Advice needed - high emissions , central locking , fuel pump

[200OOM]

Hi, looking for a bit of guidance

Had the MOT today, and it failed on emmissions. I thought it would as it set of the carbon monoxide sensor in the garage this morning.

Before the MOT I have had a few electrical problems.

Fuel pump relay clattering and not engaging fuel pump. - I installed a new relay as described in previous posts . So the fuel pump is always running, as opossed to priming when the key is turned .

Then i noticed the central locking light lit. With the engine running and the doors closed if I pressed the button the engine stopped , and can be restarted usually. If the dors are open pushing the button has no effect .

Are the 2 related? Could the fuel pump running all the time cause over fuelling and high emmissions?

The car is a 1994 4lt, with key opening behind the doors. By inserting the key half way or so and turning it would lock and arm the alarm and immobiliser I presumed. Now it won't do this .

I have the dash top off , to see if any wires are shorting etc, but I don't appear to have a fox-guard alarm box , only a big black central locking box. Should I have the alarm box where I think it should be?

If I were to unplug the central locking would it do any harm? I only ask as if it's all central locking related I will just get rid of it.

Please help, the weathers getting good again.

[200OOM]

Thanks for the reply, I am the second owner and have had it for 15 years, never a problem before , so thinking something has just deteriorated ? If I remove the central locking module the car won't start. But there is a separate twin wire plug on the same module , if this is disconnected the car will run, and although the central locking light is lit , pressing It doesn't stop the car as previously said!!??

What does my immobiliser look like? Can it be by passed , if so could someone PM me with how to.

[200OOM]

hello, Its all worked from the keys. No fob or stick thing. I have deactivated the door solenoids. And I have never really locked it. I have also removed the black box under the back of the arm rest. I am basically looking to try and remove anything to do with the central locking, immobiliser or alarm. Once sorted I will get something retro fitted. Just need advise on what to remove and how to bypass .

[200OOM]

Hi, The fuel pump relay, the one with the 5 prongs, was continuously clattering. so after a bit or searching on the forum I have removed this relay and wired in the fuel pump directly via a standard 4 pin relay. The only difference being that the pump is running continuously from when the ignition is switched on, previously it would just prime, then run once the engine is running. With the new set up is there a possibility of over fuelling? When in its standard set up is the speed of the pump regulated at all , or is it just running flat out all the time? I would like to get back to the standard set up, but without the alarm, immobiliser and central locking.

[200OOM]

Ah, did not think about the Lambda sensors. that would confuse the system. So how do I effectively power the lambda sensors?? is it a permanent live when ignition on? what part of the original fuel pump relay housing do I need to get power to?? I think we may be getting somewhere.

[200OOM]

That's a great help, it has told me that the heating of the probe / sensor is controlled from the fuel pump relay. Since I have removed the relay its not getting any voltage, so not giving any readout , thus giving high emission readings, Will splice in a 12v supply triggered by ignition on. Thanks for your pointers on this. much appreciated. will update once done.

Thanks

[200OOM]

Hi, My fuel relay was clattering, so I replaced it with the same results. so I by passed it and via a new relay powered the fuel pump. but I believe by doing this I have removed the 12v to the Lambda's. Would everything not work if I put a switched 12v to the lambdas down the same wire from the old relay socket?

[200OOM]

Ok, I have a multi meter . What do I need to do? Switch to volts. Red probe on the terminals black to earth. What should I see from the 5 terminals . Really would like it back to standard. Will post the results once done. I feel progress is being made. Thanks for all your help .

[200OOM]

Ok.

Black probe to 86, red probe to 85. Ign switch on. 12.5v for approx 1 sec, then down to 0.

I also tried the black probe on a good earth and got 12,5v but constant?

Battery is good , hooked up to trickle solar .

What's next please Steve , the relay when returned has stopped clattering

[200OOM]

Also , ign on. Probe to good earth
87 shows 0.01v
87 below shows 0.01
86 0v
85 12.3v
30 shows 9.87v

[200OOM]

Also , ign on. Probe to good earth
87 shows 0.01v
87 below shows 0.01
86 0v
85 12.3v
30 shows 9.87v

[200OOM]

With the relay in I am not getting the fuel pump priming . Would the fuse be in the main board? Location if you know would be a help. So basically shake the wires and see if readings move . The try and narrow it down ?

[200OOM]

Hi, thanks for the wiring diagram , helps put things in the right place in my head.

I will check that fuse, but if I were to put 12v , switched , to pin 30 would that not sort the problem out of getting the fuel pump working and getting the lambda sensors powered again, assuming that they do get power from the fuel pump relay, that middle 5th pin?

I have the combined central locking and alarm box M0462 f

Would it just be a replacement part, plug and play as you say??

I have keys to open the door, and set the alarm

[200OOM]

Ok, so check that fuse mentioned previously, then cut the wire to pin 30, splice in a 12v switched supply. This should then give a prime to the fuel pump, power the lambda sensors and then run the fuel,pump once the engine is started? So basically as it was but with an alternative 12v supply to pin 30

[200OOM]

Thanks guys, The central locking box I believe is also the alarm. So would also presume it to be the immobiliser also. Will get the power to pin 30 and let you know, what happens. Will that also power the lambda sensors, which will then sort the emmissions out?

[200OOM]

For what ever reason putting 12v in did not work , possibly down to battery now flat. Will charge and resume . What I have noticed is the thick purple wire that should have been giving 12v constant when switched is giving 12v when ign off, then down to 9v when ign on. Where I that purple wire from . May need to tackle the rats nest of wiring . Why would the voltage drop ? I am thinking now to put a standard relay on fed directly from the battery, switched by a 12v supply , ign on, and then having 2 cables out to the fuel pump and the lambda heating circuit ??? This is how I had it running before , but with out the Lambda circuit being connected . So with 12v to the lambda I should get feed back to ECU to control the fuelling and emissions . Logical or not??

[200OOM]

Up date.,I changed all the fuses for the led ones. I did not check if any were blown. I now can see that the central locking fuse has blown, glimmer of blue light behind the battery. Could this be a clue?

[200OOM]

Hi, thanks for this . I think you are right about the 12v supply as ur was only getting through at 9v for what ever reason. It originally started with a clattering fuel pump relay . Other clues were I could not operate the alarm by turning the key. So with a blown central locking fuse , now replaced it MAY all work as it should. But flat battery now and some days away working it can't find out for a while . Hopefully put it all back as it was , happy that I know a little more about automotive electrics.

[200OOM]

All sorted. Not sure how but it all works as it should. Convinced connected to the central locking. Checked wireing , replaced all fuses, wd40 and general twiddling and pushing all connections tight. Battery on, alarm pipped and hazards flashed . Unlocked the car , ign on fuel pump primed and then start . Many thanks for all your help. I now have a much better understanding of how it all works . Now to get the speedo working!!!