Greetings Everyone! I'm working on a 1977 XJ6C that's been a years-long restoration project, passing through many hands....
The fuel system has been an issue, with the right hand fuel pump filling the left side fuel tank! Someone left out/discarded the in-line check valves...
Anyway, I've rigged check valves and replaced the fuel tank selector switch, the left fuel pump and the left tank sending unit. When the engine is running, the Right Side Fuel Pump delivers 3.5 psi fuel pressure at 12.2 volts and 2.4 amps. The Left Side Fuel Pump delivers 2.3 psi fuel pressure at 11.8 volts and 2.3 amps.
I've been wracking my brain to figure out what's going on here! I can't find any specs on minimum fuel pressure. I've by-passed the inertia switch.
As previously stated, the vehicle has been off the road for years and passed through I don't know how many "mechanics" hands up to this point.
Can anyone shed any light on this for me? I would greatly appreciate your help!
Regards, George

 

Hey geocap - you posted a question about a 1977 xj6 in the forum for the X351.
The X351 is the XJ model from 2010 to 2019.
Have you considered browsing through the forums and maybe reading a little to get familiar with it first?
Maybe if you find the forum that includes 1977 XJ6s you might find discussions that have already answered your question.

 

Thank you for putting me in my place!

 

Hi George,
The Jaguar twin tank system works well for a long time when everything is new or at least starts out new. The problem starts when after a period of years and maybe some neglect the tanks start getting rusty, from there you get contaminated valves, fuel pumps, filters, check valve, lines, carbs and on later xjc's with fuel returns, return valves. I'm sure you have a copy of the factory service manual as it's pretty much mandatory if you're actually servicing one of these cars, my preference is the green one. As your car has carbs, does it have a return line to return fuel to the tanks, and two return valves in the rear inner wheel wells? How did you "rig" the check valves?
As far as the pumps go, looks like you're dropping around a half a volt to the left pump which may not be such a big deal but it's probably a connection problem somewhere so check your wire end connectors and grounds. If you're returning fuel to the wrong tank it's likely the changeover valve or a return valve which most likely points to rusty tanks, and it could be the tank switch (but you've replaced) or connections there. The FSM is going to be needed for a good wiring diagram. Be aware this condition can also cause raw fuel to be forced into the evap lines all the way to the front passenger side fender where the charcoal canister is and can pour fuel out the open port. This means raw fuel pouring out underneath the front passenger side fender, it's a serious fire hazard so please be aware. XJC's are relatively rare and desirable cars, I hope you can get yours sorted out and enjoy it.