Mazda 6 Forums banner

1 - 20 of 33 Posts

·
Registered
Joined
·
23 Posts
Discussion Starter #1
2014 Mazda 6 - turns over and fires and dies. Battery is strong - Key FOB is good and green key is illuminated on dash - I want to test my coil packs for a misfire next.

I hooked up to an OBD2 (cheap one) and it did not populate a code. I believe that I am hearing the fuel pump priming with a slight hum when ignition is on.


  1. Could someone tell me which of the connectors to test on the coil packs and the range of ohms I should look for?
  2. Any other suggestions on what this could be?
 

·
Registered
Joined
·
3,274 Posts
Likely no or insufficient fuel pressure since it fires -- it almost-certainly IS getting spark. When you turn on the ignition you should hear the pump run and it's QUITE audible. If it's a "slight hum" it's almost-certainly broken. After you shut the engine off it runs for ~20 seconds or so as well and again it's VERY audible from outside the car.

No fuel pressure, no run. Note that the fuel pressure is NOT a fixed value either; the pump is variable-output (one of the many things that is "unique" about the SkyActiv design.)

I don't know if you can get the fuel pressure out of an OBD scan tool; I'll see if I can dig it up. Forscan might be able to find it as well; I know the Mazda tool can since there's a spec for it. If the pressure transducer or the wiring to it is faulty that would likely also prevent the pump from operating properly.

Check the fuse for the pump; that's low-hanging fruit and is unlikely to be open unless the pump is dead, but you never know.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #3
thank you for the response. I will check the sound out to be sure. I will also shoot some starting fluid in there to see if it stays running. I agree with the fuel issue. That is what I assumed from the start - There are two fuses for the pump - I need to switch some around to see if that works. Do you know where the transducer to the pump is?
Thanks
 

·
Registered
Joined
·
3,274 Posts
Pull the fuses and ohm them to see if they're blown. If so try replacing it, but if it's blown-blown (e.g. obviously blasted and not just open) there is almost-certainly a short either in the wiring or pump.

If the fuse is blasted and not just open pull the wiring harness before replacing the fuse. If a replacement fuse blows immediately then if you didn't already yank the harness connector do so and change the fuse again; that will isolate the problem to either the wiring or pump itself. If the pump is bad then the fix is obvious; the pump is sort-of expensive but not silly-so.

Be aware that the fuel rail is under a LOT of pressure -- be very careful taking things apart from the pump onward (yank connector on pump and crank the engine to make SURE there's no pressure in the rail before you loosen anything!) and in addition be SCRUPULOUSLY clean when working on that part of the fuel system; one little bit of dirt that gets into the pump or rail and you're going to be buying injectors as well.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #6
thanks when you say the pump - do you mean the internal pump in the tank or the high pressure pump. thanks
 

·
Registered
Joined
·
3,274 Posts
The high pressure pump, since you said you don't hear it running.

There's a whole list of "will not start" possibilities in the shop manual, but if you're not hearing the fuel pump under the hood run when you turn the car on I'd definitely start there (and the relay that drives it.)
 

·
Registered
Joined
·
23 Posts
Discussion Starter #8
Thank you. here is what I have done so far
  • I tested the fuses related to the fuel systems
  • Swapped out relays ( but I will check on the high pressure relay as well)
  • When I sprayed starting fluid in the TB the engine continued to crank and try to start.
Question: Will the high pressure pump still run without sensing fuel - if the "in tank" pump is bad?

also

If I jumper the fuel pump fuse - the pump should run and I should be able to hear it towards the rear of the vehicle - in the back seat or even remove the seat and listen- am I thinking correctly on this?

Thanks
 

·
Registered
Joined
·
3,274 Posts
DO NOT jumper a fuse EVER. If there's a short you're going to burn up the wiring at best and may get a fire or destroy a drive circuit (e.g. in the PCM, and now you're into having to replace THAT!) That'll just add materially to your misery. Either a fuse is good or it's open; if it's open then you need to find out why. They DO occasionally fail mechanically but not often, and if a replacement blows immediately then you have a short somewhere.

I don't know if the high-pressure pump will run if there is no pressure on the low side. There ARE multiple DTC codes that can be set for the fuel system on pressure and also for injectors being open, along with the fuel pump module itself.

