Fuel tank change over problem

[baders Junior Member Find all posts View Profile Close baders]

Hey all. Long time since I've posted here. Still have my supercharged petrol V6 '96 GXL and she is going strong. Except for the fuel system recently. Had a problem a while back once when changing from main to sub tank. She conked out on the freeway. Quickly flicking back to main and running again. Couple of days ago was on sub tank (half full), flicked to main (half full), and she would not fire up on the main tank. Switch seems to be working as obviously something is happening. I'll be checking the solenoid when I get home from work but my questions are;

1) I've looked up ToyoDIY, and there only appears to be a "return fuel solenoid" listed as part number 77720-60010 (Glen_EP has one on Ebay). I don't see a "main tank solenoid" (7771060040) ?
2) Can someone please advise which one I might need to replace ?

Model is a 1996 petrol GXL 5VZ_FE. Thanks in advance.

[glen_ep Addicted PP Member Find all posts View Profile Close glen_ep]

Hey baders the petrols only have an electronically controlled solenoid for fuel return, the 'feed junction' as I like to call it is mechanical in some manner. I'm guessing it's just a one-way junction. The diesels are different, they have 2 solenoids, each controlling feed and return.

Another difference is the petrols have 2 pumps, one in each tank. The diesel, I believe, has a single pump up front, sucking the diesel.

This is all important because diagnosis of each will be different.

In your case I would suspect the main tank pump is not working, or a fault in the circuit preventing it from working. I'd guess another possibility of the feed junction being jammed preventing fuel to pass through. I doubt the return solenoid having an issue would prevent the vehicle from running - but it might result in a bursting line.

To diagnose I'd be disconnecting the feed lines from the feed junction, tank sides, have someone turn it over, and watch if each hose sprays according to switch location. I haven't done that before and it's obviously a dangerous thing to do with fuel, and the pressure will be high. Obviously have a cold vehicle and nothing around which could ignite it. A smarter first step might be to check pump wiring for active power.

I have unplugged hoses from the return solenoid for testing, the pressure wasn't high but it was a decent flow of fuel.

I have both of those junctions new if you need them. Not listed on Ebay though, and cheaper outside of there too.

[baders Junior Member Find all posts View Profile Close baders]

Thanks Glen. Just flown home from work and will start looking at this tomorrow.

Looking at the wiring diagrams, either the fuel tank select switch OR the ECU can change over between main and sub fuel pumps (and changeover solenoid too). This is done via the fuel pump select relay, so this relay could be a problem too. When the switch is put into the sub position, it energises the relay and this switches over to sub fuel pump (and solenoid). So lots of things to check before swapping out the solenoid, as you say. I'll post back tomorrow hopefully with a solution.

[baders Junior Member Find all posts View Profile Close baders]

Pretty sure the problem was a sticking fuel pump select relay. Bridged out all relays at the diagnostic plug and main pump ran the car OK. Tested output to pump at relay (red/black)and 0 volts when relay de-energised. (Should be 12v). Unplugged relay and tested on test bench and it was intermittent. Cleaned up with contact cleaner and reinstalled and seems to be running OK. Off to look for a replacement anyways. Fingers crossed that was the problem.

[CoreyTroy Member Find all posts View Profile Close CoreyTroy]

Well problem solved...

[baders Junior Member Find all posts View Profile Close baders]

OK so far no further problems. I haven't been able to locate an exact replacement relay but I could certainly find one that would substitute. Would just need to cut off the OEM plug and solder in a replacement. Hopefully won't need to do this as this one has been running OK since cleaning it up with contact cleaner.