‘Left’ selected; everything is normal? With ‘right’ selected; ‘right’ tank overflows?
If so; it’s almost certainly the changeover valve failing to switch to ‘right’ when selected - as David and Paul says.
Three possible causes; valve is not getting power (faulty connections), or not reacting to power. Either because it has failed electrically or is mechanical blocked from moving.
In the latter case; it can possibly be cleaned to restore function. You can test power in situ, but if OK the valve should be removed for testing - or replacement.
However; the function of the return valves should be checked as a matter of routine - return fuel only(!) to the selected tank. Malfunctioning return valves will confuse the issue; fuel return and fuel delivery are two different fuel circuits - even if controlled electrically by the same switch. Incomplete switching by the changeover valve may partially draw fuel from both tanks - return should therefor be checked…
Again; the 3 fuel hoses at the changeover valve must(!) be clamped before disconnection!
As an aside; as very little fuel is consumed by the engine during idle - most of the pumped fuel is delivered back to the tanks. A failed changeover valve will very quickly pump fuel from one tank to the other…
Quin,
What does the fuel gauge read when the left tank is selected? From one of your previous posts you said that the engine ran until the left tank went empty and then the engine died. Does the the fuel gauge when the left tank is selected just show that the left tank is empty?
BTW, as long as the fuel selector switch on the dash is working properly you should be able to get the engine running again and the fuel system working properly by testing the fuel changeover valve and both fuel return valves and replacing any that are bad. Although the fuel quantity senders are related, any problems there will not affect the engine running and can be dealt with later. I have had problems with the fuel quantity senders (located inside the fuel tanks) over the years and they are pretty easy to sort out. First thing is to fix your fuel delivery issues to prevent fuel overfilling your right fuel tank.
Short the sender cable to ground and see if the gauge reacts, it should go to full. If it does it would mean that you sender is not working.
I suggest you have a look also at the switch itself, maybe it’s part of your problem.
Neither. If it goes to full, gauge, switch and wires work. The sender is bridged in this test. The sender will read empty anyways as the tank is empty. This all misses the point for now as the tank is empty and Quin should focus on getting the valve fixed.
I changed that crossover valve it seems to be running now have not been able to do further testing at this time .It seems like I have a bad nuetual safety switch I have to wiggle the shifter to get the starter engaged .Do you know where it’s location is?
Quin,
Sure. Attached is a picture that I took last year about this time when I was getting the replacement engine from my 1987 XJ6 parts car ready to install into my 1984 XJ6 Vanden Plas. That Neutral Safety Switch is located on the left side of the transmission and is circled in red in the attached picture.
I had the same or similar problem with fuel pouring out of the right tank. Thanks to this forum I was able to fix that. My problem was the changeover valve. I took it off the car and was able to clean it with carburetor cleaner. I used a phillips screw driver and pushed it in the center hose opening and kept doing that until I felt some movement. I was able to free up the internal part (plunger) not sure what it’s called. I hooked it up to a car battery and could hear it clicking, which was a good sign. I think it was stuck from the car sitting unused for 10 years or so. I thought I’d try that first before buying a new one that cost around $100. This might not be the correct procedure but it worked for me. Make sure to clamp off the fuel lines well or you’ll have fuel all over the place.
I believe my fuel delivery problem is solved but Now since I drained the fuel and added new fuel when the tank switch is depressed the gage does not move off empty and when released only moves a tiny bit the tanks are almost full and the car starts and runs fine until I shut it off it then won’t turn over again until the car sits for a couple hours he battery is new and the car is charging
No gauge readings means your tank units does not operate the fuel gauge. The gauge is powered by the ignition key; the changeover switch just connects the gauge’s ground either to the ‘left’ tank unit (switch ‘in’) or the ‘right’ tank (switch ‘out’). To investigate you have to access the tank units connections…
The (unrelated) intermittent ‘no cranking’ is somewhat strange. The first step is to locate the starter relay - and connect the black/green connector directly to ground; this will bypass the start inhibit switch. If this resolves the problem; the start inhibit switch must be accessed for checks and adjustment…
If the problem persists; with the fault present, jumpwire from batt pos to relay white/yellow - this should crank the engine each and every time. If so; the relay, starter solenoid and starter is OK - and the fault is likely in the ignition switch. If there is ‘no crank’ with this test; either the relay faulty (does not ‘click’), the solenoid fauty (does not react) or the starter itself not turning…
A sometimes fault is burnt contacts inside the starter solenoid - or dirt inside the solenoid bore preventing decisive engagement. Which may be aggravated by heat
There is no particular reason for the ign key to be heat sensitive - and one would expect a fault here to occur occasionally at any cranking situation. However; connecting a test lamp/voltmeter between white/yellow and ground - with the ign key to ‘crank’ the test lamp should light up (or the voltage meter read 12V), each and every time…
It means that the safety switch is misadjusted or broken. Or did you check that thoroughly, then I don’t know. If not, scroll up! First to my post and as it is heat related, maybe more likely to Frank…
It is likely that your Neutral Safety Switch is out of adjustment. I provided you with a picture of that Neutral Safety Switch on the left side of the transmission. Scroll up about 2 weeks and you will find it. It is possible that an adjustment of the Neutral Safety Switch is all that is required. The same switch turns on your white back up lights. Do the back up lights come on when you put the shifter in Reverse?