I don't know if you can hear the low pressure pump or not. There is a whole laundry list of things that won't allow a start, but if you can't hear the high pressure pump running I'd definitely start with the fuel feed to it and the pump itself since that's almost-certainly the cause. I'd check the main control relay and the fuel pump relays to start with along with both the power and driven side of the relay (you should have power on one pin, show ground potential on the other, and on the one with ground there should be a modest resistance -- neither open or shorted. Be careful not to try to measure ohms across the power lead; that'll blow up your meter!)
 

·
Registered
Joined
·
23 Posts
Discussion Starter #10
Thank you for the response. I took your advice and did not jumper the fuel pump. I am trying to be more aware of the sounds you are describing as well and here is what I did today
  • I listened and heard a hum under the hood with the power on
  • I took out the back seat and I can now hear the fuel pump prime when I turn the car to start.
  • I pulled each of the coils and used a tester to be sure they all fired
  • I also witnesses fuel shooting from the open cylinders when I cranked it without spark plugs
  • Cylinder #1 had oil covering the fire end of the plug which is concerning.
  • I cleaned all the plugs on my steel wheel buffer and reinstalled.
  • I removed the camshaft sensor
Here is my next question.

I pulled the camshaft sensor (one on my 4 cylinder) - found the supply and common and ran an ohm meter on the
sensor alone out of the engine. There is zero resistance between them ( supply and common) - I am hoping that this means that the sensor is a bad sensor.
239899
image.jpg What do you think?

Thank you for the help.
 

·
Registered
Joined
·
3,274 Posts
If you can hear the fuel pump running then it's running, and if you have fuel coming from the open cylinders then the injectors and fuel system in general are working. This means the problem is electrical and since you know the coils are good it's now a question of determining why the PCM isn't firing the plugs.

No signal from the CMT is listed as a no-start cause. Same for the CKP (crank position sensor.)

Your reading looks open; I do not know what sort of sensor that is (hall effect, etc) but if it's a 2-pin then I'd expect a couple thousand ohms as it's probably a simple coil and sends an AC signal when it sees the "tang" pass under it. So with a 2-wire plug, being open is almost-definitely bad and that wouldn't shock me if that prevents a start.

If it's a 2-wire with it out you should be able to put a voltmeter across it on a low range with it out of the car (e.g. 1v or 2v) and then wave something relatively large and steel (magnetic) across the face of it, and see voltage. But if it is reading open on the ohms scale and is a 2-wire I'll bet it's defective.
 

·
Registered
Joined
·
79 Posts
2014 Mazda 6 - turns over and fires and dies. Battery is strong - Key FOB is good and green key is illuminated on dash - I want to test my coil packs for a misfire next.

I hooked up to an OBD2 (cheap one) and it did not populate a code. I believe that I am hearing the fuel pump priming with a slight hum when ignition is on.


  1. Could someone tell me which of the connectors to test on the coil packs and the range of ohms I should look for?
  2. Any other suggestions on what this could be?
Lots of advice going on here, all guessing with out knowing if fuel pressure is being developed or not.
The problem is--"2014 Mazda 6 - turns over and fires and dies". So the engine gets a slug of fuel, starts and dies from lack of fuel, not ignition coils.
The max PSI for the SkyActiv engine is near 3,000 PSI and driven by the engine's exhaust cam shaft, not an electric pump so you will not hear it running.
The tank electric pump only purpose is supply head pressure to the high pressure (HP) pump to prevent it's cavitation. Since the engine starts and shuts down, it seems the tank is where to start looking. If for some reason the screen/filter on the end of the inlet tube to the tank fuel pump gets clogged, nothing you do will fix the car.
Before ripping things apart and damaging anything, I would seek out a test tool to read fuel rail pressure because you have to know, not guess what you are dealing with.
A note on cleaning spark plugs.
Cleaning the spark plugs with a wire wheel or wire brush! Shouldn't have done that if iridium plugs. Iridium is a coating on the spark plug electrodes. It is always wise to check the plug gap before installing but do it carefully with iridium plugs, even re-gapping iridium plugs is frowned upon.
Some Mazda info below.
239909

  • 2014 - Mazda6 - Engine HIGH PRESSURE FUEL PUMP CONTROL [SKYACTIV-G 2.5]
Outline
  • Changes the fuel pressure applied to the fuel injector according to engine operation conditions to improve engine output and startability.
  • The PCM determines the fuel pressure value corresponding to the engine operation conditions based on the each input signal, and drives the spill valve control solenoid valve for optimum control of fuel pressure.
Block Diagram

OPERATION
Directly after engine start

  • During a cold engine start, the fuel pressure is raised to promote fuel atomization.
Basic Control
  • The PCM determines the target fuel pressure according to charging efficiency and performs feedback control by monitoring the fuel pressure in the fuel delivery pipe using the fuel pressure sensor.
    • When idling after engine warm up: Approx. 3 MPa {31 kgf/cm2, 435 psi}
    • After engine warm up, engine speed is 3,000 rpm or more, charging efficiency is 60 % or more: Approx. 15.0 MPa {153 kgf/cm2, 2176 psi}
© 2012 Mazda North American Operations, U.S.A.
 

