90 series D4d common rail low fuel pressure

[slightlyriskyneil]

Hi all - my problem seems to be one of a common theme: I have a 90 series D4d common rail type engine which has been putting me in crawl mode and when tested the guy says the fault was low fuel pressure (no fuel pump in tank). With some effort and trickery I can get it started and she idles fine and revs up for a while but soon the light comes back on and starting is difficult once again. I have eliminated there being any air leaks right up to the fuel pump (changed filter as well). The SCV's at (27 degrees Celsius) gave a reading of 2.4 with no variance between the two so I'm assuming they're fine. I can't believe there's a problem with the injectors as she runs so well (when running) and I am lead to believe that if the pump had failed swarfe would have buggered the injectors in any case. I'm hopefully leaning towards a misreading fuel pressure sensor (no fail as this would have shown on the diagnostic) or a faulty pressure relief valve.

Any suggestions ?

p.s. I'm poor ....................

 

[StarCruiser]

Hi Neil, you say 'you're assuming' the suction control valves are fine. This suggests it is a Denso pump as you mention the plural.

I recently visited S&S Diesels north of Southampton and while I was there had my Mitsubishi Space Star checked over after a good chat with the engineer there. Before o brought the car in I spoke to him about it and he mentioned that suction control valves often go faulty causing low fuel pressure, and they regularly change them. He thought the engine would have a Denso pump. When he found it to be a Bosch system he said their SCVs just don't give trouble.

My advice would be to be absolutely 100% certain sure that your pair of SCVs are fault free before looking for something else (I don't know what 2.4 means- ?? 2.4 what?) if the pump has failed, which it sounds like it hasn't, then you would be looking at north of a £2500 bill as that is the cost of changing the entire fuel system including tank on a Ford. Who knows what that would be on a Landcruiser so we don't even want to go there. Injectors can leak by, however that in itself I'm told doesn't cause your problem. If you take the return pipe off the pressure relief valve (and blank where it came from) and run some clear screen wash tubing from it into a jar, you should see diesel leaking by and up the tube if it's faulty. So then it's sensor or SCVs. Why would the sensor misread? Is there any corrosion on the connector?

Not sure other than that but PCVs are the first stop for a diesel shop.

Hope this helps.

Richard

 

[Shayne]

There is a filter in the tank .

 

[slightlyriskyneil]

Thanks Richard the 2.4 is a resistance test reading and it says the readings should be a bit lower at 20 degrees so I'm assuming the hight reading is because it was warmer ?? I will clean the sensor connections with contact cleaner although they did look fine ... all this started (maybe co-incidentally) when I went over some rough potholes so from the outset I have been thinking a loose connector but I haven't found the culprit yet if there is one!! I shall google the pressure relief valve test a bit further as I'm unfamiliar with their workings. The likelihood is that the pressure sensor is fine but the relief valve is operating too early bring down the fuel pressure .. I sit there on tick over all is running sweet and then I put it in gear and the pesky light comes on .....

 

[StarCruiser]

Neil, the resistance may be fine, the mechanics of the valve are not checked by this method. The valves themselves are not serviceable.

Note, if you open the fuel system, keep all possible contaminants out.

 

[Shayne]

I recently got a 1kd 90 series and did some reading at the time expecting at least some gremlins but so far so good . I could be wrong but i vaguely recall something about poor injector seals , worth a google search maybe .

I have also got a 1kz 90 and the pickup in the fuel tank has been the cause of a number of 90 series fueling problems , as far as i can tell both trucks are identical apart from the engine . You have to remove the tank to get to the filter .

 

[slightlyriskyneil]

Thanks Guys .. will feed back as and when things develop

 

[slightlyriskyneil]

During the course of my fiddling today I took out the SCV's to retest and check for other signs/symptoms ... all looked well however I put a magnet into the SCV openings on the fuel pump and from both obtained small amounts of metal swarf ... I am concluding that it is indeed the pump that has failed and perhaps in time, I am told, the Injectors will follow suit. What to do now ? I can't afford to throw a new pump at the motor at a cost of £1500 so I'm thinking of gambling on a second hand pump. The hazards being a) there is no guarantee it will be faulty as well b) I have to source the right one ..... what to do ?????

On another note: I swapped and replaced fuel lines left right and centre to eliminate the possibility of my low fuel pressure being caused by air in the system. Today it dawned on me to replace the fuel return pipe from the pump with a clear, well sealed bit of 6mm tube and when I ran the engine after a few bubbles had cleared (caused by some earlier work) the tube ran clear with only the occasional tiny bubble every now and then as a result of I don't know. I think if there had been a significant air leak into the system from the lines, pick up, filer etc it would have shown in the return saving me a lot of work on the first day !!

 

[StarCruiser]

Neil, have a look on Amayama website. Genuine Toyota parts sent from Japan and a rough price straight away. If I were you, I would change your high pressure pipes, and anything prior to the injectors. Really the swarf is so fine that it will get to the injectors and the only way to guarantee they are clean is to replace them. You could talk to someone like S&S diesels, they charge £20 each to test them. They may know if you are likely to be lucky or if you can clean them or if your only hope is to replace. If this hasn't been happening for long, you may get away with not changing the fuel tank by diverting your return pipe to a catch can, but really, how do you know you're not going to just mess up the new or second hand pump you fit. Sorry, but the only way to be sure you don't waste your hard earned and not plentiful cash is to change the lot. There's all sorts of things you can try to do but it only takes one tiny bit of that swarf and you're back to square 1. The fuel filter is not fine enough to pull out the finer stuff so you can only say that will do MOST of it.

So sorry to hear this and to pass on this info but it is in the hope that you won't go throwing good money after bad. Cheapest way is to do it right and do it once. Where are you located BTW?

 

[slightlyriskyneil]

Thanks will certainly give this some consideration as it would be unwise to just do half a job ... I'm Barking East London

 

[StarCruiser]

I guess you need an identical engine with a con rod out the side at 30k, pooing rocking horse being bitten by a chicken I reckon, but then miracles do happen. Might be worth a search for parts. If you take your injectors out, mark where they go as they are given a calibration value which is usually marked on them and is programmed into the ECU.

I thought this stuff was confined mostly to Fords at 70k or so.

If you do try S&S, they are Denso agents but I expect you could find someone recommended a bit closer to home if need be. Just be scrupulously clean room clean with any connections opened up and cover or plug up holes immediately. Do try someone that knows more about these things than the 0.5% I do. Diesel specialists are working with stuff like this all day. If you find one like S&S, then you'll get good advice.

Good luck with it Neil.

 

[slightlyriskyneil]

I've managed to source a pump second hand £250 with 6 months warranty ... think I'll have shot at it and see how things go. I presume as this is a type of constant velocity pump that it doesn't need to be timed on the belt drive ?