P38A [RESOLVED!] P38 DSE non start - fuel issue

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
P38_OTMS said:
Glow plugs were bench tested and all six work just fine. Perhaps something electrical between the relay and the plugs but the plugs themselves are all fine.

I have just thought though... the wiring on the hot start is a bit dodgy and the temp sensor wire is loose - probably got something to do with it...
Click to expand...

Last time you tried to find sensor you pointed to number for injector plug. The ECU temp sensor is green in colour and screwed into the head between inlets 3 and 4. That is the sensor that tells the ECU engine temp for start fuelling and glow control. If it is faulty the ECU uses a preset of 50 degrees. That is why i told you to leave the hot start disconnected until you had sorted all problems.
 
wammers said:
Last time you tried to find sensor you pointed to number for injector plug. The ECU temp sensor is green in colour and screwed into the head between inlets 3 and 4. That is the sensor that tells the ECU engine temp for start fuelling and glow control. If it is faulty the ECU uses a preset of 50 degrees. That is why i told you to leave the hot start disconnected until you had sorted all problems.
Click to expand...

Yea we replaced the temp sensor with another one, as part of the process of elimination. Funnily enough the replacement sensor didn't work and showed up on diag that it was faulty. We replaced it with the old sensor and that issue went away. For peace of mind I'll order a new sensor but pretty sure thats a red herring. Don't want to undermine your fountain of knowledge but I'll rewire the hot fix properly later and see what happens.
 
P38_OTMS said:
Yea we replaced the temp sensor with another one, as part of the process of elimination. Funnily enough the replacement sensor didn't work and showed up on diag that it was faulty. We replaced it with the old sensor and that issue went away. For peace of mind I'll order a new sensor but pretty sure thats a red herring. Don't want to undermine your fountain of knowledge but I'll rewire the hot fix properly later and see what happens.
Click to expand...

Diagnosing problems is far easier if the car is returned to standard first. Disconnect tuning boxes, Hot fix Etc first before starting out. Many use things like that to mask a problem rather than cure a problem. Then the problem just gets worse behind the shield.
 
Last edited:
wammers said:
Diagnosing problems is far easier if the car is returned to standard first. Disconnect tuning boxes, Hot fix Etc first before starting out. Many use things like that to mask a problem rather than cure a problem. Then the problem just gets worse behind the shield.
Click to expand...
As said, they tend to just mask problems.
 
Think I've got to the bottom of it. Leak off pipe between injectors 2 & 3 is damp and there's a fair bit of fuel down there. Just ordered some pipe so will see what happens.
 
Hi, reviving this post as I have the same initial problem, leaved the car overnight, in the morning no lighst in the dash regarding glow plogs, nu feed on the glow plugs relay, no feed on the injection pump cutoff. All the above are working but not getting feed.

P38_ OTMS user said
" Update time: after managing to fix the rovacom we couldn’t talk to the Ecu. Finally found that the engine cut out fuse was broke"

and all above were fixed

Can anyone point me in the direction of the location of "engine cut out fuse" ?

Hope someone will answer :)
 
Razvan said:
Hi, reviving this post as I have the same initial problem, leaved the car overnight, in the morning no lighst in the dash regarding glow plogs, nu feed on the glow plugs relay, no feed on the injection pump cutoff. All the above are working but not getting feed.

P38_ OTMS user said
" Update time: after managing to fix the rovacom we couldn’t talk to the Ecu. Finally found that the engine cut out fuse was broke"

and all above were fixed

Can anyone point me in the direction of the location of "engine cut out fuse" ?

Hope someone will answer :)
Click to expand...
Have you checked the fuses in the under bonnet fuse box?
 
Yes, after I posted I also disassembled the fuel cutoff switch and put it back together. So no feed to the fuel lift pump, no feed to the plugs relay and no feed to the pump shut off valve. Gave 12v to the shutoff valve and started the engine on first crank but wierd that it got on 5000rpm an stayed there. I fast remove the jumper cable and engine stopped. After that I proceedet to the fuse box reconditioning. It had some water damage, resoldered everything in it, smelled like burnt but no brown signs on it...Will post tomorrow after I mount it in the engine bay. I also have a lot of spare relay from my other p38's in case this does not do it. If no succes then I really don't know what to do, guess I'll have to eat some repair manual to understand hou those three gringos are powered.
[GALLERY=]
16613761515662158831860264949205.jpg
[/GALLERY]
 
Razvan said:
Yes, after I posted I also disassembled the fuel cutoff switch and put it back together. So no feed to the fuel lift pump, no feed to the plugs relay and no feed to the pump shut off valve. Gave 12v to the shutoff valve and started the engine on first crank but wierd that it got on 5000rpm an stayed there. I fast remove the jumper cable and engine stopped. After that I proceedet to the fuse box reconditioning. It had some water damage, resoldered everything in it, smelled like burnt but no brown signs on it...Will post tomorrow after I mount it in the engine bay. I also have a lot of spare relay from my other p38's in case this does not do it. If no succes then I really don't know what to do, guess I'll have to eat some repair manual to understand hou those three gringos are powered.
[GALLERY=]View attachment 272230 [/GALLERY]
Click to expand...
If the box smelt burnt, you will need to check the connectors as they go slack with heat and fail to make good contact.
 
