XJ6 S3 fuel tank breather?

XJ
1

Hello all, Can anyone clear up a question for me please? Do the fuel tanks on a 1985 XJ6 S3 4.2l Sovereign have breather pipes? I have noticed that the fuel flows quite slowly from the tank to the fuel pump but when the filler lid is left open its much quicker. Is this normal?
Con

2

**
Tank venting is absolutely(!!) essential, Con

The ‘European’ set-up is a simple hose from the filler neck on each tank to ground level. US models have the closed tank ventilation, which is more complicated…

However, the vent hoses are fairly narrow - catering for the slow depletion of fuel in the tank with the engine running. So you symptoms doesn’t imply a vent problem - manipulation of the filler lid is commonly used to control fuel flow when draining the tanks…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)
**

3

How did you determine that Con?
The tank to pump flow is gravity fed and the vent tube is quite thin and all the way from the charcoal canister, it could be clogged of course, but it is restrictive and the filters do add some more.
If your venting system is clogged the hydrologic suction of the pump is strong enough to implode the tanks,…
A first indication of an over restricted pump. input would be cavitation and it would be clearly audible.

A better test would be to disconect the hose before the pressure regulator and check the flow with the pump running.

Aristides

4

Hi Aristedes, I did disconnect the hose at the filters that I installed (similar to the ones that ypur installed) between thw tanks and the tank selector solenoid. Thup but not completelye fuel flow was not as strong as I remember when I disconnected it one other time. I also tried removing the actual bronze filter and it improved a little. I haven’t tried actually opening the filler lids. This may prove the problem and solution. The bronze filter was a little blocked up but not enough to cause a no flow problem. Still investigating.
Con

5

This thread is related to another thread Ive had going for some time so perhaps all further correspondence to XJ6 Series 3 Stuttering on acceleration when cold.
Thanks
Con