sub tank relay switch problems

Hi Dave

There are other posts in archives re this (as I had same issue). To reset, disconnect battery for a while (I have to leave mine about an hour to get it to work - but many reports a few minutes).

May not be putting this right - but think most likely relates to earthing of accessories tripping sub tank computer.

For me the issue was caused by a car alarm.
Alan

Yep. Got a coupla ideas. I've had problems with sub-tank 2x before. Both quite simple and self created issues.

1. have you installed a turbo timer recently? If you have then this could be the problem. If the turbo timer was accidentally for a GQ 4.2, then this is likely to be ur problem. When the timer kicks in, it doesn't keep both ignition and acc circuits on until the motor shuts off. This is needed in the GU otherwise the sub tank goes into spaz mode when you next start the truck. Sorts itself out if you disconnect the battery each time. Solution - get GU timer or if you'r handy enough could probably change the wiring of the timer at the plug to keep both circuits running.

2. If the truck was started when the sub tank plug was disconnected, (or subtank removed) sub tank can also go into spaz mode. Need to disconnect the power from battery, and from the relay. Wait a while and reconnect. Should work fine from then..

3. Pump could have also seized. try giving it a tap with hammer whist somebody clicks the button in/out. If it's buggered, then just get a normal fuel pump from an auto shop with 3/8 fittings and replace. You'll need to change the plug wiring though.

4. Check power to the pump to see if it is getting 12v. If it is and pump not turning on, then its probably seized. (I had one do this too)

5. if you want another relay, I have a 4.2 diesel relay you can have for $30...I thought my prob was the relay the second time and it turned out to be problem 2.

Hope this helps

thanks for the advice Alan. I"ll try it tomorrow and see how I go. I have recently been adding heaps of accessories into the rig and could well be the cause.

Thanxs again

Dave

G'day, try putting a VERY good earth strap from Battery to Body and Chassis. Should help.
Cheers

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