Stumbling, rough running, stalling, now no start

S

SpeedyThrees

Greenie N00B Member
Greenie Member
Performance degraded rapidly from running perfectly, then stumbling, then barely running, then stalls, then starts but barely running, to barely starts, then to no start.

Back story.
2012 Speed3 - all stock except for junky Corksport Cold air intake and Catback exhaust
Car sat for 2 years with burned cylinder head.
Replaced cylinder head, timing and injector seals.
Initially had a no start problem that turns out was just simply stupidity. Link here, https://mazdaspeeds.org/index.php?threads/new-head-no-start-runs-on-starter-fluid.17540/

Stupidity resolved, car ran like a top on the jack stands under front only. I mean, balance a nickel on it smooth.

Took car for 5 mile test drive, ran flawlessly, then within 30 seconds went from stumbling to barely running, to stall.
Car sat for a couple hours, started up and ran just fine. Took for test drive, went 1/2 mile then the same degradation into stumbling, barely running, stalling. Each restart attempt yielded less and less willingness to stay running and eventually no start.
Car sat for 30 mins, started but running rough. Drove 1/2 mile home.
Car remained idling roughly in the driveway but with loud clacking and squealing from HPFP area.
Code reader showed only P0300 and approx 1000-1400 psi at fuel rail at 2k rpm.

Suspected HPFP failure, replaced with known good one. Inspection of cam cup, cam lobe and internals of removed HPFP showed no damage.
Start engine, idles very roughly but no clacking or sqealing.

Suspect water in fuel. Follow me here. Car sat in driveway for 2 years, plenty of time for condensation to build up. After rebuild, while on jack stands under the front, removed as much fuel as I could via HPFP inlet and cycling the fuel pump. Replaced 5 gallons of fresh 93. My theory is that when car was on stands, the water moved to the back of the tank and was not removed by the fuel pump. Then with car on level ground, the 5 mile test drive was enough to for the fuel pump to pick up the water and deliver to the engine causing my issues.

Fuel sample taken, 12 oz from HPFP inlet. Water in fuel confirmed. Approx 1/2 ounce in 12 oz of fuel. Add a bottle of water remover to fuel tank, shake vigorously. Cycle fuel pump until fuel samples at HPFP inlet are clear.

No Start, just a few putt putts. Suspect water still in fuel rail. Remove rail pressure sensor. Cycle HPFP to pump clear fuel trough the rail. Replace sensor. No start, just a single putt. Code reader now shows 0 psi in rail during starting attempts

Current status
New head and timing, approx 175psi all 4 cylinders
New injector seals, new OEM spark plugs at .027, fresh fuel.
60 PSI at HPFP inlet. Known good HPFP
Brand new battery supported with autoshop level battery charger with Starting boost
NO START, Just a single putt on every attempt.
Fuel rail pressure shows 0 psi during start attempts.
Only have a decent code reader, No access port or high end diag tool.

Suspected MAF damaged from starting fluid use after initial rebuild. Disconnected MAF, no start.
Suspect failed Pressure relief valve.

New MAF ordered.
Mazda will not sell me a new relief valve. Says that that part says not serviceable and only available as complete fuel rail unit. $1,000. haha.
Market is rife with pressure relief valves, but I've read so much conflicting info on which part number to get, not sure what to buy from whom.

Is this degradation of performance indicative of FPR failure?
Can FPR be tested on cold non running engine? Is looking for any fuel coming from FPR on cranking a valid test in this case?
If FPR is condemned, please confirm what part number and source I should procure from.

So grateful for any input that you may have on this scenario.
 
OK. Will do.
But HPFP was already replaced with known good one during this saga. There was was no change in performance.

Also, does that instruction indicate that you do not suspect a relief valve failure?
 
