Hello, I'm not going to claim any massive car experience but I've been tinkering around my 2018 Nissan Xterra, which is pretty similar to your Navara, over the years. I had an almost identical issue last year. Black smoke, poor fuel economy... the works, just like yours, turned out to be a defective fuel pressure regulator. I sorted it out at my local workshop. Cost a bit though, around 250 Euro. It's worth considering. Of course, remember, this could totally vary with your vehicle specifics. Do you have any outstanding service or recalls on your Navara? Any mods done to your beast? Have you run a diagnostic scan? Sharing such info can help me point you in the right direction. Cheers!

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Hi, Thanks for the tip, a faulty fuel pressure regulator does seem like a plausible culprit given the symptoms. To answer your questions, there aren't any recalls or outstanding services per say on my Navara. In terms of modifications, nothing outlandish, just a cold air intake I installed a while back, but that's about it. I haven't run a diagnostic scan yet, been wanting to take it to my usual mechanic but he’s been booked out recently. While waiting, I thought to gather some insights. Oh and my Navara's done around 61516 KM so far, last serviced it a few months ago and was all good then. Appreciate if there's anything else that comes to mind based on my mileage and latest service. Cheers!

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Hey, Good to hear you've kept your Navara pretty stock. A cold air intake shouldn't cause this kind of drama. The mileage is decent too - not very high. Just a quick check, you've been using the recommended fuel, right? I know Navara should take premium but some folks go for regular petrol to save a few bucks, and let me tell you, that can really mess things up. So back to your problem, the fact that your Navara was running fine a few months ago during its last service is kinda head scratching. Mixture control running rich might indeed be happening, but it’s usually due to some underlying issues. This could be a leaky fuel injector, a faulty oxygen sensor, or like I mentioned before, the fuel pressure regulator. The only way to confirm is really to run that diagnostic scan. Your best bet is to get your Navara to a reputable workshop as soon as your regular mechanic is available, and run a proper diagnostic scan to understand the root cause. In the meantime, try not to push her too hard on the road, all right? Let me know how it goes. All the best!

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Hey again, Appreciate the thoughtful advice, and yes, I've been religiously using the recommended fuel. But you're right, it's a bit bizarre given she was fine just months ago. I suppose no point wracking my brains out before running a diagnostic scan. Based on what you've shared about the fuel pressure regulator and other possible issues like the leaky fuel injector and the O2 sensor, I have a good idea of what to discuss with my mechanic once he gets onto it. In the meantime, I'll take it easy on the ol' gal on the road. I'll drop an update once the diagnostic scan's done and we figure out the root cause. Till then, take care and cheers for the help!

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