Another CX5 problem. My daughter and I drove to Melbourne in her CX5.die sel 2013. This car has been giving us grief since we got it. Ended up with replacement engine but still having issues. The car loses power on hills and their is no acceleration. Have been to mazda several times but issue not solved. Driving home last week and car started doing same thing, no acceleration on a hill, sort of limped to top of hill and then it comes good. We almost got home and it did it again but not really any incline. Pulled over, gave it 5 minutes and car started ok and we continued on. 200metres further up the road, same deal, had to pull over, engine light and battery light on. Gave it a rest, would not start. Turning over but no go. I thought fuel issue. Towed to Mazda dealer. Eventually looked at by them. I had suggested possible issue with high pressure fuel pump.
After 2 days Mazdas diagnosis was that the engine fuel rail pressure was NOT HIGH.?? They then said low pressure fuelines from filter were around the wrong way. This is their solution and car now running. Has been a few days but car has not been on incline yet.
My question is how can the fuel lines from the filter be on the wrong way. I replaced the filter when we had earlier issues and it was replaced the way it was taken out. Surely if the hoses were on wrong the fuel would not get through at all or at least cause issues even in normal driving??
If the fuel rail pressure was low the surely that means the high pressure fuel pump is the possible issue not the lines from the filter.
Open to some opinions please as to whether this solution as stated by Mazda is even possible. Thanks Murray

 

Cheating but My intial reaction was only if a valve was built in so I asked calude ai:

How Fuel Lines Can Be "Wrong"

Diesel fuel filters typically have an inlet and outlet side, and the direction matters:

• Correct direction: Tank → Filter → High-pressure pump → Rail → Injectors
• Reversed: If inlet/outlet lines are swapped at the filter, fuel tries to flow backward through the filter media

Why It Matches The Symptoms

This would cause EXACTLY the issues you describe:

1. Works on flat ground - At low demand, even restricted/backwards flow provides just enough fuel
2. Fails on hills - High load = high fuel demand, and the restricted supply can't keep up
3. Low fuel rail pressure - The high-pressure pump is being starved of fuel
4. Intermittent issues - Air can get sucked into the system through the incorrect connections
5. Eventually won't start - Air locks or complete fuel starvation

Why You Might Not Have Noticed

If the lines were already backwards when you replaced the filter and you "put them back the same way," you'd perpetuate the problem. Possibilities:

• Previous owner or mechanic installed them wrong
• The replacement engine installation had something crossed
• Filter housing isn't clearly marked which side is in/out

Could It Be The High-Pressure Pump?

Yes, but Mazda's fix is cheaper to try first. If swapping the lines fixed it, that WAS the problem. Give it a proper test on some hills to confirm. If it comes back, THEN suspect the high-pressure pump.

Bottom line: Their diagnosis makes technical sense. Test it thoroughly on inclines!

 

Took it for a drive today and seems ok, but after so manyprevious visits to mazda , will wait and see. What you described makes sense except i dont see how there was enough fuel for normal driving. Appreciate your input and will post if no more issues.