P38 Diesel starting problems

I am having intermitant problems with starting ... but only in the last week.

Suddenly I am finding it very difficult to start the vehicle. It can take 4-5 attempts for 30 seconds to get it going. Sometimes it starts first time(this can be cold or warm)

When attempting to start, the motor turns over OK but there is nothing happening. Once started, the vehicle runs fine. I am guessing that there is no fuel system problem because of this but am I right?

Not sure where to start.

Any advice would be greatly recieved.

Many thanks

Stuart
2.5DT Range Rover

Hi

Could be the temp sensor on the engine is duff fooling the ECU into thinking it is warm enough to switch off the heater plugs.

I hope this helps

Cheers

Adam

Thanks Adam.

You will have to bear with me as I am a bit of a novice. Which temperature sensor do you mean? Engine coolant, fuel temp, air intake?

Stuart

Start with the obvious first: have you changed the glowplugs? The starting performance doesn't necessarily deteriorate over time but can happen in the space of a couple of days.

Next is the problem happening with less than one-third full tank? If so you're in-tank pump has stopped working.

I have not changed the glow plugs.

In terms of the in tank fuel pump - would this not mean the engine would not run at all? Once I get it to start it works fine.

Sounds like it is something to do with glow plugs or a sensor as advised.

Change the plugs first then, they don't last all that long so worth doing.

You'd think that would be the case, but the injector pump can suck diesel from the tank when it is above one-third full even without the in-tank pump running, but below that it will have trouble starting and eventually will cut out when running.

If the fault is that intermittent, can you get your hands on a test light. When the motor will not start put your test lamp between an earth and the connection on the end of a glow plug. It may be the 12 volt supply from the glow plug control unit failing. If your test lamp lights up when it’s not starting then suspect the glow plugs. If it doesn’t then suspect the glow plug control unit.

Sorry I forgot to say, the test must be done cold unless you pull the coolant temp connector off which forces the glow plug control to think it’s very cold. Going with what Adamrharding said it could well be the coolant temp sensor.
Also check or replace the vacuum pipe that goes from the inlet manifold to the Manifold air pressure switch on the passenger inner wing. Also check or replace the Injector leak off pipes for any signs of damp from fuel leakage. The one going to the pump is a favourite for perishing. Both the leak off and the map switch pipes are braided and either leak or suck in air causing the same fault. They are difficult to check without a vacuum gauge so i would just replace them if they look a bit tatty. Its cheap enough for 1 meter of pipe

Thanks for all the advice. Upon closer inspection this morning I found there is air in the fuel pipe after the fuel filter. Also, my tank is less than 1/3 full.

I will take a look at the suggested remedies over the next few days.

Thanks

Stuart Parker

Stuart,
Had the same problem with mine.
Fixed with a £5.00 one way valve in the fuel line between filter and block..
Hope this helps,
James.

Mine started playing up a few weeks back. I changed the leak-off pipes between the injectors, but that didn't help (the old ones were about to split anyway, so worth doing).
Decided it must be the glowplugs as it would start OK if only left for a few hours. Took it to my local specialist who tested them for me and found that 3 weren't working.
6 new glowplugs at £9 each and £45 to fit them and now it starts on the button

Friend of mine had this problem he just poured cold water on his temperature sensor and it started fine.

james2.5dse said:

Stuart,
Had the same problem with mine.
Fixed with a £5.00 one way valve in the fuel line between filter and block..
Hope this helps,
James.

Click to expand...

Cured my problem as well, plus i changed leak of pipes

ive heard that the bmw lump has a common problem with fuel leaking back into the tank via the feed pipe, fit a 1 way valve and should cure it, if not its prob the glow plugs, the the hot start problem which they are common for

hi mate check out the pick up pipe and sender unit in the tank mine sucks in air at a quater of a tank of fuel over that its ok this is a common problem with these p38 dts its worth a shoot keep an eye on your fuel gauge when it does it .

Does the change in starting match with the colder weather? If it does suspect the glowplugs, as you can get away with a drop-off in their performance whilst air temps are warmer but your buggered once there's a chill. Used to have similar problem with old Mondeo, which did fine all summer but seemed to need new plugs every couple of autumns.

When you say between the filter & the block do you mean the fuel pipe leading from the filter to the fuel pump? or?
..and obviously 'out' on the valve means fit out to the fuel pump?

thx
oldskoolpro


'Had the same problem with mine.
Fixed with a £5.00 one way valve in the fuel line between filter and block..
Hope this helps'

Where did you get the valve from? Any body got a link to one they bought?

Also best place to put it.

Mine is only starting if I leave it on a slope facing down hill at the moment.