No Fuel to Engine, need guidance.

[Philip Parker]

So I got back from our extended trip this summer and my GTX wont start. There is spark, but no fuel at the fuel filter on the firewall. Here's what I've got so far:

The Main transfer pump under the passenger rear floorboards does make noise. 

The voltage to the Driver side transfer pump is 12v.

The voltage to the passenger side transfer pump is 7.6

The car is reading just under half a tank but will not take any more fuel. It kind of seems like the in tank lift pumps aren't coming on. 

I pulled fuel the  pump module from under the driver seat and cannot find a part number for it. Any one ever replace on of these things? It's my current guess as to what is going on given the voltage reading at the connector for the passenger side lift pump.  

Any help is appreciated. 

Thanks!

[Daniel Roy]

Passenger side pump is only there to transfer fuel to the driver side. If you have fuel on the driver side then even if the transfer pump doesn’t work the car should start.

There is a yellow jump connector right beside the battery you can use to get the fuel pump on. Jump it like in my picture and see if the pump starts. If not then either your pump is bad or the wiring to it is.  

Dan

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[Philip Parker]

Yeah I had that jumper installed to hear the transfer..so the main pump is in the driver side tank I assume?  

[Daniel Roy]

This jumper starts the main fuel pump not the transfer. The transfer is controlled by the module under the driver’s seat and a float switch in the tank. When fuel in the passenger side of the tank is over a certain level the pump starts and transfers fuel to the driver side until the level goes down to a preset level. This is why when the tank is full the transfer pump runs continuously. The module only use is to act as a buffer to prevent the pump from starting and stopping repetitively when the fuel is near the switching level and fuel moves around when driving. 

So when you turn on the ignition without this jumper if you hear a pump it is the transfer pump. If you jump the yellow connector you will hear the main pump coming on. If you “unjump” the yellow connector the main pump will continue running until you switch off the ignition. Same thing happens if I hit the start position on the ignition switch, even if the engine doesn’t start, I hear that the pump continues to run.

At least this is how mine has always been for the last 18 years. Always found it a bit odd to react like this as in case of an accident the pump would continue to run, potentially feeding a fire. Usually when no airflow is detected the pump should stop. Anybody else wants to chime in on this?

Dan

 

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[Daniel Roy]

Hi Philip,

According to the manual and wiring diagram, the yellow connector will only start the main pump, not the transfer. The transfer is started and stopped by the transfer pump switch (a float in the tank separate from the sender unit). If the fuel level is high enough, the transfer should start on it's own after the ignition has been on about 10 seconds (delay induced by the pump control unit).

On the main pump, at the vehicle side connector, you should have 12V between ground (black wire) and green with red stripe wires (there are 2 wires and both should have 12V) when ignition is on and yellow connector is jumped. There is another single connector with black wires, those are additional grounds for less resistance, same as the dual 12V+ of the green red wires. Mazda chose to double the wires for additional current carrying capacity. If you want even better available current for the pump you can run a fused 10g wire from the battery + and switch it with the original wiring and a relay, I did this back in the day. If you have 12V at this connector, pump should run. You can test the pump by sending it current directly from a battery. If pump doesn't run, pump or its wires are bad. If pump runs then you probably have a problem somewhere in the wiring. You can have 12V showing but too much resistance in the wires so that the wire can't supply enough current to run a high current item like the pump.

I had a similar problem with my cooling fan where I had 12V showing at the fan but it wasn't running. The contacts inside the fan relay were oxidized, letting enough current pass so my test light and voltmeter were showing 12V but not enough to turn the fan. I opened the relay, sanded the contacts and the fan came back to life. If you see 12V at the connector, have tested that the pump runs on direct 12V but doesn't run when plugged in the connector you can check the contacts inside the "Circuit Opening Relay" in front of the center console right beside the ECU.

I hope this will help.

Dan

Le dim. 1 nov. 2020 à 22:50, Daniel Roy <danr...@gmail.com> a écrit :

Yes you have your pumps right. You only the drivers side pump to get the engine running. If you don’t hear the pump coming on with the jumper I think you have a problem there.

I’ll check my manual tomorrow to see if I can find anything else. For now, time to go to bed!

Dan

Le dim. 1 nov. 2020 à 22:38, Philip Parker <philiptho...@gmail.com> a écrit :

Gotcha. So my manual is calling the pump that is external to the fuel tanks and under the passenger side floor board the transfer pump. It is also calling the pump that is in the driver side tank the fuel pump...does that sound right? 

If I have the jumper out I get no pump noise anywhere. If I have the jumper in all I get is that external transfer starting after a few seconds of key on. If I understand you correctly I should hear the main pump come on with key on in the driver side saddle under the rear seat correct? Thanks for your help, the manual is kind of vague on this. 

Philip

[Joel Sass]

Hey Philip,

I had the "reading half full" problem on my car when I bought it. It turns out that it was the transfer pump on mine - the vehicle shows fuel based on the levels in both tanks, which is measured by a float on both pumps. If one of your pumps is not properly measuring fuel, and you've got a full tank, this is the result: it will show half full.

I'm suspecting a main pump failure at this point. If you're not getting fuel to your filter, but spark is firing, there's only a couple things it could be: a line failure (I've had this happen too, but you can smell fuel dumping easily), or a pump failure.

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[Terrence McGrew]

I'm resurrecting this post from the dead.   My car lost power on the highway and I had it towed home.  It will crank but not start.  I no longer hear the xfer pump nor the fuel pump.  Both of these were replaced in the last couple of years.  I ended up at the Circuit Opening Relay and was testing for power at the pins with the car ON.  I got nothing but 0V except for 2.5V at FP pin.  The relay was tested per the FSM and the resistance is in spec across the pins.

