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Injector pump return Blockage.


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I have noticed over the last couple of weeks the old girl is blowing Shiploads of smoke, particularly under any throttle setting over cruise. My son commented on it yesterday and I followed him in the other POS. When he gave it some I realised I have the perfect bank robbery getaway vehicle. It may not be fast but it has it's own built in smoke/ invisibility screen.

I have also come to suspect the fuel return line is blocked going by the increased difficulty in bleeding the air out after filter changes when seems to require cracking the banjo bolt. The thing has also been leaking from the cap in the centre rear of the IP but I think that is just the hardening of the seal. The wifes car was doing the same and stopped completely when I tightened the nut. It's a lot easier to get to on her car than mine.

Soooo, What I'm wondering is, would a blocked return line cause a shift in the fuelling of the IP and be a possible candidate for the cause of the smoking I'm seeing?

The thing has been using heaps of fuel of late but I have no idea if this is because of the smoke, the fuel dripping out of the IP or the insane hour of gridlock traffic I have had to endure twice a day for the last fortnight.

Maybe it's a combo of all 3.p;;

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Blocked fuel return line, how?

Unless it is kinked somewhere in the chassis perhaps. Easy to test, disconnect than run the engine to see where it smokes, I personally have never seen the return line blocked in all my years working on trucks, perhaps Nissan is special.

I believe you run the old girl on bio Diesel/veg oil which could be contributing to premature wear of the pump, injectors.

You need to start with basic.

Check actual fuel pressure, confirm the return line is not blocked by disconnecting it at convenient place and see if any fuel comes out or use compressed air to blow through.

Is yours the so called inline IP?


Edited by Rumcajs
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Not sure how it would block but I haven't touched it and it's old. It could also have an accumulation of diesel scum released by the veg.

I don't believe the veg would cause premature wear. It's off the scale in lubricity compared to diesel so should cause no wear by comparison.

My pump is a rotary.

I'll try the compressed air but getting the compressor from it's location to the vehicle is a bit of a job so I just thought I'd ask if this were even possible before I mucked around trying it.

As you haven't seen this before, it's obviously not common. I could well be on the wrong track but I just thought I'd ask before getting into it and to see if anyone has had similar symptoms and found an unexpected cause. I'm not sure of the age/ mileage of the injectors but as this has come on fairly quickly and I haven't touched the fuelling in over a year, I wouldn't think it would be the injector wear unless that comes on quicker than my lack of knowledge would have me expect.

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