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Discussion Starter #1
Buddy has a 92 civic mt sedan won't start. Cannot hear fuel pump at all. Took his main relay plugged it into my 98 civic and mine ran fine using it. Put in a new fuel pump still no fuel pump activity and no power to plug using voltmeter. His main relay clicks once when trying to start. Starter is turning fine. Is it possible that my 98 civic does not require something in the main relay that the 92 needs? Also can anyone tell me for sure which pins on the pump harness are + and -? There is power at the Mr harness with ignition on and off.
 

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The yellow and black/yellow are 12 volt. The black is ground. Check the yellow and black/yellow wires for power.the ignition needs to be in the on position when checking for power at the main relay. Check the fuses and check the thermostat housing ground. All so check the black wire at the pump plug for ground.
 

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Buddy has a 92 civic mt sedan won't start. Cannot hear fuel pump at all. Took his main relay plugged it into my 98 civic and mine ran fine using it. Put in a new fuel pump still no fuel pump activity and no power to plug using voltmeter. His main relay clicks once when trying to start. Starter is turning fine. Is it possible that my 98 civic does not require something in the main relay that the 92 needs? Also can anyone tell me for sure which pins on the pump harness are + and -? There is power at the Mr harness with ignition on and off.
1) I could help you in person, if you are close to San Jose and REALLY need some one to help diag the problem.

2) Check the fuse first, then power at the pump. This will tell you which side of the circuit has an issue.
 

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Discussion Starter #4 (Edited)
The yellow wire with green and the solid black wire show no voltage, the solid yellow wire and the black wire with white stripe 2.81 volts. I cleaned the thermostat ground and swapped the fuses listed in another thread as mandatory. no fuses where blown on a visual check of dash and underhood. I am at the point of taking out the carpets and checking wires and having to order a Ecu from eBay. The relay when in my hand only clicks once or it seems that way.the cel stays on doesn't flash. I can see the + - wires but cannot see which pin they are on the plug or the outlet I will try ohming it from where I.poked the wires.
 

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The solid yellow wire and the black/white wire should have 12 volts with the key in the on position. If I remember right the solid yellow wire has 12 volts all the time. The black/white is ignition power.

The yellow/greed wire is power out to the pump.

The solid black wire is ground.

Did you pull the fuses out to check them? Some times there hard to see if there bad. With the fuses in the fuse box take a test light and touch it to the metal on top of the fuse,both sides should light up the test light if the fuse is good.

The ecu doesn't give the main relay power, it only triggers the main relay to turn the pump on. Without two 12 volt sources to the main relay and a good ground it won't work. The main relay all so won't work if it's going bad or bad.
 

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Discussion Starter #6 (Edited)
I checked the fuses with an ohmeter next I will put fuses in the empty spots. So it sounds like the next thing might be ecu unless I can find a bad ground.I might also try to add a ground to the fuel pump outlet.
 

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You don't need an ecu. You need to figure out why your not getting 12 volts to the solid yellow and black/white wires at the main relay.

Stick one end of wire in the main relay plug of the black wire and ground the other end to a good chassis ground.

Make sure your ignition switch is putting out 12 volts to the wires.
 

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Voltage side of the main relay is almost a straight shot form the battery. Meaning, battery -> fuse -> main relay.

But if you are getting "2" volts, then some of it is going to ground before you can read it. Does the car have an alarm?
 

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Discussion Starter #9 (Edited)
EDIT: did actually turn out to be the computer this time, and some blown light bulbs because of a lot of funky wiring, this car at one time had accessories spliced from almost everywhere. A few new wires/grounds in the critical areas should help also.
 
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