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peterpete190, Auto Technician
Category: Mazda
Satisfied Customers: 28219
Experience:  Auto repair Technician with 17 years experience.Past ASE and other certifications.
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Symptoms: Cranks but will not start. Firing on cylinder

Customer Question

Symptoms: Cranks but will not start. Firing on cylinder 1-2-4 once during each start sequence. Will not fire again no matter how long you crank it. Cylinder 3 is not firing at all.
History: Original engine threw a piston on cylinder 1, smashed plug and cracked housing. Engine was replaced with a new short block and components swapped over. New engine would not fire.
Checks: Replaced camshaft and crankshaft sensors and wiring harness. Engine then began firing once as stated in symptoms above. No error codes at that time.
All coils have 12V and 5 V at connectors. All coil resistances are per the manual (resistance check). Replaced all plugs.
Checked all fuses and relays.
Checked camshaft timing and checked crankshaft pulley setting.
Checked fuel pump relief valve (not blown).
Security light illuminates and then goes out.
Fuel injector resistance is per spec.
Changed main wiring harness and coil harness.
Compression is within spec per manual.
VVT sensor was checked in spec per manual
PCM was sent in and tested. No problems detected.
Changed one coil that had different resistance readings that the other 3, not sure it was bad.
Checked about ten other components, all within specs per manual.
Fuel pump is running. Fuel pressure is 65-70 psi, but not higher during cranking.
RPM are 250 rpm or so, while cranking. Battery is over 12 V.
All checks and attempt to crank are with turbo cooler removed from engine.
Trouble Codes: After replacing the camshaft and crankshaft sensors, there were no error codes. It was recommended to send the PCM in to check for damage due to the original engines damage to cylinder 1 plug. When the PCM was reinstalled, I now have error codes P2127, P0107, P0192.
Found out tone wheel on intake camshaft was missing. Replaced w new.
Now fires only on cyl 1 and 4. Getting codes P2127 and P0091. Fuel Pressure reading is 0 psi but still runs like it’s in limp mode. Checked compression which is good and checked all cylinder – all firing. Pulled ignition wiring from all cylinders while running – when pulling 2, and 3 got no change in engine speed, but pulling 1 and 4 killed the engine. Checked injector resistance- all good pulled injectors and fuel rail to look for trash. Nothing visible. Checked all wiring back to PCM, no issues.
Sent PCM in for analysis – no issues
Cleaned all injectors, all spraying good. Still getting P2127 and P0091 and no fuel pressure reading on gage. Sprayed starter fluid directly into throttle body….ran well for a few seconds.
Rechecked fuel pressure at HP Fuel Pump inlet – 65 psi….good flow
Removed inlet to fuel delivery pipe before injectors….good flow.
Appears to not be getting fuel at a high enough pressure for injection in cylinder?
Need diagram and part number to rebuild HP fuel pump
Submitted: 1 year ago.
Category: Mazda
Expert:  peterpete190 replied 1 year ago.
My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.My info is somewhat limited on your model here but I had seen no one else has responded and would like to see if I can help here.If at any time you feel that I cannot help with this please let me know. You may have a fault here with a restriction in the fuel supply line or system or the fuel pump itself at fault needing replaced.If you can post the year and model as well as engine size for this vehicle here this will help just let me know. If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.Thanks Pete
Customer: replied 1 year ago.
2007 Mazda CX-7 2.3L Turbo
Expert:  peterpete190 replied 1 year ago.
O.k.,unfortunately my info is limited on this model here myself.I will open your question up for others here to see if someone else can assist further on this as there may be others here that may have more info on what to check or do with this issue.I hope you can get this resolved with ease.No need to reply to my last post here unless it is a last resort as it will keep your question locked to me and others will not be able to view it.If you feel you want to continue to work with me on this feel free to reply at any time but keep in mind in some cases it can be difficult to fully diagnose or help repair this without seeing your vehicle.Thanks Pete