the fuel pump is powered by a main relay, im confused on what a main relay is and how it works. thanks

 

The main relay gives power to the ecu and fuel pump depneding on ignition switch position. When the key is in the ign2 position it gives momentary power to the pump to prime the fuel system with pressure. When the engine is running it gives ign power to the pump and ecu. When the key is off, there is no power.

 

HowStuffWorks has a nice article on relay operation.

 

There are two parts to the main relay. One half powers the fuel pump when the ignition is turned on. (The ECU limits this to about 2 seconds until the engine is running) The other part provides power to the fuel injectors.

 

so, there are two switches in the honda / acura main relay one for the fuel pump and one for the injectors. is this main relay located in the fuse box?

are there any other relays in the car?

 

Relays are just switches that can hold high current. They are used for all kinds of circuits. Cooling fans to rear window defrosters. Its not in the fuse box, there are a couple locations Honda like to put them depending on the car.

 

I know sometimes the PGM relay is located behind the kick panel on the driver side (behind hood release). I also know that these do tend to fail after long periods of time. At least on the older CRX's.

Problem is usually intermittant. Usually no fuel pump kicking when the key is turned on.

But yes the PGM relay either has 2 or 3 sets of contacts inside.

 

Indeed, and mine left me stranded a few times till I figured out what it was. Resoldered the leads and all is well.

On 99-00 civics, this relay is behind the side dash cover on the passenger side.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sackdz &raquo;</TD></TR><TR><TD CLASS="quote">&lt;BLOCKQUOTE&gt;quote:&lt;HR&gt;I know sometimes the PGM relay is located behind the kick panel on the driver side (behind hood release). I also know that these do tend to fail after long periods of time. At least on the older CRX's.

Problem is usually intermittant. Usually no fuel pump kicking when the key is turned on.
&lt;HR&gt;&lt;/BLOCKQUOTE&gt;

Indeed, and mine left me stranded a few times till I figured out what it was. Resoldered the leads and all is well.

On 99-00 civics, this relay is behind the side dash cover on the passenger side. </TD></TR></TABLE>

correction - 99-00 civic, located on the drivers side mounted on the chasis with a 10mm bolt