Wiring at the fuel tank / extra grounding wire?

[DrWin]

I got the fuel tank out yesterday and noticed this:

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First off, the connector to the fuel pump needs repair/ replacement. I'm on it.

But why was the ground wire from the wiring harness to the fuel pump not used / connected? Ground was connected through an extra wire that ran to the passenger side of the front frame extension. (?)

[pk2678]

Is there really an extra ground wire for the fuel pump? I only know that there is an extra ground wire branching off the harness near the connector of the fuel sender unit. And that goes to the fuel filler neck.

[Bitsyncmaster]

Someone bypassed the inertia switch with that new ground wire. That will let your fuel pump keep running if the engine is running after an accident.

Now I have done the same but my inertia switch will unlock the doors, kill the engine and disconnect the battery when actuated.

You can test if the PO made any other changes by pulling the inertia switch open with the engine at idle.

[pk2678]

Someone bypassed the inertia switch with that new ground wire. ...

Thank you! That helped me to understand that situation too.

[Helirich]

Someone bypassed the inertia switch with that new ground wire.

They probably did this to get a better ground to the pump. I've just been finding this. Not sure what the answer is if you want to keep the safety aspect. I suppose there weren't many fires in the old days. (Before inertia switches) That was probably a lawyer forced option.

[Bitsyncmaster]

They probably did this to get a better ground to the pump. I've just been finding this. Not sure what the answer is if you want to keep the safety aspect. I suppose there weren't many fires in the old days. (Before inertia switches) That was probably a lawyer forced option.

I did post a possible solution in a thread some time ago. You can wire the inertia switch to provide the ground to the AUX relay that controls power to the ignition ECU. Then the inertia switch is only switching that 100 ma relay coil power. It then shuts off the engine and then the RPM relay shuts off the fuel pump. So then you can wire the fuel pump to frame ground.

[Helirich]

I did post a possible solution in a thread some time ago. You can wire the inertia switch to provide the ground to the AUX relay that controls power to the ignition ECU. Then the inertia switch is only switching that 100 ma relay coil power. It then shuts off the engine and then the RPM relay shuts off the fuel pump. So then you can wire the fuel pump to frame ground.

That's interesting. Thinking through a hypothetical scenario. You have an accident and a fuel line ruptures. Wouldn't the engine shut off for lack of fuel, there by causing the rpm relay to shut off the pump? I suppose if the line that broke was one fuel injector line, the engine could keep running. Kind of hard to imagine an accident where that happens. Of course, you also would have to be incapable of turning off the key. (Unconscious) Probably a pretty low risk.

[Bitsyncmaster]

That's interesting. Thinking through a hypothetical scenario. You have an accident and a fuel line ruptures. Wouldn't the engine shut off for lack of fuel, there by causing the rpm relay to shut off the pump? I suppose if the line that broke was one fuel injector line, the engine could keep running. Kind of hard to imagine an accident where that happens. Of course, you also would have to be incapable of turning off the key. (Unconscious) Probably a pretty low risk.

Most accidents the engine would probably shut off since your stopped in gear (for the 5 speed). So it would be rare that the engine keeps running.

[Ron]

That's interesting. Thinking through a hypothetical scenario. You have an accident and a fuel line ruptures. Wouldn't the engine shut off for lack of fuel, there by causing the rpm relay to shut off the pump?
Not if it was the return line.
And then there's ruptured tanks...
Or, you are knocked out, but the engine isn't...
-Just sayin'

[DrWin]

I'll remove the wire (for safety) and see how the engine runs w/o the extra ground wire. :D

[Helirich]

Not if it was the return line.
And then there's ruptured tanks...
Or, you are knocked out, but the engine isn't...
-Just sayin'

I don't think the inertia switch will help much stopping fuel coming out of a ruptured tank. Lol.

[Ron]

I don't think the inertia switch will help much stopping fuel coming out of a ruptured tank. Lol.Agreed, but it might stop the engine before 13.5 gallons of gasoline are ignited by an exhaust leak (like the one you are currently working on) and burn your arse up. :rolleyes1:

[DrWin]

Car runs well w/o the extra grounding wire. :D