Hi all! My 2007 Mazda Tribute V6 broke down a week ago. I filled it with petrol, stopped on way home for 15mins to get food - then when I went to drive off, I got 50 metres and it stalled. When I tried to restart - it would start but died again as soon as I pushed on accelerator. Repeated attempts made no difference....it idled (roughly) but when accelerator was applied even slightly, the engine spluttered and stalled. (It was a very warm evening, but car hadn't overheated)
RAC check brought up 'running lean' codes. Car had to be transported home.
At home next day when engine was cold it idled rough for a few secs but died every time accelerator applied. While checking/working on engine and using 'Start Ya Bastard' it started to idle more smoothly but still cut out on acceleration.
Used OBD11 Tester which showed 02 Sensor Codes P2195 and P2197 (see attached images)
I changed all 6 spark plugs (as they were due)
Checked the vacuum lines for leaks (plus connections) & replaced some that were starting to perish.
Also checked EGR valve by blocking off but made no difference.
Examined as much of engine as I could for anything else that could cause vacuum leaks.
Also replaced the fuel filter.
I put a fuel pressure gauge on the Schroeder Valve near the fuel rail and was initially getting 60psi, but the fuel pressure dropped to around 30psi after the engine warmed up.
The confusing thing is - the fuel pump comes on with the ignition, it appears to come up to pressure and stops as it should after about 3 secs.
Also, when I activate the Schroeder Valve with the ignition on, it releases the fuel pressure, but the fuel pump doesn't restart.
NOTE: I can clear the O2 Sensor codes when the engine is idling smoothly, but it still stalls when I press the accelerator.
Question:
I can't locate the fuel pressure regulator. Is it built into the fuel pump? (I can't find a return fuel line on the fuel rail)
How does this system work in the 2007 Tribute?
Or could the fuel pump itself be faulty?
Desperate for ideas please. Am on a budget and have dependent family member with a disability so it's really tricky without a functioning car.

 

Hey there man. Great info in your post above. I cant speak for the 07, but on the 03 the pressure regulator is right by the rails, under the throttle body if memory serves.
I'm not savvy with reading fuel pressures to know what they should be. Were I in your shoes (I'm halfway there - disabled family member and financially uncomfortable) I'd examine the injectors since that's not too terrible.. You can, for a few seconds, jump battery power to them individually and listen for a click. You can even pour or blow some fuel into them when energizing to observe the spray pattern - though the surgeon general may have some negative remarks about that practice. you just pull 'em and make two jumper wires (preferably with female mini quick disconnects on the injector terminals so as to avoid shorting sh*t.) Since your fault codes are banks 1 and 2, but both sensor 1.. I'm pretty sure that's pre-catalyst. so I think you're heading the right direction checking out fuel, air, spark.

Taking the intake junk off down to the injectors will also provide opportunity to examine vacuum connections and gaskets more thoroughly for any sort of goof-baggery.

If there is no visible pressure regulator, it may well be integrated onto the fuel pump (as is the case with my 2012 honda fit). Fuel pumps aren't too costly or hard to swap out, but.. see below.
Some questions: What's weird about the fuel pump coming on and shutting off when you turn the key to ON II and don't start it? Maybe I'm misunderstanding, because that's standard business.

And as for attaching the pressure guage to the rail, are you saying it looses all pressure and doesn't kick back on? Is the key in ON II with the engine off when this happens? I know the pump comes on with the key to pressurize. I do not know if it's smart enough to re-pressurize if that pressure gets dumped before start up without turning the key off and back on again.

I wouldn't jump on the fuel pump if you're consistently hearing it come on and it starts the car repeatedly without issue (following re-pressurization.)

Have you or anyone else done any work on it prior to this fault? What was the last job done prior, and is there any other junk going on that we might benefit from knowing about?

It sounds like stuff is tense over there. If you can help it, don't let it make you jump the gun with your diag. Rushing into these things too often winds up hurting more, even though it's hard to chill when responsibilities are piling up. I hope you're alright and that I hear back from yuh, particularly if the problem is persisting. Feel free to pm or whatever.

 

Hi,
Thanks for your input.
I eventually nutted out the problem after being led astray with my brand new fuel pressure gauge being faulty making me think I had a fuel pump problem. After eliminating the fuel pump, I studied the output from all the various sensors using my OBD2 tester and found that the MAF sensor readings didn't seem to change, but as I could not rev the engine above idle, without it stalling, it was hard to confirm. I did notice that the MAF output remained constant (the same reading as at idle) even when the engine was not running. I decided to confirm this by squirting some Start-Ya-Bastard into the intake and getting it to rev up for a brief moment but the MAF output still remained the same. I then thought to disconnect the MAF connector to see if this made any difference. The engine then burst into life confirming the sensor was faulty. I ordered a new one and fitted it and problem solved! Thanks for all the support.
Blessings John

 

An actual bad MAF! That's outrageous I swear at least 90% of the people I talk to replace their MAF sensors while troubleshooting only to find the original was perfectly fine. Think it's a carry-over from folks being uncomfortable with electrical because they don't understand it as well.

I'm stoked you figured it out! Good on you!