P38 Cutting out when Changing down

Hi All,

New to the site so I don't know if this is in the correct place if not let me know where to put it.

Anyway I have a 2000 2.5DSE P38 (BMW) and it cuts out when slowing down at junctions etc however, it only does this when the engine is hot, temp gauge points to 11 or 12. I have just replaced the in tank pump, return lines, the water pump and fixed a leaky injector. The water pump exploded and the garage spent ages pulling bits of it out before they could replace it. The problem is intermittent as i can drive 30 miles and nothing happens but if I drive a few miles around town it will cut out going around a corner. Engine always restarts first time however if i pop into the shops for 5 minutes it will take ages to restart when i come out, it is like it is not getting any diesel. Another point though I am not sure if it is related, but my mileage has gone from 32 to 22mpg and i dont know if my fan is running fast enough.

Does anyone have any idea what the problem as the local garage doesn’t?

PS. Can anyone tell me how to delete a post as I put the original in the wrong place?

welcome, have a look at hot start fix. you get them off ebay, get one with a timer on it..

Someone didnt use the search did they ? Hot start fault.

Hi rewmer,

I did see the thread though as it starts some times when it is hot and not other times I did know if that was the same problem. Also would it explain it cutting out when slowing down and the drop in mpg.

I am going to say tired lift pump coupled with a tired FI pump.

Check that your new in tank pump is working, remove the relay and put an ammeter across the pins as described in another thread. Current draw should be about 4 amps or so. If it's much lower I would guess the pump is not working.

Check that your new in tank pump is working

Click to expand...

Must have missed the part about the new lift pump. Was it OE or Britpart ?

Britpart however the problem was there before the pump was replaced and she starts on empty now but needed 1/4 to 1/3 of a tank before or she would take an age to start.

is your car chipped? as this is common with chipped p38s. the cutting out bit..

Sorry but what is chipped?

dapper_dog said:

Britpart however the problem was there before the pump was replaced and she starts on empty now but needed 1/4 to 1/3 of a tank before or she would take an age to start.

Click to expand...

False economy methinks. Have you checked the main fusebox ? and I mean checked. That means having right out and inspecting ALL connections and relays for any signs of corrosion.

Pulled a few fuses and all looked fine no corrosion on them will look at the relays in the morning. No error messages showing up and nothing stored when computer plug in.

Pulled the relays and no corrosion on them. From what i can see with out stripping the fuse box down all looks good.
How strong should the fan run when the engine is hot as when the gauge is at 12:00 the fan is only spinning slowly? Could it be something to do with the temperature sensor as the water pump did explode when I was driving and the car cut out and was towed to a garage though the problem started before this.
Just remembered that when I got it it would to cut out when driving at a constant speed but once I got it serviced this problem stopped. They said my filter was full of water.

Symptoms now are as you change down especially when slowing to a stop and your foot is on the clutch the revs drop very fast and fall well below 700rmp idle speed causing it to cut out. This only happens when the engine is hot, either after 30 miles on open roads or if i drive a few miles from shop to shop doing messages. At this point the hot start problem kicks in but only if I dont restart it straight away like poping into a shop then it may take 20 - 30 turns to start and stay running. When it does start and you put your foot on the accelerator nothing happens for a few seconds then it revs as normal.
Don't know if this gives any more insight into my problem. But as I drive it for work I am stuck because I don't want to get stuck 60miles down country roads and no way to get home.

Had fues box out at weekend and all looks fine with it, no corrosion. I have been told that the fuel filter housing can give problems and suck in some air when hot could this be causing the problems outlined above.

Right, I had exactly the same problem, engine would cut out below about 2,000 revs, took to indie 4x4 garage who diagnosed and fixed the fuel lift pump as pointed out previously by various posters.

Have a look on rangerovers . net for short cut routes to replacing the lift pump.

Full procedure is to drop the tank and then lift the pump out, but by cutting through the floor you can leave the tank in place.

May be other problem with your relays/fuse box but it is more than likely to be this.

Your new pump is faulty would be my conclusion

Hi Adam,

The car is being taken away on Monday to have live data read when the problem occurs. The guy doing it rebuilt a P38 and reckons that the problem is with the thermostat as it wasn’t replaced when the water pump was. He said that RR recommend replacing the two along with the rad if you do anything to the cooling system though he will probably only replace the thermostat. Hopefully I will have an answer on Monday. Will keep you posted. Told him what you said about the pump but he is dubious but will check I out.

Peter

It looks like the viscous coupling in the fan has gone and is causing the engine to shut down to protect itself from over heating. New fan being installed and hopefully that will be the end of that.
Peter

That's a new one on me. Sounds like mechanic bull.

New fan going in this afternoon so I should know tomorrow. Hope he is right as it is a relatively cheep fix. Will let you know the outcome.

Peter

fuel injector gone needs reconditioning.