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Gribble *******
Joined: 11 Oct 2007 Posts: 8448 Location: Holset H221W
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Posted: Thu Mar 13, 2014 10:52 Post subject: |
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Nearly right , the back of the head has a restriction in the banjo bolt where the fuel comes out which keeps a pressure in the gallery round the injectors.
So the primer will go hard when the fuels under pressure as its only a small piston in it . If you take the return pipe off fuel will run and when it stops the the primer should be easy again .
The fuel flows all the time so its not really excess going to the tank its like the Cummings engine PT system (pressure time ) and does get up to 60C or more when the engines working hard .
Only one of the bolts where the fuel temp sensor is the banjo and only one hole is the fuel outlet .
Also the sleeves only sit with the holes in line with the fuel gallery .
But I'm sure you did this .
If you cant suck up diesel from the tank or blow down the return line easy thats where the problem is .
Also the hand primer has a check valve in it ,this does two things its keeps the fuel in the line from the tank and provides a 'head ' (positive inlet pressure ) to the mechanical lift pump which is a positive displacement type pump i.e. it wont suck as such and needs fuel in it to pump .Once its got the fuel its fine but any gap in the lines and its no fuel time .
You could fit one of those in line electric pumps bout 30 quid off the bay which gets rid of all this in one go ,I do on small plant which has fuel troubles and the older style PowerScreen Powergrids as the were pure baassttards with that belt driven lift pump on the Deutz !
So heres how I see it ; you pump up from the tank with the squeezer alls ok , take that off and wooosh the fuels down the line and back to the tank so no start . _________________ 2 New Troopers ! |
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Posted: Thu Mar 13, 2014 10:52 Post subject: Google Ads keep this community free to join! |
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eithan h Moderator
Joined: 11 Dec 2005 Posts: 8195 Location: oxfordish
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Posted: Thu Mar 13, 2014 12:00 Post subject: |
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Yes it will go hard so that's ok but some people do get the banjo bolt in the wrong he when they bolt the unit to the back of the head, did you notice one bolt was different? |
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Jasetheace *
Joined: 05 Sep 2012 Posts: 28 Location: Margate
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Posted: Thu Mar 13, 2014 20:01 Post subject: |
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Hi guys, I did the head about 6 thousand miles ago and its been fine. The problems seem to have started after changing the tank.
Ive pumped the fuel from the tank using a hand primer missing out the fuel filter housing because the hand primer on the car has never worked and the car still wont run.
Ive taken the pipes apart and they still have fuel in them and it hasn't dropped back to the tank.
Will it not pull the fuel direct from the tank if the filter housing is not connected, will it not create the same pressure?
Has any one had any problems with the after market tanks? Although I cant imagine what problems it would have to stop the engine working?? |
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eithan h Moderator
Joined: 11 Dec 2005 Posts: 8195 Location: oxfordish
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Posted: Thu Mar 13, 2014 20:04 Post subject: |
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yes you can put the pipes straight to the fuel pump and it would run fine |
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Jasetheace *
Joined: 05 Sep 2012 Posts: 28 Location: Margate
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Posted: Sat Mar 15, 2014 15:21 Post subject: |
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So, Ive taken retrun pipe off and pumped it up, I get a drip. Bulb goes rock hard and I get drip....drip....drip, should it run out in a steady stream?
I'm going to get someone to turn it over while I watch and see if it changes on cranking. I wonder if the lift pump has gone? |
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eithan h Moderator
Joined: 11 Dec 2005 Posts: 8195 Location: oxfordish
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Posted: Sat Mar 15, 2014 17:23 Post subject: |
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It would be rare but you can take that part to bits and swap it over from another vehicle, are you sure your getting enough oil pressure to fire the injectors? |
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Jasetheace *
Joined: 05 Sep 2012 Posts: 28 Location: Margate
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Posted: Sat Mar 15, 2014 18:01 Post subject: |
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I suppose it could be oil pressure, is there an easy way to check? When crancking is does cough every now and then as if one injector has fired. There is also the odd puff of smoke where it has fired.
I whacked an extra couple fo litres in but it has not made any difference?
jase |
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Browndoff *****
Joined: 22 Mar 2013 Posts: 513 Location: Dublin 13, Ireland
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Posted: Sun Mar 16, 2014 16:31 Post subject: |
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"I've taken return-pipe off and pumped it up - I get a drip" THAT doesn't sound right at all! As mentioned by Mr G:- " if you can't blow to the tank - the line is blocked!"
I'd start by removing the Banjo-Bolt at the exit-point - to see if the blockage is within THAT. With it OFF, I'd try again to Pump fuel through the Head. If it still won't come out 'strongly', then it's possible the internal galleries have been blocked with rust and dirt from the fuel. Try again, with an air-line connected at the point where the fuel-line runs INTO the Head [by-passing Filter and Pump]. If you can't get a flow from end to end of the Head itself - I'm afraid you're in trouble!
