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Need help to get my p38 diesel running non start.

1K views 7 replies 3 participants last post by  kapilamuni 
#1 ·
Hi all new here to the forum to see if there is any wizards out there able to shed some light. Plus it's nice to have a forum up incase people are looking for help with the Same problem.
So I bought a p38 diesel off of a mate of mine as a non runner for an absolute steal. He said he was driving it before lock down parked it up and then the battery went flat then it was a non start, so put a battery on it and tried then said to me basically the fuel wasnt getting there. So I pick it up do some investigation work realise no fuel to the filter bowl and masses of air in the pipe but the fuel wasn't that far back, so I take the pump relay out and bridge it no noise or fuel prime what so ever. Checked power with the fuse bridged and made a hole under the seat to get to the intank pump there was sufficient power at the plug, so I ordered the intank pump, fitted this first flick of the key lots of diesel. Now the guy I bought the truck off said his mate had been there and said they had various fuel lines off etc hense the air lock bled it all through and now I have fuel coming lovely out of every injector except number 4. ? 👀. The truck turns over fire runs for about 1-2 seconds and stalls every time. So out came the computer no codes present. Looked at Live data didn't show a great deal when it was turning over. Thought maybe it's a crank sensor ordered a fresh one set it right to my mark where the old one came out. Still the same. Now I am finding it very very strange how injector 4 is the one getting no fuel and has the sensor on for what I believe is start of fuel injection? A lot of the stuff I'm use to the wire on the injector is for cold start advance on idi engines. I got the eka code from the dealership no luck. Tried re-syncing the key no luck. No I know these things are stupidly sensitive but I am very mechanically minded and built several engine from scratch top to bottom so I know my way around them and I'm fairly familiar with these trucks. I'm just at a bit of a lose tbh. So if some one can answer the correct question and it's correct I'm more than happy to send the winner a couple drinks afterwards. Many thanks
Sam.
 
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#2 ·
Sounds as though you are approaching it logically. The fact that the truck fires up even though it cuts out after a few seconds proves the sync is ok I think.
i assume you are cracking the unions on each injector in turn when someone cranks it to see if fuel is coming out? No.4 injector is expensive if that is the problem. It was around £200 last time I looked.
I have got the later diesel with EGR and plastic inlet manifold so nearly all my experience is with that.
The spill back pipes on the injectors are important. Replace them all. Cheap to do and takes about an hour. It is 3.2mm tubing. Get the proper stuff from a motor factors. Also replace the manifold pressure tubing under the manifold. It perishes and can leak.
When you have done that unplug the MAF if it has one and try starting it without. The MAF affects starting, engine running, even gear changes.
The problem could be lots of other things but try these first.
 
#3 ·
Sounds as though you are approaching it logically. The fact that the truck fires up even though it cuts out after a few seconds proves the sync is ok I think.
i assume you are cracking the unions on each injector in turn when someone cranks it to see if fuel is coming out? No.4 injector is expensive if that is the problem. It was around £200 last time I looked.
I have got the later diesel with EGR and plastic inlet manifold so nearly all my experience is with that.
The spill back pipes on the injectors are important. Replace them all. Cheap to do and takes about an hour. It is 3.2mm tubing. Get the proper stuff from a motor factors. Also replace the manifold pressure tubing under the manifold. It perishes and can leak.
When you have done that unplug the MAF if it has one and try starting it without. The MAF affects starting, engine running, even gear changes.
The problem could be lots of other things but try these first.
Thanks for the reply mate. So yea I believe the sync is all I check as it really has everything to start. But something is holding it back I'm sure it's something very minor. So I changed all the leak off pipes anyway as one was split and put a new vac line on anyway as I had it all to hand. Mine is also the egr with plastic inlet type. The inlet manifold is currently removed but it should in theory still run with that off. ? I have got another injector off of another truck but I cut the wires to get it off, but a simple rewire should sort the trick out. As for the bleeding the injectors yea I do them one at a time and they all have so much diesel except for number 4. Which in turn tells me the injection pump hasn't followed through infact actually looks in really good nick. To be honest the MAF is one thing I haven't even checked power to or unplugged, I mean the air box is off but that's as far as I've got with that. So I'll try that first. I mean it's just a little bit confusing but I'm sure it's something right under my nose staring at me. I mean I am also going to check that the egr is actually moving as if it's too far closed could cause issues anyway. But it's disconnected at the moment due to the inlet being off. I've gone through all of the basics so far my bet is a sensor of some description I didn't even think off the MAF what an idiot. Will update the post shortly. Thanks.
 
#4 ·
I guess the engine should start and idle with the inlet manifold off. Don't know, I haven't tried it. Watch you don't drop anything into one of the inlets!
The manifold pressure sensor would normally be measuring zero bars gauge (or 1 bar absolute) on tickover even with the manifold on and the turbo running.
Turbo boost doesn't start to kick in until 2000 rpm. A diesel never gets vacuum by the way. It is not a vac line like a petrol car.
When the MAF is unplugged it reverts to default settings which should allow the engine to start but it will be well down on power.
 
#5 ·
Yea I'd of thought that tbh started plenty of Cara with out inlet on including a 320d BMW and there far to sensor happy. So I'll be happy with that. I'll try the maf tomorrow as that is a really good shout tbh I won't try drive it if it starts I'll buy a new one then try then.
 
#6 ·
Right so today I unplugged the MAF and messed about with a few bit until the battery went flat. So it's on charge and I've got a a second hand 4th injector to whap on I stole off of a mates truck. But I'm going to get the 27mm socket and cut a grove in it to accommodate the wire. As hes cut the plug off 🤦. Ideal. Any more suggestions as to where to go from next? I'm fairly certain it's this 4th injector as strangely no fuel to that one. The rest spray diesel like mad. Works busy but I'll update as soon as I can.
 
#7 ·
You can get a special socket for the injectors with a window in it which saves making one. Next step is to replace injector no.4 like you are already planning.
If it still won't start, check the under bonnet wiring harness carefully from the FIP all the way back to the engine ECU. Look for damage, unplug everything then give it a squirt of contact cleaner.
If you are getting diesel at all of the injectors, it must be the timing. No telling what the previous owner did. Has he had the Fuel Injection Pump off and put it back in the wrong place?
No.4 injector detects the start of the fuel injection angle but the timing is controlled by the FIP via the ECU. The ECU also gets a reading from the crankshaft position sensor.
There are various other sensors like manifold absolute pressure, fuel temp, coolant temp and throttle position sensor that feed into the ECU. I think if any of them are faulty it just reverts to default settings.
The only one I am aware of that would shut down the system is the servo unit potentiometer in the top part of the FIP. If that was the case I would expect the fuel stop solenoid in the FIP to shut off the fuel.
I am not sure about that though. You say yours has diesel at all of the injectors except no.4.
Let us know how you get on with unplugging the MAF and changing No.4 injector first.
 
#8 · (Edited)
Yes Dave, can run the car without inlet manifold. I just ran it after replacing the stop solenoid, about an hour ago.

Also, you can run the car without connecting no 4 injector. You will get the CEL.
But can't run it with crank sensor disconnected. It will start but run at about 4000 RPM , scary & prompting immediate shutdown. You are in a huury to shut it down , no time to see whether CEL came or not. :LOL:

With the OP s problem, even if the 4th injector is completely dead (electrical & fuel) , car should start with 5 cylinders but will be shaky.
Must be glow plugs (3 or more dead. but if starts will stay on) or sucking air into fuel line or fuel quantity current value too high or too low ( should be around 5 mg/str).
 
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