·
Registered
Joined
·
3,274 Posts
I was with you (likely fuel delivery problem) right up until he pointed out that he checked the camshaft position sensor and (assuming it's a 2-pin connector) it's open. That sensor being inop is listed in the shop manual diagnostic tree as a no-start cause.

He also has noted that he gets fuel spray out the open spark plug holes when cranking with the plugs removed.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #14
Lots of advice going on here, all guessing with out knowing if fuel pressure is being developed or not.
The problem is--"2014 Mazda 6 - turns over and fires and dies". So the engine gets a slug of fuel, starts and dies from lack of fuel, not ignition coils.
The max PSI for the SkyActiv engine is near 3,000 PSI and driven by the exhaust camshaft ,not an electric pump so you will not hear it running.
The tank electric pump only purpose is supply head pressure to the high pressure (HP) pump to prevent it's cavitation. Since the engine starts and shuts down, it seems the tank is where to start looking. If for some reason the screen/filter on the end of the inlet tube to the tank fuel pump gets clogged, nothing you do will fix the car.
Before ripping things apart and damaging anything, I would seek out a test tool to read fuel rail pressure because you have to know, not guess what you are dealing with.
A note on cleaning spark plugs.
Cleaning the spark plugs with a wire wheel or wire brush! Shouldn't have done that if iridium plugs. Iridium is a coating on the spark plug electrodes. It is always wise to check the plug gap before installing but do it carefully with iridium plugs, even re-gapping iridium plugs is frowned upon.
Some Mazda info below.
View attachment 239909
  • 2014 - Mazda6 - Engine HIGH PRESSURE FUEL PUMP CONTROL [SKYACTIV-G 2.5]
Outline

Block Diagram


OPERATION
Directly after engine start

Basic Control


© 2012 Mazda North American Operations, U.S.A.
Thank you for that detailed response. I did not re-gap the iridium plugs - they were all wet with fuel when I removed them with the exception of the #1 cylinder being coated with oil. I ordered a camshaft position sensor and I am going to try it out. - should be tomorrow or so and I will post the results. The car never does actually start - it fires and dies - with each attempt and they are all the same. Starting fluid will keep it cranking but it never seems to "run" meaning firing on all cylinders. This happened in my driveway. Moved the car - shut it off and the next day it was dead. I will acquire a fuel pressure test tool if this new sensor was a mistake but everything I have seen says that the sensor has failed. You mentioned that the HP pump is driven off of the exhaust cam shaft. That's cool that it is mechanical. So if I understand this correctly - the high pressure fuel is bypassed via the spill valve to maintain pressure and gets its signals from the sensors on the left of that block chart. Let me know if I am on track on this but a failing sensor would essentially effect the fuel pressure/delivery?
Thanks again for your time and advice.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #15
Thank you for the response.
If you can hear the fuel pump running then it's running, and if you have fuel coming from the open cylinders then the injectors and fuel system in general are working. This means the problem is electrical and since you know the coils are good it's now a question of determining why the PCM isn't firing the plugs.

No signal from the CMT is listed as a no-start cause. Same for the CKP (crank position sensor.)

Your reading looks open; I do not know what sort of sensor that is (hall effect, etc) but if it's a 2-pin then I'd expect a couple thousand ohms as it's probably a simple coil and sends an AC signal when it sees the "tang" pass under it. So with a 2-wire plug, being open is almost-definitely bad and that wouldn't shock me if that prevents a start.

If it's a 2-wire with it out you should be able to put a voltmeter across it on a low range with it out of the car (e.g. 1v or 2v) and then wave something relatively large and steel (magnetic) across the face of it, and see voltage. But if it is reading open on the ohms scale and is a 2-wire I'll bet it's defective.
Thank you for the response. I ordered a new camshaft position sensor and will advise you if it worked or not. My sensor is a 3 pin which needs power to work. I still had opens in every combination and was seeking a resistance reading between at least 2 - nothing - still open all around. I seen a few videos showing this as a fail so I just went ahead and bought the $30.00 part.
Thank you again
 

·
Registered
Joined
·
3,274 Posts
The HPFP runs off the cam BUT it is controlled by the PCM (the electrical connector on it), so if no signal, well....

