Non Starting.

Hi Volker,Greetings from Nigel Gibb E3 1975 3.0si .I'm having starting problems,it seems I have no feed to the fuel pump.Ive checked the ECU pins 16 and 24 are liv e with the ignition on. Also the pump relay ( which is new ) is showing pins 30/51 are live but 87 is dead .I've noticed that there are two identical green and white wires one from 30/51 and one from 87 which I'm guessing is going to the pump.Look forward to hearing from you.The main relay I'm sure is not an issue I've tried three and even run the car on the original 50 year old version that was on the car from new.

Hi Nigel,

if 16 and 24 are +12V, check whether ECU sets pin 19 to low to activate fuel pump relay. At least 1 second after switching ON ignition.

Hi D djet,Thank you,Can I ask my electrical skill is not great.I just tested 16 and 24 with a test light. With a voltmeter do I put one end on the pin and the other to earth ,car metal with the ignition on to read the voltage ? When I was trying today I did hear the pump very briefly make it normal pre starting hum ! Just once in several attempts.Nigel.

Hi Nigel,

just measure against +12V (e.g. pin 16) without causing a shortcut.

Thank you Dr Djet Volker

Hi Dr Volker, I tested pin 16 ,which is 12.75 V same 19 but 24 is 8.75.I connected my spare ECU and had the same readings. What do you think is wrong ? Thank you Nigel.

Hi Nigel,
this should be a cable issue, maybe at the relay-connector.

Regards
Norbert

Hi Nigel,

if 24 does not receive +12V, injectors will never work. So fuel pump works for 1s when you switch on ignition ? 19 should read 0V for 1 second. 0V activates fuel pump relay.

Hi Norbert, I will have another look at the pump relay connections tomorrow. What does OV mean  ? Thank you for your help ,let's hope we can sort this ,Regards Nigel.

OV means 0 Volt

Regards
Norbert

Hi Norbert,I've checked theconnections to the pump relay and they all look good .Turned on the ignition and both pins on 87 are dead..I've also checked the main relay connections all good and the double clear plastic block connections mounted on the mounting bracket of the top brake servo .RHD cars have two.Im really lost.I drove the car Monday,although it was slow to start and warm up.Regards Nigel.

Hi Nigel,
after 'ignition on' pin 87 of the fuel pump relay will be +12 Volt only for one second.
You have to find out the reason for the voltage on lead 24 is so low.

As Volker described, this is the power source for the injectors and they will not work with such a low voltage.

Regards
Norbert

Hi Norbert ,Quick update I've just discovered that with the ignition on with a   test light pin 87 is on ,sorry my poor earhing when I tested before .but no supply to the pump! If it's not a silly question would it be possible to remove the double connector at pin 87 and run two cables outside the car from pin 87 to see if the pump then works ?? The light stayed on while the engine was cranking over. Regards Nigel.

Hi Nigel,
I don't know what you mean with TWO cables from pin 87.

Sure, one cable to the pump from the pin 87 - but the second one has to be ground.
No problem to run the pump using a different connection.

Regards
Norbert

Hi Norbert,I've checked again today.Ignition on ECU pin 19 and 16 ,12.50 volts pin 24,  8.67 volts What could be causing the lower voltage? The pump relay, pin 87 is dead pin 86 live and pin 85 clicks when I put the test light in to the terminal. I'm beging to think I will never get the car going .I can see two cables go from the pump relay to up and over ( my drivers side ) wheel arch to the I guess the rear window shelf ,if I'm reading the drawing right one to the fuse and one to the pump.both green and white ,but the actual pump connection under the car looks like one green and white and one brown .Does that mean there is a seperate earth connection somewhere at the back ? When are you coming to London next ? Wishful thinking .Regards Nigel.

Hi Norbert, when you say test pin 16 against 19 pins on the ECU  do you mean connecting each end of a volt meter to each pin  16 and 19 at the same time as I turn on the ignition to test the pump with voltage ie the two second OV mode.? Thank you Nigel.

Yes, Nigel - you will measure +12 V between 16 and 19 for a second or so after switching ignition on.

But you have to find out the reason for the power connection to line 24 being so bad. Maybe you have other problems, too - but it makes no sense to check out everything without repairing the fault you have already found.

Be careful...
don't forget a shortcut could damage the ECU, the harness or other components.

Regards
Norbert
 

Hi Norbert ,Thank you for your reply .I've checked the fuel pump connection plug terminals ( I took them out ) they look brand new. One cable is Green and White one is Brown.im sure this is a earth cable ,but where it earhs I cannot see. Could the low voltage at 24 and the non pump working be the ECU at fault ? Is there anyway of proving the ECU is faulty without shorting 19 and 16 with voltage? I do t want to damage the system.which is highly likely with my lack of knowledge..Regards Nigel.

Hi Nigel,
for testing the power source at pin 24 you should disconnect the ECU-plug and then install a bulb (I think a headlight-bulb will be good) between pin 24 and 11 (ground). If you don't measure about 12 Volts with ignition on, there is definitely a problem with the cable connection. The relais powers both '16' and '24', therefor it must be the cable 24.

Regards
Norbert

Hi Norbert ,Thank you for that ,Just to be clear,a would a normal test light which I have one end connected to pin 24 and the other to pin 11,this and together with exactly the same ( together with the pins of a volt meter and test light together ) for the test ? Plug removed fron the ECU. .Today I retried my spare ECU and I was surprised to hear the pump hum as it should also the pump relay was clicking,I tried to start the engine cranked for maybe 10 seconds before I realised I'd forgotten to replace the coil HT when I tried again the hum from the pump and the relay stopped clicking..Regards Nigel.Regards Nigel.