Cleaning is free is why I would start there
 
Disassembled HPFP and cleaned. Relatively unremarkable. Black and dirty, little bit of caked on crust here and there. Plastic inlet filter was all but blocked with varnish, replaced with Corksport stainless screen. Reinstalled HPFP

Attempted to start. Same result. Just a few putt putts. grrrrrr.
Frustrated, I sprayed some starting fluid in the boot near throttle body. Same result, just a few putt putts, with throttle closed or wide open. Same result with Injector relay pulled. I have compression, oxygen and certainty of fuel with starting fluid. Only one things left.

I pulled my brand new NGK plugs to discover them completely carboned over. A 5 mile test drive had fouled $80 in plugs. Upon inspection, discovered that I paid for the correct plugs but was handed the wrong plugs. I went and purchased a new set, installed them and the car fired right up. No problem. Still some chirping coming from FPRV. I have a new one on the way.

It really is amazing the variety of reasons why our toys give us headaches. 35 years of working on my own cars and this is a new one for me.

Vroom Vroom Zoom Zoom again. Yay

Thank you again for your attention and suggestions.
 
Where the hell are you that spark plugs are that expensive?
 
30 miles NE of ATL
NGK Iridiums from Orielly's
17.99 each x's 4 + tax ='s $77
 
Last edited:
UPDATE - Solved

After days and days of an enigma of a Speed..... Start it in the morning, runs like a top, drive it 1/2 mile and it strands you with misfires, stalling and no starts, plugs covered in carbon. Sits for a few hours, might start and barely run, might start and run like a top, might not start at all. watching fuel rail pressure live would show 430-500psi at idle when running well, dropping to 175psi when running crappy, chirps and squeaks from the Relief valve that matched the misfires and then not starting at all with rail pressure at 80 psi. Start the car tomorrow and rail pressure is stable at 430psi at idle, turn the car off and watch rail pressure climb as it should. try to start it immediately after that and no start. Grrrrr.

After multiple HPFP rebuilds and swaps, replacing fuel pressure relief valve and new spark plugs a few times.... I did another relief valve test. Car started, ran well, warmed it up, watching rail pressure steady at 430 psi again, turned it off, no start, rail pressure indicated 70 psi and dropping, 40, 28, ZERO. no start. rail psi holding at Zero. I found that hard to believe, went to remove Fuel rail pressure sensor and high pressure fuel sprayed out of the threads for minutes. That certainly is not ZERO psi.

Ok, condemn the Rail pressure sensor. Replaced it with a known good one from another speed. It's a 1 minute swap. Car started right up, steady rail pressure and solid FPRV test after. Sensor failure confirmed. When the sensor got warm, readings would degrade to zero.
Stock sensor is Bosch 0261545058. Mazda will not sell it to me, only available as part of the fuel rail fro $1000. grrr This sensor is a unicorn and is not in any AutoParts stores. Can buy it online, but that does not get me running today.
Bosch 0261545038 IS available in parts stores for $75. This sensor is also used in Ford DI engines. It may have a different min and max range, but figured it would get me running. Car started right up, rail pressure steady at 430psi, max that I saw under boost was 1700+, but didn't do many pulls and not very hard. Seems to be working fine. But, I do have 2 0261545058 sensors ordered, just in case this "...038" gets wonky, I will swap in the oem "...058" sensor.

I hope that this accounting of my struggles serves as a public service announcement for others with strange misfires, no starts and inconsistent rail pressure issues.
SOLVED
 
same symptoms on my mazda 2 2019. only difference was, my sensor was stuck at 29900 kpa always even with engine not running. its was stuck in range, so fuel pump did not prime . car cranks but no start. was the stupid fuel pressure sensor. took me days to find the issue. only problem is , I cant find the sensor separately 0 261 545 155. the Stealership wants to sell me the complete rail.
 
Fritz said:
...The Stealership wants to sell me the complete rail.
Click to expand...
Correct. Junkyard it and hope for the best if you're tight on funds, though maybe someone else can chime in with other advice if there's a replacement part number that's compatible.
 
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