn't sort it. To be honest, I don't think this automatically means its a big thing, he was just very busy.

    When I got it back I tried starting it a few times, usually it would start but usually after some cranking - 10 seconds or so, now it won't start at all.

    I've been doing some tests on it today and found that the relay to the (primary) fuel pump is only receiving about 10 volts, it doesn't seem to be sufficient to make the relay switch. I stood right by it and it wasn't clicking. So I jumped the terminals to the fuel pump and that fired it up. I cranked the car with the fuel pump running but no luck.

    Next I removed the fuel line to one of the injectors, nothing came out on cranking with the key but with the starter off and again jumping the relay fuel came flying out at a rate of knots. I've also testing the relay with 12 volts and it works fine.

    I therefore conclude that there is nothing wrong with the primary fuel pump or fuel filter. I guess what ever should be telling this relay to switch is therefore also failing to tell something else to start. I presume this must be in the injector system. Having read around various forums I can't see any further advice.

    I assume it's not crank shaft sensor which I keep seeing come up as it runs well when it starts. Could I be wrong? That said it does seem to run quite rich.

    I have been reading about fuel injector relay but not very much detail anywhere. Does anyone have any knowledge and advice about how to test the function of the injector system?

    Many thanks,

  • #2
    Those FIAT engines are a pain in the neck. OK - when they a new they are economical, but they have a horrible flat spot and by 65k they generally start giving problems. And when they go wrong they get expensive very quickly.

    There's a range of things it could be, but the first thing I'd check is the state of the battery. At rest it ought to be around 12.5v, anything less and there's a dead cell which means the electronics aren't getting the right current. If the battery is anything below par those things won't start.

    If the battery is OK then the next thing to check on them is the ECU, make sure the connectors on it are clean with no sign of damp or corrosion.
    1972 Viva restoration thread -


    • #3
      Thanks for the advice. I've had it on jump leads and fully charged the battery a few times. I think the battery is original though therefore almost 10 years old. I'll check the voltage when cranking today.

      For the ecu where do I find it and how do I open it to check? I guess there's a thread somewhere that I should look for.


      • #4
        So I've had the battery on charge, again, and it's obviously goosed as it's barely trying to turn the car over now. With a spare battery also jumped the battery is measuring ~9.5 volts whilst cranking. I know it will drop from 12 volts under load, but this seems a little. It obviously needs a new battery so I'll pick one up and try again.

        Any further advice on where to find the ECU and how to check it's soldering. I'm sure there is probably a thread on it as it seems common, however when I was searching I struggled finding info on this engine. Indeed when trying to figure out which fuse and relay I needed to be looking at 20+ minutes on google still didn't find me info on a fuse box the same as mine. I found one similar in that it had the some but more. I could only find relay listing for that though. I ended up pulling all the fuses to check them!!


        • #5
          It does sound like the battery to be honest. It shouldn't drop to that degree on cranking.

          The ECU on those is in the water drain under the windscreen - which is why they suffer so much with moisture problems.

          Do one thing at a time, battery first, if that solves it then leave the ECU alone.
          1972 Viva restoration thread -


          • #6
            OK so I've ordered one on Eurocarparts (up to) 55% of discount sale. (They are getting a little bit like a sofa company aren't they!!)

            I'll hopefully manage to pick it up on the way home and try tonight.

            I'm very encouraged with the "It does sound like the battery to be honest" statement about. I'll be really pleased and at the same time quite dissapointed that I didn't do it months ago!

            I must admit though that I'm dubious due to the fact that the car hasn't been trying to 'fire' the last week or so even with jump leads from a donor vehicle.

            Fingers crossed eh!


            • #7
              Diesels need a hefty current to turn them over to fire, and the electronics will do all sorts of silly things once battery voltage drops. An old battery that is dropping voltage on cranking isn't going to do you any favours. Get a good quality battery with a high cranking ability, you need it on diesels.

              Jump leads won't carry enough current to fire up a diesel that's struggling. They only assist the car's own battery to an extent. Most people simply connect them and try to start thinking that the donor battery will power the dead car, it won't. It needs 10-15 minutes idle to boost the car's own battery before attempting to fire up.
              1972 Viva restoration thread -


              • #8
                So I tried the new battery and it's not solved the problem. It has helped but not cured.