The 3-pin sensors have a 12V (or 5V -- gotta check the connector to know which, as getting that wrong will blow it up!) power signal, a ground, and a signal line. Those are usually Hall Effect, but three-wire sensors CAN be digital PWM devices. They can be bench tested once you know which is power and ground if you have the appropriate power supply. It's easier if you have a scope, but a meter will work.

The shop manual does have it (and the crank position sensor) listed as potential crank but no-start causes in the "no start" diagnostic section. The PCM has to know where the pistons are in order to fire the plugs at the correct time; there is no distributor on a modern engine so the PCM gets that information from the crank and/or cam sensors. On some engines they will run (but very poorly) with the cam sensor out as long as the crank sensor works, on other designs both have to be working or you get a no-start.

Keep us posted!
 

·
Registered
Joined
·
23 Posts
Discussion Starter #17
Replaced the camshaft position sensor that I now believe was not the issue. In replacing the sensor, I removed a vacuum hose that I believe goes to the purge control valve solenoid. The engine started - sputtered and smoothed out and ran seemingly rich - smokey exhaust gas odor. When I replaced the vac hose - car died. I understand that this is part of the canister/pcv system. Am I looking at a stuck pcv? or potentially that purge control solenoid. I mentioned in earlier posts that there was oil in the #1 cylinder. Could I be getting too much crank case pressure and blow by in #1? see the pics of the parts I am referencing. It's #'s 17 and 12 in the diagram. I'm not positive of the identification of the parts that I mentioned and could use your help/advice. I looked briefly for the pcv valve - where is this thing? Thank you.
This where it is connected
239939


smokeoil.jpg This is where smoke is coming out of -- "burning oil" -

Diagram # 12 and 17

239941
239943

Coming off of the air intake after the MAF
239944
Not my pic but this is a clean shot of the hose I removed.
 

Attachments

·
Registered
Joined
·
3,274 Posts
The purge solenoid IS listed as a no-start cause....

You have no DTCs, correct? (still?)

Try this (from the manual):
Disconnect hose between the solenoid and charcoal cannister, start engine (since it will run with the hose off)

Put a finger to the solenoid valve -- there should be no vacuum with the engine cold. If there IS Vacuum then it's likely the wiring is hosed or the solenoid valve is stuck open.

Looks like you can remove that solenoid and test it fairly easily; it's 12V and should be open to airflow only when energized (+12V between the two terminals.) If it's open to airflow with no voltage applied to it then it's bad.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #19
Ok cool - thanks for the message. No codes for now and I will do that test tomorrow -

If I am thinking of this right - if the purge valve was stuck open - it would send more fuel to the intake causing a richer burn. It seems to be rich already with the hose disconnected. I am wondering about the fuel pressure regulator sensor and if it is sending too much fuel. At first I thought it was starving for gas but now it needs more oxygen to run. I’m still concerned with the oil soaked plug as well. Don’t know if there would be blow by in all the cylinders if there was pressure built up from a stuck PCV. I’m going to run it tomorrow and try some starts with the purge hose connected. Thanks
 

·
Registered
Joined
·
3,274 Posts
Exactly what the PCM decides if it says "do something" and the "something": doesn't happen I don't know. That decision tree is not published as far as I am aware; it's entirely possible that the PCM could decide that if the MAF reading is implausible due to bypass from the purge valve that it believes is closed is actually stuck open it may decide, with the car out of gear (that is, there's no risk of the driver losing control) to shut the engine down.

The "no start" diagnostic section in the shop manual is surprisingly long for these engines. The purge solenoid is easily tested, which is good; you should NOT be able to pass air through it (e.g. a hose on the easily-disconnected port you can blow into should be enough) if it's not energized. If you can then it's defective.

The PCV on these engines is behind the intake manifold (which makes it a nice pain to change ; the shop manual says that the retainer has to be replaced and not reused and it mounts to an oil separator; it is recommended to replace both as a unit if the PCV is defective. The shop manual says you can check its operation by removing the front end of the hose (at the airhose end) and, with the engine running, check for vacuum at idle. If it's present the valve is working.
 
1 - 20 of 33 Posts
Top