1985 XJ-SC fuel delivery problem

[davidr]

Hi - there are possibly 3 sensors in your thermostat housing as per the drawing below

DBC3728 (labelled 9 in the diagram) is the temperature sender for the ECU and, if this or the wiring to it is defective, will give you the symptoms I described. This is available from Jaguar or SNGB at £38.76 each inc VAT

DAC2583 (labelled 11 on the diagram) is the sender for the instrument pack and feeds the temperature gauge. This is still available at £21.60 inc VAT

EAC2630 (labelled 12 on the diagram) is the thermal valve. This may be what your man is referring to? I'm not sure if your car has this. I think it is used for cars with emissions controls such as the air pump and EGR valve but I may be wrong. I don't think it would be fitted to a standard UK car? (I've never had a 3.6 so I'm less familiar) This part is no longer available.

If you could post a photo of your thermostat housing and the sensors installed that would help to clarify the issue.

3.6 thermostate head.jpg (13.86KiB)Viewed 1708 times

[Fivethirty]

David,

Thank you, again. This, I'm sure, will be very helpful. I've sent my man your text and diagram and asked him to send a photograph.
When received, I'll relay it to you.
Club spirit at its best!!

[ptjs1]

Peter,

I'm not sure why your "expert" is having problems sourcing the part.

IF its DBC3728, (it wi take him 30 secs looking at jaguars parts website to confirm) there are loads of places selling original, OEM or pattern items, or just buy it from your Jaguar dealer.

Good luck

Paul

[Fivethirty]

Hi Paul,

Thanks for that re-assurance that the part (assuming it's the correct one) is available.
As he has had the car for such a long time now it's why I'm getting more deeply involved.
I'll check my local Jaguar dealer, Hendy, to start with.

Peter.

[Fivethirty]

David,
I've now managed to get a pic of the alleged problem part as you asked for. Hope this will identify it. Thanks.

[davidr]

It would have been good to have a wider view of the thermostat housing so we could see how many sensors there are and what type. Are there just 2 do you know?

[Fivethirty]

David,
Just received this pic which shows a wider view as you requested. Hoping this may be of more help in your, (very much appreciated) diagnosis.
Cheers
Peter

[davidr]

Hi Peter - taking your last picture and zooming in I can see the 2 sensors on top and the one at the side.
I think (and others please correct me if I'm wrong) the one at the back with the single wire is the sensor for the temperature gauge, the nearest one on top is the sensor for the ECU and the one on side is what Jaguar call a 'Thermal Valve' that I'm not sure of its purpose.
The wiring connector for the ECU appears to have black tape around it? Has the connector or wiring been damaged? If there is a loss of connection here that would give the symptoms you describe.
If the DAC2630 thermal valve is the issue then your only route would be to find a used one. I'd suggest contacting one of the breakers that advertise in the magazine. Remember that an XJ40 could also be a source of the part.

[Fivethirty]

Hi David, Thanks for your further observations which I shall follow up and pass on to my Jag man. You make a good point about the apparently damaged wire. I will follow up on that, too. Thanks, for the tip about an XJ40 part being the same/similar. Great advice!
Hopefully, this problem will be sorted out soon. Watch this space and I'll let you know.
Thanks, again, to everyone for all the good advice.
Cheers...