what does this resistor do?
 

http://img147.auctions.yahoo.co.jp/u...4105580050.jpg

what does it do? just trying to figure out electronics to check.

If that was located under the master cylinder on the US spec car, it is the fuel pump resistor.

what would happen if it was dead??

the fuel pump wouldent work

I think its the resistor box for the fuel injectors... not the pump. But i could be wrong so flame me if i am. The only way for the fuel pump to not work is by pulling its fuse or cutting its wires.

if this box is dead and is indeed the resistor box for the fuel injectors then when i suddenyl hit boost would this cause backfiring and lotsa smoke coming out the back.. its not boosting correctly, if at all.

here mate,,,,dig through the manual,,,its very easy to test that resistor to see if its broken with an electric meter,, (the resistor changes the voltage to the pump allowing the fuel pump to work at a different speed if im not mistaken).. i very much doubt its your problem,,, but like i said get an electric meter on the connectors.

That is the fuel pump resistor.

Measure the resistance with an Ohms meter. It should be .57 to .70 Ohms at 20 degress C or 68 degrees F.

http://www.iluvmyrx7.com/3rdgen/manu...ol_systems.pdf

(page F 109 in the Mazda service manual)

There is no resistor for the stock fuel injectors. If the fuel pump resistor is unplugged, the pump will not work.

Just a though here, If the fuel pump resistor did fail you would ether have no fuel pump operation or just the low voltage version. In ether case you might have a lean conduction or a really really lean conduction. In ether case its unlikely this would cause a smoking condition. Unless the unthinkable has accrued in that case it would run poor all the time.

I seriously doubt it's bad - they're pretty solid state, and there's really nothing to fail.

And, yes, that is the fuel pump resistor. There's a relay nearby that switches the voltage going to the fuel pump to be either straight to the pump or through the resistor. The resistor drops fuel pump voltage to 9v during idle and cruise.

Dale