Mazda Rotary Club

General => General Technical => Topic started by: Gerry M on June 04, 2006, 02:58:07 PM

Title: Fuel Pump Resistor
Post by: Gerry M on June 04, 2006, 02:58:07 PM
HI all

Can anyone tell me where the fuel pump resistor is, I\'ve come to the conclusion that its whats causing my problem. As the pump isnt switching over to high speed causing the car to not go above 3k so I\'m going to take it out of the system & jumper it to check. IF this cures it then i\'ll be happy!
Title: Fuel Pump Resistor
Post by: bnaellis on June 04, 2006, 03:30:04 PM
Quote from: Gerry MHI all

Can anyone tell me where the fuel pump resistor is, I\'ve come to the conclusion that its whats causing my problem. As the pump isnt switching over to high speed causing the car to not go above 3k so I\'m going to take it out of the system & jumper it to check. IF this cures it then i\'ll be happy!

It\'s below the brake servo, a little silver rectangle shape device
Title: Fuel Pump Resistor
Post by: sdminus on June 04, 2006, 03:30:16 PM
I think it should still operate even with a knackered resistor.

How i understand it works is. in normal driving the supply goes through the resistor. At high demand a realy close\'\'s which gives the pump full supply voltage.

If i am correct maybe the switching realy is at fault.

Scott
Title: Fuel Pump Resistor
Post by: Gerry M on June 04, 2006, 03:57:05 PM
the relay came to mind as well, & after i did some reading i found that the resistor is for the low speed.
Title: Fuel Pump Resistor
Post by: Prof on June 04, 2006, 05:34:36 PM
It should also have full voltage for cranking to aid starting - so if it\'s not hard to start, then I doub\'t it\'s the relay or resistor.

The idea is that during idle, light load, deceleration the fuel pump doesn\'t need to supply a lot of fuel, so the resistor switches in and drops pump voltage to about 9V.  When you welly it, the relay shorts out the resistor and you should be getting the full 12V.

You could check pump voltages with a meter, or hook a fuel pressure meter into the line and see what you\'re getting.

Best of luck with that one. :cool