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V12 fuel changeover valve

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V12 fuel changeover valve
#1
  This topic is about my 1988 Daimler Double-Six
double 6 Avatar
double 6 Silver Member Graham Hepburn
Cairns, Queensland, Australia   AUS
I have had 3 failures of aftermarket fuel changeover valves in (3 years and 7oookm).This valve changes pickup from L or R tank. Valve would draw fuel from L and R tank at same time when R tank switched. Thus all return fuel goes to R tank which soon overflows, whilst emptying L tank. I also had one not open R tank so engine stopped. Have just fitted a c/o valve from a Toyota Landcruiser part no 77710/60160 which should prove more reliable. I made a bracket from 1" by1/4" Aluminium bar and fitted it to existing holes. A tight fit, and had to put a right angle brass fitting between LH tank and valve so hose did not kink. Ports are different to Jaguar, so check flow by blowing through whilst connecting to a battery.

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PeterT Peter T
Oxford, Oxford, UK   GBR
Graham, these valves can be a nightmare. I've tried to think of a re-design of the fule lines and tanks, but not come up with anything better than the original arrangement. When the problem keeps coming back, it's often due to to dirt in the system. It may be worthwhile trying to flush it out. There may be rust in the fuel tanks. How old are they? Do you keep them full? It seems, I think, to get worse with less frequent use. If it is dirt, it can also block the fuel pump to add to the misery.

As a short term measure, it's possible to put extra filters in the system. And as a very short term, whack the valves with a small hammer to wake them up!

In the end, we changed all the fuel lines and the tanks of my DD6. But we still had dirt coming from somewhere. I am now keeping my fingers (and arms and legs) crossed that the problem is resolved for a few years.

Do let us know how the Land Cruiser valve goes

double 6 Avatar
double 6 Silver Member Graham Hepburn
Cairns, Queensland, Australia   AUS
We had put filters in front of both return line valves, and on both tank outlets before changeover valve, and the problem came back to the changeover valve. Running RH tank it would draw from both and overfill R tank with return fuel. Last failure, would not draw from RH tank when switched to RH, until you tapped the valve. Will test the new system with a 500km run this weekend. Our problem I am sure is with faulty valves, and our supplier eventually admitted to same.

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Orlando, FL, USA   USA
would this fix work with the XJ-6 as well ??

I have had the right tank overflow issue too.



1965 Jaguar S type
1984 Jaguar XJ-6

double 6 Avatar
double 6 Silver Member Graham Hepburn
Cairns, Queensland, Australia   AUS
Do you have carbys or injection? My problem is in a fuel injected car. If the changeover valve fails it draws fuel from both tanks. If you have selected RH tank, all return fuel will go to RH tank, as you have opened that return valve when you select RH tank. If car is carbureted there is no return fuel. Did more than 500km at weekend, no problem. Graham

Orlando, FL, USA   USA
In reply to # 14581 by double 6 Do you have carbys or injection? My problem is in a fuel injected car. If the changeover valve fails it draws fuel from both tanks. If you have selected RH tank, all return fuel will go to RH tank, as you have opened that return valve when you select RH tank. If car is carbureted there is no return fuel. Did more than 500km at weekend, no problem. Graham

Graham,
fuel injection, 4.2 liter original engine and f.i. system.



1965 Jaguar S type
1984 Jaguar XJ-6

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