Any ideas?

Terry McGrew

Santa Cruz, CA USA

[Joel Sass]

So that I understand: when you apply 12V to the relay, does it close properly? And when it closes properly, can you see continuity across the closed switch? This is sounding like a relay/wiring issue. Oh, also: how does the ground for the ECU look?

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[Eric Neves]

I had a similar issue with my fuel pump getting no power. Traced it all the way to the fuse block, no power to the whole back of the car. Mine has been sitting for years since i dont know where to get a new fuse block

Sent from my iPhone

On Aug 22, 2025, at 14:38, Joel Sass <sass...@gmail.com> wrote:



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[Terrence McGrew]

I did not hear/feel the relay activate when I turned the key ON.  With the relay connected: I put the DVM leads in the connector per the FSM and got basically no voltage across the pins it said to test.  I removed the relay and put the DVM on it to check resistance per the FSM and it tested good.

--

Terry McGrew
Santa Cruz, CA. USA

[Terrence McGrew]

OOF, I hope you fix it!

[Cody Vallon]

I had a crank no start happen to me. Same scenario, unded up being the turbo inlet pipe support bracket bolt fell out and the inlet came off the turbo. It wont send power to the fuel pump without seeing airflow come across the maf. Something to check.

To view this discussion visit https://groups.google.com/d/msgid/323gtx/BDF2EC7C-9ACB-4612-A896-570DFE5DB8B7%40yahoo.com.

[Jason Culligan]

A bad airflow meter will cause this exact scenario. You can use a meter to check resistance across two pins while moving the flap. I don’t remember which two pins right now. Hope that’s at least a little helpful. 

Jason Culligan

560 E Parkland Ave 

Evansville, IN 47711

812-319-2840

On Aug 22, 2025, at 7:54 PM, Cody Vallon <cvall...@gmail.com> wrote:



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[323gtx]

So that I understand: when you apply 12V to the relay, does it close properly? And when it closes properly, can you see continuity across the closed switch? This is sounding like a relay/wiring issue.

[Bob Martin]

Once you jumper the test connector, doesn’t it bypass the MAF safety cutout and run the pump all the time? If he has no voltage at the test connector, then the problem is upstream from there.

One test would be to hot wire 12v to the test connector to see if the pump runs then.

Bob

Sent from my iPhone

On Aug 22, 2025, at 7:40 PM, Jason Culligan <fit2...@gmail.com> wrote:

A bad airflow meter will cause this exact scenario. You can use a meter to check resistance across two pins while moving the flap. I don’t remember which two pins right now. Hope that’s at least a little helpful. 

To view this discussion visit https://groups.google.com/d/msgid/323gtx/A7F5DD2D-A93D-4D1D-8148-CF67E5813E43%40gmail.com.

[Terrence McGrew]

During troubleshooting, I put a jumper in the test connector and the pump didn't turn on.  I forgot to mention that.

Terry McGrew
Santa Cruz, CA. USA

[Joel Sass]

When you jump the connector in the photo, and then turn the key to "on", the pump should start immediately. If it does not, the FSM is stating that you need to check voltage to the fuel pump. It's possible that a wire broke, or the pump has gone bad. The good news: replacing the pump on these cars is super easy because the manufacturers were smart about putting in access panels under the rear seat. Thank god.

-- Joel

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[Terrence McGrew]

UPDATE:

It was the dang 15A fuse.  I pulled it the first time and I guess I didn't see it too good to notice that it failed.  That explains why the Check Engine Light was not illuminating and the test connector didn't turn on the pumps when shorted.  I feel dumb.  I did end up getting a new ignition switch to remedy the "click-click" issue.  

SPEAKING OF:  Does anyone have the write-up to install the pushbutton starter on the gauge cluster trim below the gauge light dimmer?  I have an old push-to-hold button switch and the write up shows how to turn that p2h switch into a momentary switch.  If I remember, it was by Kenny Lew from years back.

Thanks,

Terry McGrew

Santa Cruz, CA. USA

[mfel...@gmail.com]

Nice find!

Here is the write up:

http://web.archive.org/web/20050208183455/rxtrme7.aaph.com/gtx/starter_button.html

Cheers

Mark

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[mfel...@gmail.com]

Iirc i have the full page saved for the images if needed

[nowi...@yahoo.com]

I replaced the ignition switch on one of my cars, and the clic click is still a feature.  I am believing that it is needing a new starter.  Are starters still available?

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[Marc Feigitsch]

Could that be a worn out key as well?

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[nowi...@yahoo.com]

I don’t think so on the worn out key.  The feature of click click works with two different keys. 

 

I have not replaced the starter on this car yet, and used my last new starter on the other car, and it turns over so nicely now….although the other car had a bendix spring release issue and was different – so don’t want to use that old starter.

[Terrence McGrew]

The starters can stil be had (remanufactured and new) at rockauto.com 

[mfel...@gmail.com]

Hey all,

I cannot immediately find the saved html page.  If I locate it, I will post it up.  

From Greg D.

"If you are getting the click-click-click when turning the IG switch. This

issue can be the clutch switch, backup light sensor, IG electrical portion.
First off I would clean the connector on the BUL switch, this seems to cure
some of the starting issues.

Most, however do the IG mod that puts a push button starter switch on the
dash and by pass the old wiring to the starter."

I did the bypass as well and never ran into any issues.  I think it still turned out to be a stuck starter solenoid for me lol

Cheers,

Mark

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