RX7 allnight

i only get 12v when cranking. no power when in "on" mode on the ign

RX7 allnight

btw: i was driving it and the fuel pump just cutt out.(i thought i ran out of gas...) went to check for 12v and i only get it when i crank it over...

gsl-se addict

iTrader: (3)

That is normal for an 84-85 car. The fuel pump is powered through the fuel pump relay. The Emissions Control Unit kicks on the fuel pump relay when:

1. cranking
or
2. engine running

The ECU knows the engine is running based on the tach signal (trailing coil (-) terminal). If your trailing ignitor went out, your fuel pump would cut out. It would have power when cranking, the car may start for a few seconds and then die. This is because the fuel pump would turn off when you released the key from the 'Start' position.

To fix:
- check spark on trailing
- if no spark, it is probably a bad trailing ignitor (box on distributor closest to alt)
- if you have spark and still has the problem, replace or bypass the relay

I am assuming you have an 84/85 12A car. GSL-SEs are similar, but a bit different in how the fuel pump relay functions.

RX7 allnight

before it went out i would always hear the pump.. if it was running or not same on my other 83" i think this one is an 83 as well...
before with key to "on" position i would hear the pump now i only get 12v when cranking.. iall check the trailing coil and see if i get spark

Jeff20B

iTrader: (13)

I too am dealing with the dreaded '84-'85 fuel pump trick. My solution was to remove one of the storage bins and hook up the fuel pump directly to a battery since I need to pump out some old gas that's been sitting since 1994.

These cars have a safety feature which prevents fuel pumping if there is no tach signal. I forgot how to defeat it ie which wires to jump on some relay somewhere. Anyone know?

RX7 allnight

my tach works

gsl-se addict

iTrader: (3)

If the car is an '83, there is no fuel pump relay. Power goes from key to fuse to pump. Could be a problem in the ignition switch. Have you noticed anything else that has stopped working recently?

All '79-'83 1st gens are like this. The fuel pump should run whenever the key is 'ON'. Starting in '84, they added the fuel pump relay and the requirement that the pump would only run if cranking or engine running (tach signal).

Percentage

iTrader: (7)

on my '85 GS my fuel pump turns on when I turn on ACC but i removed the ecu. perhaps you should try that.