Main relay - 1990 Honda Civic

Check your main fuel relay.



Fuel Supply System


PGM-FI Main Relay


Description


This PGM-FI main relay is located behind the dashboard


lower cover. The PGM-FI main relay actually contains


two individual relays. One relay is energized whenever


the ignition is on. It supplies battery voltage to the PCM,


power to the fuel injectors, and power for the second


relay. The second relay is energized for 2 seconds when


the ignition is switched on, and when the engine is running.


It supplies power to the fuel pump.


PGM-FI


MAIN RELAY



FUEL


PUMP


RELAY


Relay Testing


NOTE: If the engine starts and continues to run, the PGMFI


main relay is OK.


1. Remove the PGM-FI main relay.


2. Attach the battery positive terminal to the No. 3*


terminal and the battery negative terminal to the


No. 2* terminal of the PGM-FI main relay. Then


check for continuity between the No. 5* terminal and


No. 2 terminal of the PGM-FI main relay.


• If there is continuity, go on to step 3.


• If there is no continuity, replace the relay and


retest.



*: 8P CONNECTOR


To FUEL PUMP


3. Attach the battery positive terminal to the No. 4 terminal


and the battery negative terminal to the No.


7* terminal of the PGM-FI main relay. Then check


that there is continuity between the No. 3 terminal


and No. 1 terminal of the PGM-FI main relay.


• If there is continuity, go on to step 4.


• If there is no continuity, replace the relay and


retest.


4. Attach the battery positive terminal to the No. 1 terminal


and battery negative terminal to the No. 2*


terminal of the PGM-FI main relay. Then check that


there is continuity between the No. 5* terminal and


No. 2 terminal of the PGM-FI main relay.


• If there is continuity, the relay is OK;


If the fuel pump still does not work, go to Harness


Testing on the next page.


• If there is no continuity, replace the relay and


retest.



To PCM CONNECTOR


TERMINAL A4


To ST. SWITCH


To GROUND


To IGN. 1 To BAT


To PCM


CONNECTOR TERMINALS


A13 and B1


FUEL PUMP


RESISTOR


FUEL PUMP

The main relay doesn't affect the distributor, the distributor affects the main relay.No spark won't be caused by the main relay.

Try replacing the fuel pump main relay. My 90 accord had the same problem when the main relay went bad, it would take almost 10 tries to start. The Fuel pump main relay is located under under the dashboard on the far left side. The main relay is held in by a 10 or 12 mm bolt. It is small, grey, and says mitsuba main relay on it. replacing this should fix your starting problem. Also check all fuses.
Hope this helps
Matt

main relay.there is a relay underneath the dash thy are culprit of no starts on honda accords its gray in color

I suspect the at this point, the main relay is defective. This relay controls power to fuel and spark circuits.

The PGM-FI Main Relay is actually comprised of two individual internal relays. When the ignition switch is initially turned ON , the Powertrain Control Module (PCM) supplies ground to the PGM-FI Main Relay. This ground triggers one of the PGM-FI internal relays that sends battery voltage to the fuel pump for two seconds to pressurize the fuel system.
When the engine is running the PCM supplies a continuous ground to the PGM-FI Main Relay. The supplied ground keeps the relay in the "closed" position providing electrical current to the fuel pump, keeping the fuel loop pressurized while the engine runs.
If the engine is not running with the ignition on, the PCM cuts the ground to the PGM-FI Main Relay, causing the relay to "open" and stop the electric current flow to the fuel pump. As mentioned previously, if the engine is not running, the PCM will only supply ground to the PGM-FI Main Relay for two seconds when the ignition switch is initially switched to the ON position.
The PGM-FI Main Relay also supplies electrical power to the Idle Air Control (IAC) Valve and to the fuel injectors.

TESTING


If the engine starts and continues to run, the PGM-FI Main Relay is working and does not need to be replaced.

1. Locate and remove the relay.

On some models of the Civic and Civic del Sol it is located to the left of the steering column under the dash. Many later models position it either near the passenger right side kick panel under the dash or by the driver left side kick panel up under the dash.

1. Attach the battery positive terminal to the No. 2 terminal.
2. And the battery negative terminal to the No. 1 terminal.
3. Check for continuity between terminal No. 5 and 4.
4. If there is no continuity, replace the relay and retest

It's going to be your main relay, located under the dash on the drives side, turn key on and off, you will he a clicking sound, that the main relay control your power to you computer also.

sounds like the fuel pump relay is stuck on. find the relay and replace it. hope this helps mike

The main relay is located behind left side of the dash and above and behind the fusebox and above the hood release.

rate this solution fixya.

Diagram below:-

Acura Main Relay location and removal procedures.
Integra EFI Main Relay for:

• Honda Civic/CRX/del Sol 1984-1995
• 1986-89 INTEGRA
• 1990-93 INTEGRA #39400-SH3-003 RELAY (RZ-0063)
• 1986-90 LEGEND #39400-SH3-003 RELAY (RZ-0063) (RZ-0046)
• 1991-93 LEGEND (rz-0105)
• VIGOR (behind the left front kick panel)

The main relay is located behind left side of the dash and above and behind the fusebox and above the hood release. The First generation Legend main relay location is between the steering column and the fuse box. It's deep in there. There was a little difficulty drawing the relay so it's actually very deep in there. There is a device (a relay) blocking the main relay. You will need to remove it to get a view of the main relay. The removal procedure is the about the same as the Accord's procedure.


Legend, 96-98 Acura TL main relay Acura Integra 98-01 main relay location:

Locating the main relay using your ears and fingers:
Steps:

1. Turn the ignition to ON. You should hear two clicks (a thousand of a second apart) under the left or right side of the dash board. One click is for the ECU/Injectors the other is for the fuel pump. At this moment the check engine light should come on.
2. Listen carefully at the moment the clicks engage (usually somewhere underneath the dashboard.) Reach in and touch the main relay.
3. 2 seconds later you should feel a click if the main relay is at least working or wait until it works. At this moment the check engine light should go out.
4. Turn the ignition to start and you should feel a click, turn engine off you should feel another click.
5. Most main relays should have seven terminals. Please check if the location is already listed below.

How do I get the main relay out?
Steps: See four ways below so you can get it out. First you have to reach high up in there and do all this with one hand and a flashlight.
A. Unbolt the bolt using a 10mm socket (picture A) or
Ab. Unclip the clip from the steel tab and slide it apart (picture A) or
B. Separate the steel tab from the plastic case (picture B) with a large flat screw driver jam and twist between the plastic case and the tab or
C. Disconnect the negative battery terminal. Unclip two clips I pointed with two arrows (picture C, or below) with a small flat head screw driver or with a strong thumb and then yank it out (D.) This is the preferred choice by many. Mechanics prefer choice A and maybe B. See detailed relay circuit photo.

main relay contacts get burned up...... common on the hondas its under the drivers side dash

The main relay on 1992 Accords are considered a dual relay. It controls both the ECU and the fuel pump in tandem.