So, I mounted the fuse box, and I am in the same situation. Decapsulated relay for main engine Rl19 and relay for ignition coils/maf/etc RL15 and manually activated them and I can hear the ABS pump, plugs relay and injection cutoff valve working. So conclusion is that I have no comand to these relays when ignition is on.
Does anyone know from where the command is made for activating the relays?


Datatek said:
If the box smelt burnt, you will need to check the connectors as they go slack with heat and fail to make good contact.
Click to expand...

Thanks for reply
I have just reconditioned the fuse box
 
Best start a new thread starting from scratch with your symptoms. I'm a bit lost on where thsi starts.

The car will not run if the engine management system (securiry) code does not match the code stored in the BECM. If the car is mysteriously immobilised that would be my guess, especially if it has had low volts from RF interference draining the battery.
 
Razvan said:
So, I mounted the fuse box, and I am in the same situation. Decapsulated relay for main engine Rl19 and relay for ignition coils/maf/etc RL15 and manually activated them and I can hear the ABS pump, plugs relay and injection cutoff valve working. So conclusion is that I have no comand to these relays when ignition is on.
Does anyone know from where the command is made for activating the relays?




Thanks for reply
I have just reconditioned the fuse box
Click to expand...
I do understand you have reconditioned the fuse box, but the spade connector receptacles become slack over time and with heat.
I think you have an immobiliser problem.
 
Grrrrrr, thanks for the reply.

Found some information on some other related forum that pin 9 from c120 white wire from becm should supply pin 8 from C173 purple connector under fuse box. I think this should power my relays.
the wire has almost 12 v probably from the relay coil in the fusebox. When I switch key to ignition 2 this wire shoud receive from the bcm negative or ground. But it does not.
I do not think it is an imobilisation problem as I have Abs and eas errors in the dash when ignition in position 2. If it was imo the errors should not be there. I now suspect the becm.
I will cut the wire and feed it ground to see if car runs.
Any other ideas are welcome, in thw meantime this turns into another problem that I should write somewhere elese
 
Last edited:
Car fixed... by god probably...
So I cut the white wire pin 9 c120 from becm, no ignition 12v, ignition position1 12 v, ignition position2 12 v. I fed the rest of the wire that goes to the fusebox wit ground and started her up. Runs like a charm, and I say that because engine is new, 1600km, :D , than measured wire from becm pin 9, now it was ground. Whaaaaaat? And in one of my many dumb moments I said that I shoud connect it while engine running with the wire that goes to the fusebox, that was still connected to ground by me. Did that, than I removed the jumper to ground that I made so the conections now are as they were initially. Than stopped the engine, and started it like 30 times to be sure because I could not belive that is cured.
Will see in the morning if she still behaves :).
Did a lot of things to fix this but in the end I actually did nothing. Maybe discovered a way to start your p38 when it is immobilised.
I suspect a transistor or something in the becm that tripped.
Thanks everyone for your involvement and especially god :). Please fix all other issues with my p38 in the same manner :)
 
Razvan said:
Car fixed... by god probably...
So I cut the white wire pin 9 c120 from becm, no ignition 12v, ignition position1 12 v, ignition position2 12 v. I fed the rest of the wire that goes to the fusebox wit ground and started her up. Runs like a charm, and I say that because engine is new, 1600km, :D , than measured wire from becm pin 9, now it was ground. Whaaaaaat? And in one of my many dumb moments I said that I shoud connect it while engine running with the wire that goes to the fusebox, that was still connected to ground by me. Did that, than I removed the jumper to ground that I made so the conections now are as they were initially. Than stopped the engine, and started it like 30 times to be sure because I could not belive that is cured.
Will see in the morning if she still behaves :).
Did a lot of things to fix this but in the end I actually did nothing. Maybe discovered a way to start your p38 when it is immobilised.
I suspect a transistor or something in the becm that tripped.
Thanks everyone for your involvement and especially god :). Please fix all other issues with my p38 in the same manner :)
Click to expand...
Transistors do not "trip" they work or fail. I suspect there is a bad earth connection.
 
You must log in or register to reply here.

Similar threads

L
Sport Glow plug light
Replies
6
Views
399
lj5000
L
P
2008 L322 4.4 Cranks but No Start
Replies
2
Views
694
Wazzajnr
Wazzajnr
jimmacD
Back to the P38 house of pain!
2
Replies
21
Views
1K
Grrrrrr
Grrrrrr
jimmacD
P38 2.5 FIP fuel flow.
2
Replies
25
Views
919
Datatek
Datatek
G
P38 1995 Diesel in tank pump plug wire identification
Replies
7
Views
510
RangeRoller dt
RangeRoller dt
Back
Top