No Feed To Fuel Pump

[balnacoul]

Having found some enthusiasm to get this long build moving again, got most of the electrics working.

Using original sierra loom. From the relay which feeds the pump via a fuse, I have 12 volts at 30 (Red) , 12 at 86 (Black) but also getting 12 volts at 85 (Blue/Red which connects to EEC IV module) and nil volts on 87 (Black/red feed to pump). As the donor was not a runner therefore module unknown good/bad, took a punt on a flea bay replacement for £10 but still the same problem. The relay checks out okay and I have tried a replacement. Any suggestion on where to look now.

[Guest sandy77uk]

if you feed a 12v supply directly does the pump turn over?

[balnacoul]

Pump is ok, just not getting any power out of 87 on relay to feed it

[Dave R]

impact cut out fitted ??

[Jez Morton]

Easy to miss but check the ECU connector is done up, I'm assuming its the Sierra one and has a bolt through it. Yyou can have a few turns on the bolt and it seems secure but the pins are not quite in.

 

Jez

[balnacoul]

Not getting power to point prior to cut out switch

 

Yes sierra ecu connector bolt tight and socket fully engaged

[Longboarder]

Switching by the ECU is to earth. So you won't have 12v at a wire that comes from the ECU. It will be open circuit when off and direct to earth when active. Apart from that you will also find most ECU's work on a reference 5V not 12. But you have 12v at 85 and 86. You need to trace both wires to their sources, and make sure neither has any additional connections. The likely conclusion is they are both ignition switched live and goodness knows where the switching earth from the ECU to the fuel pump relay is actually going. But you need to find it and replace one of the 12v wires on 85/86 with it.

 

Nigel

 

Simple dirty check, cut the blue/red that comes from the ECU about 6 inches from the module (you can always rejoin it later) and splice a fresh wire from it to 85 on the pump relay. Does it work now?

[fry61]

Maybe a stupid suggestion---- are you making your tests with the wires disconnected from the relay? If not you may be reading 12volt on each side because of the relay coil & the very small load imposed by an electronic test meter.

[balnacoul]

Thanks Gents, have done some more checking before fingers became close to frostbite !

 

Red 30 comes direct from battery.

Blue/Red 85 goes direct to ecu with no other connections.

 

Testing with wires disconnected from relay give 12v at 30, 12v at 86, 0.04 at 85

[knights_templar]

Hi

 

put a bridge wire in the loom terminals where relay pins 30 and 87 go (make sure it is those connections, terminal 30 is 90 deg to other 3 terminals 87 is directly opposite that). does the pump run?

 

....yes as you have 12volt to pin 86, I assume the ECU is switching earth, check by putting ohm meter to terminal where pin 85 would go and a suitable earth contact. switch on ignition, should get the meter showing a circuit for approx 6 seconds.

 

..........................................yes relay fault

..........................................no check wiring from 85 to ECU, if OK probably ECU

 

....no you have a connection problem between pin 87 and the pump

 

the above assumes you have double checked the readings you have given above

 

regards

Edited February 11, 2012 by knights_templar

[Jez Morton]

Let's not forget that Ford for some bizarre reason decided to be different to the rest of the world and use relays where pins 30 and 86 are swapped compared to standard auto relays. Can you clarify, you have no operation at all from the pump, normal operation would be for the pump to run for a second or two when ignition is turned on then stop, it will then run when the engine turns over. Check pin 85 for 0volts ish when you put ignition on which then goes back to 12 volts, then try cranking to see if its 0 volts again.

By the way don't try to measure ohms on a live circuit it doesn't work and can damage your meter.

 

Jez

[Guest peter2b2002]

when I stripped the sierra loom I cut out all the wires that I didn't need,electic windows sun roof etc + loads of other wires that didn't seem to needed, end result when refitted into my 2b all worked exept the fuel pump - - - no earth to the fuel pump relay I had 12v on the pins on the relay though fitted an earth bingo all OK, now I have dumped that way of turning on the fuel pump and now use a kill switch to turn the pump on

peter2b

[knights_templar]

Hi

 

seem to have reversed orientation of pins in last comment, 87 is the odd one not 30. but test principle is the same.

 

Agree with Jez, Ford did change pin numbers from standard (not international DIN) but you mentioned you had 12volts at 30 and 86 so it makes no difference in this application.

 

looks as though you found the problem, lack of earth. although you have a simple fix, the main reason the ECU is used to control the fuel pump is one of safety. I would still find out why it isn't able to, or if not fixable, fit some sort of inertia cut out to the system.

 

regards

[balnacoul]

Now fingers have thawed out enough to type. Have unwrapped all wiring checking connections etc. When I switch on ignition I am getting12 volts on 87 (Pump feed) for one second, then reverts to 0. Didn,t hear pump attempting to run, tried direct feed and ******* nothing (it did work earlier in this saga with a direct feed). Have now thrown hissy fit and will continue once I get replacement pump. Thanks to all for your advice in the meantime.

 

Regards Bill

[steve in stockport]

ok so you have power for 1 second which is correct, then the pump cuts out til the engine is running and demanding fuel.

you say the pump ran ok the other day, since you've messed with it have you ensured you've got a good earth for the pump?