My 2016 CX5 recently started missing and running very rough and after taking it to a Mazda dealership, they diagnosed it with a bad high pressure fuel pump. I intend to do this job myself as it looks pretty simple. I have not found much information on this job online but I did find what looks like to be a service manual excerpt covering the procedure. In this document it indicates that the engine needs to be manually positioned at 90 degrees past top dead center. Has anyone done this job and can speak to why this is necessary? Thanks

 

What did they do to diagnose a HPFP problem? Is the CEL on? Is there an OBD code set which indicates an abnormal fuel rail pressure? Did they note on the paperwork and/or tell you that they did a low pressure (in-tank) fuel pressure test, showing that the LPFP is good?

 

Yes there is a CEL on for a P0192 - Fuel Rail Pressure Sensor Low Voltage. They did admit they had a tough time diagnosing the problem but after checking everything through they actually swapped over a known good HPFP and the problem went away.

 

Here you go, high_pressure_fuel_pump_removal_installation-1500.html

 

That is the service manual excerpt I was referring to. Notice in the installation section it says to rotate the motor over to 90 degrees past TDC. That was really what my question was about.

 

Yep, throwing a working pump, and possibly also a high pressure sensor (fuel rail) on is basically the only way to diagnose that code (although I'd always do a LPFP pressure test first).

The crankshaft rotation is done to put the exhaust cam in the preferred position, in order to avoid possible damage to the HPFP on the initial startup. Hopefully you'll be replacing the high pressure pipe, along with the HPFP., instead of reusing the factory pipe.












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I had planned on trying to reuse the factory pipe, the service manual excerpt from above states it can be reused up to five times. I did think about going ahead and replacing it though. Do you have any instructions or getting to the nut on the fuel rail side? It looks like the throttle body and intake manifold may need to be removed.

 

There's nothing in the FSM about removing the TB and manifold, just the air box plumbing. And my CX-5 is a second gen with a different engine, so looking at mine, to try helping with your access issue, might just send you down the wrong path.

That 5X reuse of the pipe on the first gen is weird IMO, particularly since the Mazda second gen FSM specifies that the pipe should always be replaced. I can't imagine how they determined that it could safely be reused 5 times, but no more than that. With the HP fuel system creating pressure over 3000 PSI, I'd never reuse one of those pipes. But as always, your vehicle your choice.

 

No I understand. I thought the 5 time rule is odd myself. I think I may be able to get it with a box end wrench or flare nut wrench but not a crows foot. I see the torque spec of 18-25 ft lbs so I’m not sure how I would get that with just a wrench.

 

I used one of <these> on a water pump a few years ago, which worked very well in that particular situation. Perhaps you can try to figure out if one of these tools might be a fit for this one as well.