Pump works, but getting no power.

[Delorean3610]

So the car ran great two weeks ago, but now won't start. After some checking, 12v straight to the fuel pump runs it but no power is getting to it.

I've checked that the relay is receiving 12v. 12v to ground on the relay socket is good, and bypassing it yields no results.


Fuses 1 and 7 are receiving 12v.

What else should I be doing.

[Bitsyncmaster]

Sounds like your inertia switch may have opened.

[Delorean3610]

Sounds like your inertia switch may have opened.

It wasn't popped up when I checked, is there something I'm missing.

[Bitsyncmaster]

You need to put a meter on the connections on the fuel pump. Then you can determine if it's the ground side or power side at fault.

[Delorean3610]

You need to put a meter on the connections on the fuel pump. Then you can determine if it's the ground side or power side at fault.

I have continuity between relay socket and the positive lead of the fuel pump, and continuity between the inertia switch socket and negative socket of the fuel pump.

[Delorean3610]

When I jump the relay I only get about five volts at the fuel pump to ground.

[DMC5180]

That's not a sign of bad input Voltage. That's a sign of resistance from poor contact of the switch contacts. Once it starts it gets worse until you have a melt down.


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[David T]

If you have an "early" inertia switch, there was a recall because they go bad. The newer one has a splotch of white paint on it and it was moved to the side kick panel, not on the Lambda counter.

[PJ Grady Inc.]

If you have an "early" inertia switch, there was a recall because they go bad. The newer one has a splotch of white paint on it and it was moved to the side kick panel, not on the Lambda counter.

Correct David the 81 issue inertia switch was recalled for exactly this reason so once this switch is replaced with the revised '82 on switch the problem will not recur. The recall specifies relocating the switch from the lambda counter bracket to the bulkhead panel behind the hood release bracket to avoid incidental activation and more easily identify the switch is updated. All 81's are part of this recall and there are two versions of improved factory replacement parts to add to the confusion. The recall switch #109277 had the white splash of paint. The later switch #111209 used in 82 & 83 cars had a small S stamped above the production number on the switch housing. Both improved switchs were issued as replacement parts but both used a dark steel center terminal in place of the early defective units all brass electrical terminals. All 81 owners who have the switch mounted on the lambda bracket should inspect to see if its updated and then relocate if it passes muster. This is rather important for all '81 owners as the failure rate for these switches is approaching 100%.
Rob