Topic

I have checked for previous queries on this topic , hope I haven't missed a relevant one !
The car , 2004 , 1600 tf , the engine missed a couple of times close to home followed by
the engine management light . I bought a code reader which showed fuel shortage on no3
cylinder and general fuel shortage .
I have searched for the topic and relays seem to be the prime suspect.
So far I have;
Opened the tank inspection hatch , no power to the pump
Bought a replacement multi function relay for the boot mounted cluster
Checked / reset the inertia switch
Checked the under bonnet and dash fuses
Bought a new fuel filter (manual advises depressurising... no need, only a dribble of petrol)
Bought a secondhand YWB100970 engine management /fuel pump relay.........and there lies the
problem , where on earth does it live!
My manual shows a similar relay under the bonnet and also under the pressed steel guard
below the inspection hatch.....what I do have is a unit ,which I think is a security control unit
incorporating a large alloy heatsink mounted on the pressed steel guard and no obvious relay .
Am I correct in thinking the 2004 model has a different arrangement or ,more likely am I missing
the obvious (the polite version)

Any suggestions/ advice would be very welcome

On your 04 TF the fuel pump relay is next to the starter relay, both are housed in the left hand side of the boot between the liner and n/s quarter panel, of the 2 relays the fuel pump relay is the one to the front of the car.

The coil of the relay gets it's positive feed when the ignition is switched on from fuse 23 (fuse board in the drivers footwell) The negative for the relay coil comes from the engine ECU, this gives a 3 second ground signal when the ignition is first switched on and a permanent ground when cranking or engine running. The positive common feed is from comes from fuse 2 under the bonnet and is a permanent live feed (ignition on or off) this feed then goes to the inertia switch and provided it's not tripped then to the common of the fuel pump relay.

With the ignition switched on; at the relay you should have:
12 volts + on the brown and slate wire (common permanent feed)
12 volts + on the white wire (+ coil feed with ignition on)
Ground - on the black and purple wire (negative coil feed only when cranking or engine running)
12 volts + on the white and purple wire (N/O output to the fuel pump)

Remember the relay will only energise for 3 seconds when you first switch on the ignition just to prime the system and will only come back on when cranking or engine running, so when you have been looking for power to the pump the relay may not of had the ground signal from the ECU.

Brian.

Thanks Brian for the very detailed reply I will have look this evening. I replaced the relay as it was an easy thing to rule out
more investigation required.

Thanks again

Sandy

Brian
Well, I managed to test the relay connections as you detailed in your reply with mixed results

Brown/slate - 12 volts ok
White -12 volts ok
white /purple -no reading
black/purple- connected between earth and relay open circuit with ignition off , ignition on, cranking and engine running , it showed a higher resistance but not a short
I noticed an unusual "chirping" from the inlet manifold area when the ignition was switched off ,no idea what is going on there
Swopped the fuel pump relay , no change

My circuit diagram shows the black/purple wire connecting to an engine control module (D131)(my previously described box with the large heat sink?) Does this suggest a fault in the module in that is not providing a trigger to the solenoid
..........Oh for the continuously running SU pump on the B , nice and simple

The loom for the injectors runs through the inlet manifold.check that.also connectors to injectors and injectors themselves for consistent operation.

Sent from my GT-I8190N using Tapatalk

Hi Sandy,
Both power feeds are good and you have swapped the relay so it must be the ECU is not giving the ground signal to energise the relay. Next is to force the relay to energise by earthing the black and purple wire at the relay base, this should trigger the relay and you will get the onward positive feed to the pump on the white and purple wire. If the pump then runs you have an issue with the earth output from the ECU (D131 as you mentioned in your first post the box with heat sink)

You mentioned in your first post that you had bought another fuel pump relay, the part number you gave is for an MGF, the 2003 onward's TFs have a small relay the same as the ones in the drivers footwell fuseboard, infact the one next to the fuel pump relay is the starter relay which is the same; swap them over.

You also mentioned a noise near the inlet manifold when the ignition is switched off, this will be the ECU which gives a high pitch noise for about 8 minutes after turning off.

The simplicity of you MGB with the electric SU pump was quite dangerous, many early cars fitted with that system caught fire if involved in a hard RTA, if a fuel pipe ruptured on impact the pump would continue discharge fuel.

Later cars fitted with an electric fuel pump employ 2 safety sytems, on impact the inertia switch should disconnect the positive and as soon as the engine stops the ECU disconects the negative, hopefully no fuel pumping out.

Keep us posted on how you get on.

Brian

Thanks again Brian
I take your point about the B set up
I will try as you suggest rgarding earthing the black/purple lead
The small relay YWB000440 for the pump is one of three . I knew the starter relay was in the same block
not sure what the other is as my circuit diagram doesn't show these, probably should have checked the wire colours and tried to identify them .
Appreciate your help

Sandy

Brian
I earthed the black /purple lead as you suggested and the pump worked as normal....oh [insert mild expletive here] not too much of a surprise, the saga continues............time too trawl the web for a replacement ECU

Thanks again

Sandy

Just checked the new price for the required unit... OUCH.... think I may be looking for a "preloved" unit
I suppose it would be too much to ask for the ECU to be a straight forward swop ..."plug and drive".....

Northernlights wrote: wrote:

Brian
I earthed the black /purple lead as you suggested and the pump worked as normal....oh [insert mild expletive here] not too much of a surprise, the saga continues............time too trawl the web for a replacement ECU

Thanks again

Sandy

Sandy, fitting another ECU is not so simple as its digitally paired with the SCU/BCU (Security Control Unit or AKA Body Control Unit) which in turn is paired with the remote fobs and "I think" the reluctor ring around the outside of the ignition barrel.

You need to find out why you have lost the output from the ECU, have you checked the wire (black & purple) for continuity? it goes to the the upper connector plug on the ECU (black multi pin plug on pin 68) It would be unusual for the ECU just to have a fault with only that output! Is everything else working as it should?

Brian.

Brian
I had an idea that that might be the case...

I'm not aware of any problems other than the fuel issue . The last run I had in the car every thing was working until the fuel issue
While I am thinking about it the fobs haven't worked in my 18 months as owner. I have no record of the code, I lock by key and the
alarm activates (probably of no significance)
Does unplugging the unit cause any problems? (I haven't)
I will try the continuity check over the weekend .Thanks again

Sandy

No problem with unplugging from the unit, hopefully the continuity check finds a broken wire.

Brian.