Ok I know where the Relay is but cant seem to find the resistor by comparing it to my manual.

I get resistance on the meter when connected directly to the fuel pump connector but not hearing it go on when the ignition is turned on. I'm trying to trace it.

 

under the master cylinder...looks like a heat sink and has a two wire connector.

 

can someone explain exactly how they rewire their fuel pumps? do you cut out the resistor there or do you just run a new wire from the fuel pump to battery?

 

^^ Good question. I cant get my fuel pump to work at all and not sure what else to do

 

couple ways. You can cut the resistor "box" off and use the connector as a jumper. Two leads spliced/solder together.

or make your own jumper and connect it to the harness side, if you don't want to cut the resistor off.

Talking with Cam at Pettit, they make the jumper for the speed relay, so the resistor is always bypassed. Some people modify the relay so it's always making contact.

Note for those who don't know how the system works:

idling and crusing the fuel pump relay makes contact and sends voltage to the pump via the resistor ~9V or something. LOW speed.

Once you start making boost or a selected rpm (can't remember if it's rpm actuated also), the "fuel pump (speed)" relay makes contact and by passes the FP resistor and sends full voltage ~14V to the pump. HI speed.

either way the pump will get full voltage all the time. This could cause a need for a little tweaking to your idle and cruising maps, since the pressure will be bumped up in these ranges and run a little rich.

 

I pioneered the fuel pump rewire on the FC ages ago. The TurboII's also had a 2-speed fuel pump system.

Has anyone checked the voltages to the fuel pump on the FD? The main reason for rewiring the fuel pump on the FC was to get the voltage where it should be. On my old FC with a VERY healthy electrical and charging system, I would get around 11 volts and sometimes less at full throttle with the AC going, stereo going, lights on, etc. BIG voltage drop. After rewiring it with a relay and wiring straight from the battery, I got 14v MINIMUM to the fuel pump under full throttle, regardless of electrical load, and switched back to low voltage while cruising.

There's some speculation if you really need the dual-stage feature. I don't know if Mazda did it primariliy for noise or for fuel pump life. Considering I've YET to see a stock fuel pump fail, I'd reckon it was more for noise.

A fuel pump that's wired hot shouldn't make the car run much richer - it will increase the flow of the pump, but the fuel pressure regulator should take care of the fuel pressure. If you rewire a Walbro or the like, you may have issues with too *much* fuel pressure - I did on the FC. I got an aftermarket FPR that let me dial the fuel pressure where I wanted it.

Dale

 

I'm curious on how to rewire the resister myself. I'll be running an aftermarket FPR, so I wouldn't have to worry about too much pressure I would think. I'l like to get the most out of my Competition fuel pump. Any pics or write ups?

 

Could this resistor be stopping my fuel pump from comming on?

 

doubt it but the relay may not be closing

 

Is there anyway of testing this relay and if so than how... I have a meter but not sure what to look for.

Funny thing is that I cant hear the fuel pump noise listening thru the tank when the key is turned on.

I smell fumes when cranking the motor.

I get spark.

Plugs are dry

Car doesnt even sound like it wants to kick over when cranking.

Everything ran fine the day before.

I did what the manual says for checking resistance on the fuel pump connector which im getting so the fuel pump should be good. I just dont know

 

are you getting voltage on the w/r wire at the fp connector? the w/r wire turns into a l/r after the resistor does the l/r have voltage?

 

Can you explain this a bit more to me.

 

Ok... Fuel pump Relay looks fine, I removed the cap turned the ignition and watched it close and than open when the key was turned back off.

I pulled the fuel line going into the motor which the fuel drizzles out (car on an incline with gas tank up top), turn the key to ACC but I dont get any added pressure from fuel pump, crank the motor with same results.

My question is am I right in thinking that this points to the fuel pump? Also how should I test it to see if it is definately bad?

If pump is bad which one should I replace it with?

Thanks for helping and dealing with my troubles

 

put a jumper inbetween the fp and the gnd terminal. unplug the fp connector. see if you get voltage at the connector. if voltage is ok pull the pum and see what is going on. wire loose, cracked rubber pump to fuel assembly hose, or a bad pump. with the pump out you can use a set of jumper wires and a car battery to see if the pump will turn on outside of the car. if that is all ok the fuel filter may be plugged. glwi

 

I have a stock one I'll sell cheap...~40k miles

 

Once I figure out if it is the fuel pump I'll let you know. You can pm me a price.

 

I disconnected the fuel pump and attached my meter to that connector, turned the ignition on and jumped the FP and GND terminals and I get 2.93 on the voltage meter and I also hear the Circuit Control Relay making a noise at the same time. But when I jump the terminals and get the 2.93 on the meter it only last for a second and than counts down to zero. Is this normal for it to do this? If this normal than tomorrow I will folow your steps in pulling out the pump and checking/test it.

Anything else I should be looking for?

 

If you jump F/P and GND on the diag.port, then you should read 12V at the ignition ON. During the driving, regardless of those terminals jumped or not, you should read around 8V under light load and 12V under high load. At least this is how it works on my FD.

 

Yeah but should I be receiving 12V to the fuel pump? I'm only getting 2.93V comming through that wire to the pump.

 

Yes, that are the voltages you should be receving at the F/P and you can read them at the F/P connector. IIRC you should measure the voltage at the two thicker wire coming into the connector: white/red is positive, black is negative.

 

Damn.. So why would I get the voltage I'm getting and where should I look for the problem. Thanks for all the help