                The battery I've bought it the one that Eurocarparts website said my car needs after putting the numberplate in. However on taking the old one out I see that it's a little bit smaller than the original. I guess it should be ok though particularly as it's brand new. The new one is 52AH 460CCA whereas the one I've taken off is 60AH.

                So on cranking this time, once again the fuel pump didn't fire up at position 2, then the car wouldn't start. On cranking however the voltage only dropped to about 11 volts.

                Frustrated with it I decided to jump the fuel pump again to see whether there might be 2 problems, the battery being one and something with the signal to the fuel pump relay being another. Still nothing. With the fuel pump running for several seconds before trying to crank and during cranking there was still no firing.

                Since we know that the fuel rail has fuel then the problem must be with the signal to the injectors.

                I guess I need to figure out exactly where the ECU is then and also how to check it's soldering.

                I did feel like I could hear hissing around the fuel lines with the pump running so I set about it with a stethascope. The hissing had finished by the time I found the stethascope though, I think it was coming from the lines around whatever it is at the end of the cam - I guess that's the high pressure pump? Listening to the lines however one line into or out of (sorry I don't know which is which) is quite loud, maybe that's just the sound of the pump though transfered through the fuel line rather than air.


                • #9
                  That battery is at the low end of what you need for yours. I'd have gone bigger. If you look around you're usually in the 70+Ah region.

                  If it's dropping to 11v on cranking was it fully charged when you got it? It should have been, but ECP are pretty rubbish.

                  Also - I can't remember if you've checked the injector relay or not. But again - a voltage drop play havoc with the system so the first thing is to make sure your battery isn't dropping volts on cranking.
                  1972 Viva restoration thread -


                  • #10
                    I'm not sure whether it was fully charged. I can charge it and see what happens. I was quite pleased with 11 volts though, I assumed that would be reasonable under load? Am I wrong?

                    Which is the injector relay? If its the red one below then yes it does work under test on the bench, whether its clicking in the car is another matter. I can put my meter on that and see whether it's getting a signal.

                    Oh - it looks like it won't let me post a picture, erm, the one I was trying to point out is the one that's directly to the (left) side of the fuel pump relay. It's the same size etc. and is actually marked ECU relay in the photo I was trying to attach.


                    • #11


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                        • #13
                          So I've bought a new used ecu kit off eBay for little money. I'm going to fit it and see what happens. If the problems cured then perhaps I'll have mine fixed properly. If no improvement I'll resell the kit. I've taken out the clocks and transponder. Just struggling finding the ecu and the other bit are. Not much info on net. I've took the scuttle and battery out. Can't get the cover off that box I think it's in though. Took 4 screws out but it's stuck. Not got the new bits yet ether so it's harder to know what I'm looking for!!!


                          • #14
                            Found the other 3 screws that I'd missed in the black box. What I understand to be the BCU is therefore free now. Just need to find the ecu. Looking at the photo of the one I've bought it looks like its open to the environment somewhere. I'll have another look tonight.

                            I've revealed the transponder but that doesn't seem to want to come off easily. Does it have a screw somewhere that I'm missing or does it just clip off with a little more force?


                            • #15
                              So my new second hand ECU turned up today (Sunday?). Apparently Hermes have a backlog and are delivering on a sunday too.

                              Now that I've got an ECU I've found mine easily, as I know what I'm looking for.

                              Swapped all the bits and its started. I've not took it out yet as all the bits are hanging off. In fact I've just finished off under the bonnet and finished for the night. I've got to put all the inside back tomorrow but that might take a while longer as I want to change the radio for a proper Vauxhall one which I've already bought. Also there's a car kit that I want to remove.

                              Once that's done I'll start using it and see whether it's reliable.

                              The fuel pump in the tank fires up straight away with the turn of the key which it didn't before. There sounds to be air in the line though.

                              According to the eBay advert the ECU I've bought has been re-mapped to 100 bhp from 70. So there might be a bonus in this too!

                              If and when I'm happy that the problem is cured then I'll decide whether to have my ECU fixed to it's good as new rather than another old one ready to die or whether to have the mileage changed on this one, as it's gained 40k miles today!