dirtyundies

I have a 93 civic hatch, it wouldn't prime so we replaced the relay and it worked for a week and stopped, replaced the fuel pump and still nothing... Checked the relay again and it was fried so we replaced it again and it still won't prime.. Now we aren't getting power to the pump, all the fuses are fine... If there's a short somewhere how would I find it?

dirtyundies

And what did it short if the relay and fuses are OK!?

2point1

Check the thermostat housing ground.

Check the main relay plug for

Check to see if you have 12 volts to the yellow and black/yellow wires. The black/yellow wire is a switched 12 volts.

Check the black wire for ground.

Check the green/yellow wire for ground. This is a ground trigger that the Ecu controls.

fcm

Start by checking the ground for the PGM-FI Main Relay, [fuel pump relay] it is grounded at the thermostat housing, test for all three powers at the relay, unplug the relay and with a 12V test light, [not LED type] for power, there should be one power, torn on ign. and you should have two powers turn ign to start and there should be three powers

1. hot at all times, ign. off.
2. hot in run, ign. on.
3. hot in start, ign, in start/crank position.

You said the relay was "burnt out", do you know what part of relay was "burnt out" the fuel pump relay or the fuel injector relay? 94

dirtyundies

It was the fuel pump relay that was burnt I'm not sure where... is there a diagram I can look up to see which three wires are power?

dirtyundies

Yellow has constant power, yellow/green and yellow/black have no power even when cranking... What's that mean

2point1

Yellow/green will only have power when the Ecu triggers the relay.

The yellow/black is power out to Ecu.

Does the black/yellow wire have power with the ign on?

dirtyundies

No it doesn't

dirtyundies

Wait yea sorry black/yellow has power.. I was checking yellow/black oops

dirtyundies

The relay is still fine

fcm

The green/yellow, according to 2point1 is the ECU/ECM control lead it is a ground but only controls the fuel pump relay, the fuel injector relay is controlled by the ign. switch, the hot in run lead. 94

dirtyundies

So if yellow and black/yellow have power what do I check next? Also I don't hear the relay click

fcm

There should be at least one click when you turn on the ign. [fuel injector relay] hold relay when turning on the ign. to see if you can feel the click, if not the relay ground [black] is bad or no power on the switched power to the relay. 94

dirtyundies

I don't feel or hear it click...

2point1

Check the black wire for ground. You can stick a piece of wire in the plug where the black wire is and touch the other end of the wire to the chassis.

With the piece of wire grounded to chassis and touching the black wire in the main relay plug see if you have 12 volts at the yellow/black wire. The yellow/black wire is what give the Ecu 12 volts with out 12 volts to Ecu the fuel pump won't prime

dirtyundies

Black/yellow or yellow/black? Black/yellow has power, yellow/black doesn't

fcm

Did you unplug the relay and test for the three powers? 94

dirtyundies

Yes yellow and black/yellow have power that's it

2point1

Yellow/black. It give the Ecu 12 volts. With out it the Ecu won't turn the fuel pump on. Trying to narrow it down to where the probelm is.

So you have 12 volts to the yellow and black/yellow wires. Now do you have ground to the main relay plug? It's the black wire.

dirtyundies

Yes I put a wire in the black and grounded it to the chassis like u said then checked yellow/black, still no power

2point1

Was the ignition on when you did it?

dirtyundies

Yea