If you DO get a good flow at some point - then the blockage lies in the last section which you have disconnected from the fuel-supply-system - so strip it down and hunt for the culprit! _________________ 2002 LWB Trooper 3.0L
I've done some major repairs, including replacing half-shaft, replacing fuel-injectors etc. |
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eithan h Moderator
Joined: 11 Dec 2005 Posts: 8195 Location: oxfordish
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Posted: Sun Mar 16, 2014 18:54 Post subject: |
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put an airline on the fuel inlet to the head and you will blow the injector seals |
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Jasetheace *
Joined: 05 Sep 2012 Posts: 28 Location: Margate
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Posted: Mon Mar 17, 2014 21:11 Post subject: |
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So, quick update, Got lots of oil pressure into injector rail.
I have also got fuel through the head and out the back and it flows through on cranking so that's all good.
Now on cranking it tries to fire so Im thinking its the oil pressure in the rail and I have read on here before about the oil pressure regulating thingy.
There are 2 So which one is which? and what does each do? I have read that after changing they need setting up on the Isuzu diag tool is this correct?
Trouble is my Isuzu dealer is miles away and itll cost me more than its worth to get it there?? Do they do home visits!!
Jase |
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Browndoff *****
Joined: 22 Mar 2013 Posts: 513 Location: Dublin 13, Ireland
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Posted: Mon Mar 17, 2014 21:28 Post subject: |
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Just some basics, Jase............
In the 4JX1, the High-Pressure Oil-Pump creates the high-pressure oil [so the TYPE of oil is crucial - it must be 5W-30 fully synthetic], and this is metered down to the 'ideal' pressure by the Rail-Oil Pressure-Control Valve - and cross-checked by the Oil-Rail Pressure-Sensor. At a signal from the Engine Control Module, the Injector-Solenoids allow-in some of this HP-oil into its internal hydraulic pump and it forces a jet of ultra-high-pressure Diesel into the cylinder. It fires and runs happily and speeds up if the oil-pressure is allowed to increase and slows down when it's reduced by the action of the ROPCV - under the command of the ECM.
The 4JX1 Engine won't start if the Oil-Rail Pressure-Sensor tells the Engine Control Module that there's NOT ENOUGH oil-pressure [high voltage signal] - which could be 'cos the ORPS is FAULTY - or because the pressure REALLY is too low. If it IS too low - it's usually 'cos the Rail-Oil Pressure-Control Valve is stuck open and draining all the HP-oil back into the Pump's reservoir. If the oil-pressure is OK [but it still won't start] - then it's not getting the fuel - 'cos the filter is blocked - or some other SIMPLE fuel-line problem.
Now, we've been working on the impression that you had a fuel-line problem - no flow of fuel through the Head. Is that now fixed? "It flows through on cranking" I thought you said it goes "Drip, drip, drip....."! What have you done that has fixed it? If the fuel problem IS fixed - it OUGHT to start! The occasional 'bang' and puff of smoke means that it's getting enough pressure to fire the injectors - but probably NOT ENOUGH FUEL to keep the engine going.
There's no point in messing with the ORPS or the ROPCV if the FUEL PROBLEM is NOT yet fixed - and probably no NEED to mess with them if it IS FIXED!! BTW - only the ORPS needs to be zeroed at the ECM with a Tech2 - but it's unlikely to be faulty if it's allowing even 'occasional' firing! _________________ 2002 LWB Trooper 3.0L
I've done some major repairs, including replacing half-shaft, replacing fuel-injectors etc. |
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eithan h Moderator
Joined: 11 Dec 2005 Posts: 8195 Location: oxfordish
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Posted: Mon Mar 17, 2014 21:37 Post subject: |
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you can remove and clean the orcv and there is a very sticky somewhere done by mr G on how to do it, the orps can be bypassed by removing the white (or dirty yellow/brown by now) wire in the big plug by the dipstick. after this your probably going to need a tech2 to see what the oil pressure is actually doing, you could have flow but no pressure which could indicate a knackered hpop or it could be a poppet valve in an injector leaking or an injector seal where it bolts to the gallery |
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Jasetheace *
Joined: 05 Sep 2012 Posts: 28 Location: Margate
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Posted: Mon Mar 17, 2014 22:38 Post subject: |
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So, to answer your questions Browndoff, I took the Banjo bolt out the back of the head, I pumped fuel through and it flows freely to that point. There was no dirt or restriction in the banjo bolt. I blew out the retun with the bolt out and then put the bolt back in. Fuel flows out of the return until the gallery is full then pressure builds and the flow slows to a drip however on cranking fuel flows. I think I may have been barking up the wrongtree with the fuel from the tank thing. I now think it lays with the injectors or oil to them.
If the injector rail is gtting some pressure would that not be enough to fire and odd injector? |
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eithan h Moderator
Joined: 11 Dec 2005 Posts: 8195 Location: oxfordish
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Posted: Mon Mar 17, 2014 23:40 Post subject: |
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Not really as the ecu won't enable the injectors until it sees the correct pressure when the hpop goes you get about 1.6 mpa of pressure but the engine needs to see 3-4 mpa to start then about 4.6 ish to run when cold. |
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Jasetheace *
Joined: 05 Sep 2012 Posts: 28 Location: Margate
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Posted: Tue Mar 18, 2014 11:01 Post subject: |
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So would any of my symptoms be caused by any of the valves or switchs on the injector rail? it now fires on more than one cylinder but wont run |
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