D40 Navara fuel injection pump issues

[4BYFOR]

https://vimeo.com/120119997
This is what it sounds like idling, the code coming up is P0093

 

[camo.b]

Is that code only coming up at idle? Im getting P0089 only on cold start and only at idle...

 

[Sean]

I am getting the p0093 code randomly and have had it for the last year or so. I have replaced fuel filters and the SCV.
Have just replaced the fuel rail pressure sensor today so will see how that goes. Its a real PITA of a problem and also dangerous at times.
My patience is wearing very thin with this car

 

[Old.Tony]

P0093 is a fuel leak ... it checks the voltage sent to the pump and compares it with the voltage coming from the pressure sensor. The listed causes in the manual are:

* Fuel pump
* Fuel rail
* Fuel pipe
* Fuel rail pressure relief valve
* Air mixed with fuel
* Lack of fuel

I'll add these possibilities:

* poor/intermittent connection on the FRPS
* poor/intermittent connection on the fuel pump
* poor earth connections (battery, engine, ecu)

Now, let's look at these individually:

Fuel pump
I don't think so especially if you're getting decent delivery of fuel and other causes have been tried and discounted. While the manual lists this item first, I'd check it last since it's the most expensive.

Fuel rail
Again, an expensive item, but easy to check - look for diesel leaks. No leaks means the rail is fine. Don't forget to check your sump oil level in case diesel fuel is leaking into there past the injector seals.

Fuel pipe
Same as rail. Visual inspection needed.

Fuel rail pressure relief valve
While the valve isn't a common failure point it doesn't mean that it can't fail. It might have a small amount of debris on it (try Liqui-Moly injector cleaner first).

Air mixed with fuel
Alway a possibility, but usually you'll have difficulty starting the car in the mornings because the fuel runs back to the tank. The best way to test this is to add a clear section of hose to the output of the fuel filter and look for bubbles.

Lack of fuel
I absolutely point-blank refuse to explain this one, even in Cantonese.

Poor/intermittent connection on the FRPS
The fuel rail pressure sensor has an electrical connection which can suffer like any other. It's really quite easy to unplug and replug this a few times to clean up the contact faces. Doing this doesn't guarantee a working FRPS, but does remove the connection as a possible cause and may even fix it.

Poor/intermittent connection on the fuel pump
Same deal here - electrical connections/gremlins are painful to track and check. They're often caused by pressure-washing your engine bay - so the simple advice is don't! Unplug the pump, replug it.

Poor earth connections
These often cause trouble. Start with the battery, removing both terminals and cleaning them, ensuring a good connection. Check the earth strap to the engine, and check near the ECU for its earth point which sometimes hasn't had enough paint removed.

 

[camo.b]

I am getting the p0093 code randomly and have had it for the last year or so. I have replaced fuel filters and the SCV.
Have just replaced the fuel rail pressure sensor today so will see how that goes. Its a real PITA of a problem and also dangerous at times.
My patience is wearing very thin with this car

Were the contacts on the frps clean?

 

[Sean]

Your a wealth of info Tony.

Camo b
Yeah have checked FRPS connections and all are clean.
Just had a thoughty. On a trip to Sydney last weekend where it went into limp mode 6 times on the way home to Newcastle, I remember one of them happened when I hit a decent sized pothole so maybe the earth connections should be the next thing I dive into.
Sorry for hijacking the thread.

 

[4BYFOR]

Ok guys it's sorted, for the last 5 years it was getting worse and worse.. It ended up being a broken wire on the fuel pressure sensor on the rail which you could not see cause of the insulation. I took it to diesel Australia and Guy got one of the boys to test it out and see what it could be.. While we were testing it the mechanic was fiddling witht the wires while the engine was running and what do you know it was idling just like it did in the mornings up and down really rough! So we got access to the wires and he pulled on each one from the plug back and got to the 3rd wire on the plug and snap the plastic broke and the wire inside was broken.. New piece of wire and soldered up heat shrink plugged it back in and what do you know... Purrs like a kitten haven't had any issues now! So thanks to these boys it's sorted and after years of limp mode it's gone!! So checking wiring like you guys stated is correct cause every time that wire lost connection the Ecu reads loss of rail pressure and limp.. The day before that it went into limp 20 times and I almost drove it into a wall.

 

[4BYFOR]

To date I have changed, rail, injectors, scv, maf and filters a few times! At least I have lots of spares lol

 

[Old.Tony]

I hate those. I visited someone down near the Central Coast one day to help them with their D21, and when I examined the wires coming off the battery it looked like someone at some point had changed the heavy wiring for engine control (there was another heavy wire for lights and that circuit worked) with single core wire - maybe Nissan made it that way. At any rate, single core is crap for mobile installations, and this one had flexed itself enough so that it had broken inside the insulator too. I temporarily repaired it for him and got his car going, but it wasn't easy to spot.

So it WAS an "intermittent connection on the FRPS" but damn, it should have just been a connector!

Can you tell me if the FRPS wire is multistrand or not?

 

[4BYFOR]

It's 3 wires Tony running into 1 insulated 3 core back to the ecu.. It really was by chance that we did find it when we were testing the rail pressure sensor